What it is

Minoxidil is one of two FDA-approved treatments for hair loss and has been approved for both men and women. Originally developed as an oral drug to treat high blood pressure, however, when patients started reporting unwanted hair regrowth after 3+ months of use, its manufacturers decided to reformulate it into a topical and begin testing it on men with androgenetic alopecia. Nowadays, minoxidil comes in both topical and oral forms, however, only the topical form is FDA-approved for hair loss.

Key Insights

• The in vitro evidence shows that minoxidil can affect hair growth in multiple ways: it is a vasodilator that increases blood flow to the scalp, as well as being a potassium channel opener which allows more oxygen, blood, and nutrients to reach the hair follicle.
• The clinical evidence shows that with topical methionine minoxidil, peak hair regrowth occurs in the first year, with growth slowly declining in subsequent years. However, continuous usage maintained the number of non-vellus hairs – meaning that with continuous use, past 1 year, it is likely that the number of new hairs grown will be maintained..
• Minoxidil must be used as a continuous support for hair follicles, otherwise hair regrowth ceases and hair loss will start again a few months after treatment is stopped. Some studies have also shown that the efficacy of minoxidil ranges from 20-40%, causing discontinuity of treatment in a large number of patients.
• The usual dosage of topical minoxidil is either 2% or 5% and oral dosages are commonly started at 0.625mg per day for women and 1.25mg for men.

Additional Links

• Minoxidil and its use in hair disorders: a review
• Five-year follow-up of men with androgenetic alopecia treated with topical minoxidi

What it is

Finasteride is one of two FDA-approved treatments for hair loss, and comes under a class of drugs called type 2 5α-reductase inhibitors. These drugs inhibit the enzyme type 2 5α-reductase which catalyzes the conversion of testosterone to dihydrotestosterone. The overactivity of this enzyme causes an increase in dihydrotestosterone which is associated with the emergence of androgenetic alopecia. Finasteride is probably the most well-studied hair loss treatment, and comes in both oral and topical forms, although only the oral form is FDA-approved.

Key Insights

• The in vitro evidence shows that finasteride is an effective 5α-reductase inhibitor which is beneficial for people with male pattern baldness.
• The in vivo evidence shows that oral finasteride administered at 0.5 or 2 mg/day alone or in combination with topical minoxidil can produce a similar reduction in serum dihydrotestosterone (DHT) in adult male stump tail macaques.
• 1mg/day of oral finasteride has been found to be an effective dose in male pattern hair loss, with men showing a 68.4% reduction in serum DHT levels after one year. Furthermore, treating men with androgenetic alopecia with 0.2 – 5 mg/day of finasteride for 4-6 weeks can reduce DHT levels by up to 65% in the scalp.
• Some people may experience sexual side effects from taking finasteride, so it is important to consult your doctor to potentially change the dose if you start to experience these.
• Finasteride is an easy-to-use product with high rates of success, and as such, may be a good choice for some hair loss sufferers.

Additional Links

• Finasteride: A Review of its Use in Male Pattern Hair Loss
• A systematic review of topical finasteride in the treatment of androgenetic alopecia in men and women

What it is

Dutasteride is a compound that is a selective inhibitor of both the type 1 and type 2 forms of 5α-reductase and is used to treat benign prostatic hyperplasia (BPH) in men with an enlarged prostate. This drug is now prescribed off-label to men with pattern hair loss – especially for those looking to achieve hair regrowth beyond what is expected with finasteride.

Key Insights

• The in vitro evidence shows that dutasteride is a dual 5α-reductase inhibitor, meaning that it inhibits both type 1 and type 2 isoforms of 5α-reductase which can be beneficial for patients with androgenetic alopecia.
• The clinical evidence shows that dutasteride treatment can significantly reduce the progression of hair loss in men with male pattern hair loss and is generally well-tolerated, although some sexual side effects have been observed (such as erectile dysfunction, and decreased libido). Dutasteride appears to reduce systemic dihydrotestosterone (DHT) levels by 92-96% and scalp DHT by 50-60%
• Because dutasteride inhibits both isoforms of 5α-reductase, it is thought that it might be more effective at treating hair loss than other inhibitors such as finasteride. This has been shown in clinical studies in which participants were treated with either finasteride or dutasteride. Dutasteride treatment significantly increased total hair and decreased the number of thin hairs compared to finasteride treatment, however most of these studies were completed over 6 months, whereas finasteride can take two years to achieve its full effect. In another comparison of oral treatments – this time with dutasteride, minoxidil and finasteride – it was found that 0.5 mg/day of dutasteride was the most efficacious, followed by finasteride (5 mg/day), minoxidil (5 mg/day), finasteride 1 mg/day), and then minoxidil (0.25 mg/day).
• If you choose to use dutasteride, a dosage of 0.5 mg daily appears to be the best dose as it outperforms finasteride yet does not result in long-term suppression of dihydrotestosterone after stopping – which can happen at higher concentrations.

Additional Links

• Superiority of dutasteride over finasteride in hair regrowth and reversal of miniaturization in men with androgenetic alopecia: a randomized controlled open-label, evaluator-blinded study
• Efficacy, safety, and tolerability of dutasteride 0.5 mg once daily in male patients with male pattern hair loss: a randomized, double-blind, placebo controlled, phase III study

What it is

Spironolactone is known as a diuretic (water pill), that prevents the body from absorbing too much salt and keeps your potassium levels from getting too low. Typically used to treat high blood pressure and heart attacks, spironolactone is also available on prescription to treat hair loss in women.

Key Insights

• The in vivo (in rats) evidence shows that spironolactone is an androgen receptor antagonist. This means that it can bind to proteins called androgen receptors, inhibiting the ability of hormones like testosterone and dihydrotestosterone to exert their effects.
• The clinical evidence suggests that spironolactone may increase hair density and decrease hair shedding. However, some patients experienced adverse effects such as hypertension, dizziness, nausea, and hyperkalemia (high potassium). Other clinical studies have found that a combination treatment of spironolactone and minoxidil led to an initial increase in hair shedding (for the first 3-6 weeks) followed by an overall reduction in hair shedding after 3 months and an increase in hair density at 6 months.

Additional Links

• Treatment of female pattern hair loss with oral antiandrogens
• Female pattern hair loss: a pilot study investigating combination therapy with low-dose oral minoxidil and spironolactone

What it is

Ketoconazole is an antifungal medicine used to treat skin infections caused by a fungus (usually yeast). You can buy 1% ketoconazole over the counter, but 2% ketoconazole usually requires a doctor’s prescription. Although not FDA-approved, ketoconazole is generally thought of as one of the “big three” treatments for pattern hair loss alongside minoxidil and finasteride.

Key Insights

• The in vitro evidence suggests that ketoconazole has anti-fungal, anti-androgenic, and anti-inflammatory properties which may benefit those with either telogen effluvium or androgenetic alopecia.
• The in vivo (in mice) evidence suggests that 2% ketoconazole topically applied once daily for three weeks significantly stimulated hair growth compared to the vehicle control.
• The clinical evidence suggests that ketoconazole has anti-inflammatory properties which may be beneficial for hair follicle growth. Furthermore, ketoconazole has been found to enhance hair thickness and proportion of anagen follicles at a similar rate to minoxidil in patients with androgenetic alopecia. Furthermore, ketoconazole was able to improve hair density nearly twice as well as minoxidil.
• The best candidates for ketoconazole shampoo are hair loss sufferers who are comfortable using the shampoo 2-3 times per week and who are dealing with dandruff and/or excessive hair shedding from androgenetic alopecia or telogen effluvium.

Additional Links

• Ketoconazole shampoo: effect of long-term use in androgenic alopecia
• Topical application of ketoconazole stimulates hair growth in C3H/HeN mice

What it is

Melatonin is a hormone produced by the brain that supports our circadian rhythm and helps us to sleep deeply. Melatonin also scavenges free radicals that can cause damage to our cells and/or accelerate the aging process. Over the years, various studies have been published to determine whether topical melatonin might help to fight hair loss.

Key Insights

• Low doses (0.1mg) of topical melatonin does not affect serum melatonin levels or internal production of melatonin by the body.
• The in vitro evidence suggests that areas of the skin and dermal papilla cells have receptor sites for melatonin indicating a potential for therapeutic use. Further research has shown that melatonin has an anti-androgenic effect on prostate cells indicating that it may behave similarly to drugs like finasteride – however there is no data in humans to confirm that this is how melatonin works. Additionally, melatonin has been found to behave like an antioxidant, which may help to reduce inflammation associated with hair loss – however, there is also no data in humans to confirm this. More recently, in vitro studies have found that melatonin can enhance the growth of 3D dermal papilla cultures, through the β-catenin pathway which is essential for the regulation of hair follicle cycling.
• The in vivo (in mice) evidence showed that hair follicles were both a source of melatonin and a target for melatonin-dependent signaling, as melatonin receptors were found to be expressed differentially depending on the stage of hair follicle cycle.
• The clinical evidence so far (6 studies) suggests that 0.1-1 mg topical melatonin is relatively safe and may decrease rates of “active hair loss”, for patients with early androgenetic alopecia, as well as improve hair counts, and increase hair density. The 1mg dosage however may affect serum levels of melatonin and has the potential to cause drowsiness. Furthermore, topical melatonin has been found to reduce the presence of seborrheic dermatitis and excessive sebum production. It’s important to note that some of these studies had low sample sizes, or no placebo, so further studies should be completed to address these issues.
• Topical melatonin may be a safe and effective treatment for those with early androgenetic alopecia.

Additional Links

• Melatonin increases anagen hair rate in women with androgenetic alopecia or diffuse alopecia: results of a pilot randomized controlled trial.
• Topical melatonin for treatment of androgenetic alopecia

What it is

Caffeine is a stimulant derived from plants, namely coffee and tea, and is arguably the most popular stimulant on the planet. Caffeine has been studied for its effects on the cardiovascular system, longevity, and hormones – some of which have also been studied in the context of hair loss treatments.

Key Insights

• The in vitro and ex vivo evidence suggests that topical caffeine can increase the growth of human dermal papilla cells through upregulation of ATP. Furthermore, caffeine was able to enhance hair follicle elongation in a comparable manner to minoxidil after 5 days of treatment. Additionally, caffeine treatment was found to reduce corticotropin-induced stress in hair follicles isolated from males with androgenetic alopecia, indicating a potential for counteracting stress-induced hair loss.
• There have been a number of clinical studies determining the effect of caffeine on hair growth. The vast majority of these studies reported a decrease in hair loss after using topical caffeine shampoo, as well as a decrease in hair loss when using caffeine in combination with minoxidil. Furthermore, patient satisfaction was reported to be higher when caffeine was used in conjunction with minoxidil.
• Oral caffeine consumption may instead have an adverse effect on hair growth through increased cortisol release, increased hyperglycemia in peripheral tissues, and potentially decreased thyroid activity.
• There have been no studies to determine if hair regrowth is sustained over time, however it’s thought, like most topicals, that its hair promoting effects will lessen over time. If you decide to implement caffeine into your regrowth regimen, it is probably better to avoid oral caffeine altogether – especially if you have a history of insulin resistance or hypothyroidism.
• From the current body of evidence, 0.2% topical and 1% caffeine shampoo concentrations appear to be the best choices.

Additional Links

• Caffeine and Its Pharmacological Benefits in the Management of Androgenetic Alopecia: A Review
• An open-label randomized multi center study accessing the non inferiority of a caffeine-based topic liquid 0.2% versus minoxidil 5% solution in male androgenetic alopecia
• Caffeine For Hair Loss (AGA): Evidence & Recommendations

What it is

Saw palmetto also known as Sabal fructus comes from the Serenoa repens fruit. Referred to as nature’s finasteride by some, studies have shown that saw palmetto extract may reduce levels of dihydrotestosterone (DHT) via the inhibition of 5α-reductase.

Key Insights

• The in vitro data for saw palmetto extract shows that it can inhibit 5α-reductase, which is causally related to hair loss through its dysregulation leading to an imbalance in the dihydrotestosterone/testosterone (DHT/T) ratio. Furthermore, it has been found to increase cell viability in keratinocyte cells treated with DHT and then saw palmetto extract compared to DHT-treated cells alone
• An in vivo study in mice (over 5 weeks) showed that saw palmetto rescued mice from DHT-induced loss of hair, however, it did not perform as well as finasteride. Furthermore, the mice treated with nothing grew hair back faster than either of the treated groups, indicating that some of the regrowth may be due to a natural entrance into anagen.
• The clinical data for saw palmetto shows that 38% of patients taking 320mg for two years reported hair regrowth, whereas after taking 1mg of finasteride daily for two years 68% reported hair regrowth. Furthermore, researchers reported that saw palmetto regrowth was only seen in the crown, and they did not show any before-and-after photos so the results cannot be seen for ourselves. Other studies that include saw palmetto also include many other ingredients that make it difficult to tell if the product is working due to saw palmetto or due to the other ingredients.
• Patients did report fewer side effects after taking saw palmetto extract than finasteride, however, this comes with the caveat of less effectiveness of treatment.

Additional Links

• Comparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study.
• Serenoa repens extracts promote hair regeneration and repair of hair loss mouse models by activating TGF-β and mitochondrial signaling pathways.
• Saw Palmetto: A Hair Growth Miracle? Mixed Evidence, Mixed Results

This section is a work in progress.

This section is a work in progress.

What it is

Rosemary oil is derived from the rosemary plant and is often used in perfumes, skincare, and hair care. Rosemary oil has antioxidant, anti-inflammatory, and antimicrobial properties that may benefit its use in cosmetics. More recently, studies have been looking at whether rosemary oil can be used as a treatment for pattern hair loss.

Key Insights

• The in vitro evidence suggests that rosemary oil contains anti-microbial, anti-inflammatory, and vasodilatory properties that may protect against aspects of hair loss; however, these studies did not look at cells or tissue relating to the hair follicle. Furthermore, rosemary leaf extract has been shown to inhibit 5α-reductase activity.
• The in vivo evidence (in rats and mice) suggests topical rosemary oil or leaf extract may improve hair growth at comparable levels to topical 2% minoxidil. However, the data collection measures for these studies may reduce the reliability of this data as they relied on subjective or non-standardized methods of measuring hair regrowth.
• Clinical studies in humans also show that topical rosemary oil treatment for 6 months was able to increase hair count at a comparable level to 2% minoxidil treatment; however, these increases were not that great compared to the baseline hair counts (mean 122.8 hairs at baseline compared to mean 129.6 hairs at 6 months for rosemary oil treatment).

Additional Links

• Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial
• Promotion of Hair Growth by Rosmarinus officinalis Leaf Extract
• Rosemary Oil For Hair Loss? Not So Fast… (See Photos)

What it is

L-carnitine is a chemical produced in the brain, liver and kidneys that helps the body turn fat into energy. Widely available as a supplement, L-carnitine is used by competitive athletes and has also been added to hair loss supplements.

Key Insights

• The in vitro/ex vivo evidence suggests that l-carnitine treatment can elongate hair follicles, prolong the growing stage (anagen), and reduce the levels of proteins that can induce the transitional (catagen) stage of the hair follicle cycle. This evidence, however, hasn’t been replicated.
• The clinical evidence suggests that topical L-carnitine application – over 6 months with twice daily application – can lead to an increase in the total number of hairs, the number of growing (anagen) hairs, and a decrease in the number of resting (telogen) hairs. These are noteworthy results. However, they have not yet been replicated. Further clinical studies are required to confirm these results.
• L-carnitine may improve hair growth outcomes. However, further studies are needed.

Additional Links

• Indications that typical L-carnitine-L-tartrate promotes human hair growth in vivo
• L-carnitine-L-tartrate promotes human hair growth in vitro

What it is

Adenosine is an important biomolecule that is present throughout the human body and is essential for the proper functioning of cells. Adenosine is a component and precursor of RNA and DNA and also acts as a neurotransmitter. Commonly used as a treatment for cardiac arrhythmia, adenosine has properties that slow down the heartbeat and dilate blood vessels.

Key Insights

• The in vitro and in vivo (in mice) evidence suggests that adenosine can increase the expression (gene and protein) level of key growth factors involved in hair follicle growth as well as increase the amount of time that hair follicles spent in the growing phase (anagen). Further studies in human dermal papilla cells (DPCs) showed that adenosine treatment enhanced gene and protein expression of key signaling pathways involved in hair follicle cycling (such as the Wnt/β-catenin pathway).
• The ex vivo evidence on human hair follicles showed that treatment with adenosine increased hair follicle growth prolonged the growing phase, and inhibited entry into the transitional stage of the hair cycle (catagen).
• The clinical evidence suggested that while adenosine treatment is not likely to improve hair loss outcomes, it may improve hair thickness over a long period of time (such as 12 months).
• One small study showed that combination treatment with topical caffeine led to increased hair density and reduced hair shedding; however, it’s impossible to know if the positive effects were due to the caffeine or the adenosine.

Additional Links

• Adenosine increases anagen hair growth and thick hairs in Japanese women with female pattern hair loss: A pilot, double-blind, randomized, placebo-controlled trial
• Topical adenosine increases the proportion of thick hair in Caucasian men with androgenetic alopecia

This section is a work in progress.

This section is a work in progress.

What it is

L-cysteine is a sulfur-containing amino acid found in protein-rich foods and produced by the body. It is a key component in the synthesis of keratin, a protein vital for hair structure.

Key Insights

• The in vitro evidence suggests that the amount of cysteine present in the hair fiber is an indicator of hair health.
• The in vivo (in animal) evidence suggests that L-cysteine and Vitamin B6 (which assist in L-cysteine incorporation) can inhibit the onset of alopecia in mice exposed to environmental cigarette smoke.
• There do not appear to be any clinical studies associating L-cysteine with hair follicle growth.

This section is a work in progress.

What it is

Retinoic acid – or all-trans-retinoic acid or tretinoin - is a metabolite of vitamin A that the body needs in small amounts to function and stay healthy.

Key Insights

• The in vitro evidence suggests that retinoic acid can increase levels of sulfotransferase which may increase minoxidil efficacy (as minoxidil exerts its effect through its activation by sulfotransferase).
• The ex vivo (in isolated cultured human hair follicles) evidence suggests that retinoic acid significantly inhibits hair follicle growth as well as induces the premature exit out of the growing stage (anagen) into the transitional stage (catagen) of the hair follicle cycle. Furthermore, an increase in a protein known to induce catagen, TGF-beta 2 was observed. In hair follicles isolated from patients treated with topical retinoic acid for 5 days, it was found that whilst sulfotransferase enzyme levels did not increase by any notable amount, the activity did significantly increase, which may subsequently increase the effectiveness of minoxidil.
• The in vivo evidence suggests that the combination treatment of retinoic acid and minoxidil, while significantly enhancing hair growth, was not as effective as minoxidil alone, suggesting that retinoic acid may not actually increase minoxidil efficacy – like previously thought with in vitro studies.
• Clinical research has typically determined the effect of retinoic acid in combination with minoxidil rather than alone. Some studies have found that while combination treatment with minoxidil does improve hair growth in patients with androgenetic alopecia, the effects have not been more beneficial than minoxidil alone.

Additional Links

• Towards dissecting the pathogenesis of retinoid-induced hair loss: all-trans retinoic acid induces premature hair follicle regression (catagen) by upregulation of transforming growth factor-beta2 in the dermal papilla.
• Efficacy of 5% minoxidil versus combined 5% minoxidil and 0.01% tretinoin for male pattern hair loss: a randomized, double-blind, comparative clinical trial

What it is

Peppermint is a hybrid species of mint that grows throughout Europe and North America. Peppermint oil is made from the flowers and leaves of the peppermint plant. For thousands of years, peppermint oil has been purported to assist with digestive disorders. Peppermint oil contains a large amount of menthol, which is responsible for the cool taste and refreshing smell, as well as some of its touted health benefits. Some claim that peppermint oil can be beneficial to hair health and growth through the potential vasodilatory properties of menthol.

Key Insights

• Peppermint has previously been found to have antibacterial properties which may benefit scalp health and therefore hair growth, however this has not been confirmed in humans.
• Menthol has also been found to induce vasodilation (widening of blood vessels) through multiple pathways. This may be beneficial to hair growth via increasing blood flow to the scalp.
• The in vivo (in mice) evidence shows one study that compared the efficacy of topical jojoba oil, 3% minoxidil, 3% peppermint essential oil, or a saline control applied once daily, 6 days a week for 4 weeks. The 3% peppermint group appeared to perform the best, (increased follicle number, follicle depth and dermal thickness) however this has not been reproduced in humans.
  Furthermore, there were three main issues with the study: (1) It was an animal study, (2) the study was conducted on a small sample of mice (20), and (3) the study only took place over four weeks.
• It is known that menthol (a component of peppermint oil) targets a number of pathways leading to vasodilation (widening of the blood vessels) which may contribute to improved blood flow, however it is also linked to vasoconstriction (constriction of blood vessels)

Additional Links

• Peppermint Oil Promotes Hair Growth Without Toxic Signs
• Evaluation of essential oil obtained from Methax piperita L. against multidrug-resistance strains
• Peppermint Oil for Hair Growth: Better Than Minoxidil?

What it is

Biotin, also known as vitamin B7 (or vitamin H), is part of the B-complex family of vitamins. Biotin plays a key role in hundreds of bodily functions and is considered essential to human health. We acquire biotin through our gut bacteria and through our food.

Key Insights

• The ex vivo (in the hair follicle) evidence suggests that certain levels of biotin are required for the maintenance of hair follicles and the production of keratin-producing cells.
• Many clinical studies that show a beneficial effect of biotin on hair follicle growth, are completed in patients with an underlying disease or genetic mutation that prevented them from absorbing dietary biotin. Furthermore, these studies were all completed in children.
• One study shows that biotin supplementation may provide a low efficacy for the treatment of hair loss after bariatric surgery that removes 75 – 80% of the stomach (called sleeve gastrectomy). However, the only measurement of efficacy was by patient-reported outcomes and not via quantitative means like a phototrichogram.
• Biotin supplementation may be useful for women dealing with hair loss who also have a biotin deficiency. However, this hasn’t been confirmed in clinical studies.

Additional Links

• A review of the use of biotin for hair loss
• Hair Loss After Sleeve Gastrectomy and Effect of Biotin Supplements
• Biotin For Hair Loss: Why This Supplement Is Overhyped & Oversold

What it is

Keratin is a protein that is a key structural component of hair, skin, and nails, providing them with strength and resilience. In hair loss treatments, keratin-based products are used to replenish and strengthen hair fibers, reduce breakage, and improve hair texture and appearance.

Key Insights

• In vitro and in vivo evidence suggests that intradermal injection of keratin can promote hair growth in mice due to the extracellular interaction of keratin with hair-forming cells.
• When applied to damaged hair, K31, a type of human hair keratin, can increase hair diameter by up to 49% and improve the mechanical strength of bleached hair by almost 2-fold.
• There is no clinical evidence showing that keratin can improve hair loss outcomes in humans.

Additional Links

• Keratin-mediated hair growth and its underlying biological mechanism
• Health improvement of human hair and their reshaping using recombinant keratin K31

What it is

Hydrolyzed wheat protein derived through a chemical process called hydrolysis. This is rich in proteins and amino acids, which are essential for a healthy metabolism. Hydrolyzed wheat proteins are widely used as ingredients in food and cosmetics because of these properties as well as functioning as an emulsifier (a stabilizer for emulsions). Many websites claim that hydrolyzed wheat protein is good for the hair, and as such it is used in some hair loss products.

Key Insights

• There is some data to show that treatment can penetrate the hair cuticle and improve damaged hair when applied to hair samples
• There is no clinical evidence to suggest that hydrolyzed wheat protein can improve hair loss outcomes. However, one study of 74 female subjects between the age of 18 – 50 with dry damaged hair used a shampoo and conditioner combination containing hydrolyzed wheat protein once daily. The researchers found that assessments from trained evaluators showed significant improvements in visual breakage, softness, and shine after three uses of the shampoo and conditioner.

Additional Links

• Modification of wheat gluten for improvement of binding capacity with keratin in hair
• Restoring dry, damaged hair with a novel natural wheat protein and wheat germ oil – containing shampoo and conditioner line

What it is

Green tea extract is an ingredient found in many natural topicals and supplements. Marketers claim that one of green tea's polyphenols – epigallocatechin gallate (EGCG) – helps to lower levels of dihydrotestosterone (DHT), and thereby improve androgenic hair loss.

Key Insights

• Cell culture studies suggest that green tea extract might lower DHT levels in hair follicle sites. However, there is no clinical data to see if these effects also occur in vivo, or if green tea by itself can improve hair loss outcomes.
• Green tea extract has been evaluated in some hair loss clinical studies – albeit alongside many other ingredients in a topical or supplement. This makes it impossible to discern the hair growth-promoting effects of green tea versus any other ingredient.

Additional Links

• An Uncontrolled Case Series Using a Botanically Derived, β-Cyclodextrin Inclusion Complex in Two Androgenetic Alopecia-Affected Male Subjects (Study)
• Human hair growth enhancement in vitro by green tea epigallocatechin-3-gallate (EGCG) (Study)

What it is

Vitamin B3 is an essential vitamin needed by the body to stay healthy and is found in many different plants, meats, and supplements. There are multiple forms of vitamin B3, including niacin and niacinamide. Niacinamide is used as an ingredient in hair loss treatments due to claims that it supports hair follicle growth.

Key Insights

• The in vitro/ex vivo evidence suggests that niacinamide may enhance hair growth by preventing oxidative stress-induced cell senescence and premature entry into the catagen stage of the hair follicle cycle. However, other in vitro studies claim that niacinamide does not stimulate hair follicle growth based on the fact that niacinamide has not been shown to induce vascular endothelial growth factor (VEGF) levels, which is a key growth factor involved in growth around the body and the hair follicle.
• The clinical evidence shows that although niacinamide-treated hair follicles have the potential to increase hair thickness, there is no evidence to show that it increases hair follicle growth.
• Topical niacin derivatives were suggested to improve hair fullness in female pattern hair loss. However, this outcome wasn’t measured using quantifiable means.

Additional Links

• Topical niacinamide does not stimulate hair growth based on the existing body of evidence
• A pilot study evaluating the efficacy of topically applied niacin derivatives for treatment of female pattern alopecia

What it is

Horsetail is a perennial herb in the Equisetaceae family of plants that have been used as a traditional medicine for bladder and kidney conditions as well as to promote wound healing. Horsetail has a high silica content and contains selenium and cysteine which have been touted to promote healthier hair.

Key Insights

• The in vitro evidence suggests that horsetail extracts may reduce levels of reactive oxygen species, which can negatively affect hair growth, however, this has not been completed in hair follicles or shown in humans. Furthermore, horsetail extracts have been found to inhibit 5α-reductase and reduce levels of the inflammatory marker interleukin-6 (IL-6), which indicates a potential beneficial effect on hair growth.
• There is little to no evidence to suggest that silica is beneficial to hair growth, however in rats it is concentrated in the hair and skin. This suggests that silica deficiency may result in negative effects on the structure of hair shafts.
• The clinical evidence suggests that selenium (an element found in horsetail) can prevent hair loss in patients undergoing chemotherapy for ovarian cancer, however, selenium was included amongst other vitamins and minerals so it cannot be stated for certain that selenium was the protective element.

Additional Links

• Selenium as an element in the treatment of ovarian cancer in women receiving chemotherapy
• Inhibition of 5α-Reductase, IL-6 Secretion, and Oxidation Process of Equisetum debile Roxb. ex Vaucher Extract as Functional Food and Nutraceuticals Ingredients

This section is a work in progress.

What it is

Panthenol is a chemical substance made from pantothenic acid. This is known as a humectant, which means that it holds and binds water, which means that it is often used in moisturizers to lock in water.

Key Insights

• The in vitro evidence suggests that panthenol treatment can enhance the proliferation of dermal papilla cells (specialized cells involved in hair follicle growth and cycling). Furthermore, panthenol has been found to reduce the expression of TGF-β1, a known factor involved in the induction of catagen (the transitional stage between growing and non-growing).
• The ex vivo evidence suggests that panthenol may stimulate hair follicle growth when treated with either 20 or 40 µg/ml. However, this was completed in mink hair follicles and not in humans.
• One clinical study was conducted in 21 women with female pattern hair loss. The participants received 500 mg of intramuscular dexpanthenol weekly for 8 weeks. Overall satisfaction with the appearance of hair was 57.1% “I am satisfied”, 28.6% “I am very satisfied”, and 14.3%, “I am neutral”.
• The only other clinical evidence we could find for panthenol was with usage in combination with a number of other ingredients, so it is not possible to know if the effects are due to panthenol alone.

Additional Links

• Pantothenic acid promotes dermal papilla cell proliferation in hair follicles of American minks via inhibitor of DNA binding 3/Notch signaling pathway
• Dexpanthenol promotes cell growth by preventing cell senescence and apoptosis in cultured human hair follicle cells

This section is a work in progress.

What it is

Collagen is a protein produced by the body that plays an essential role in the structure and function of skin, cartilage, bones, and connective tissue. There are two types of collagen, type 1 and type 2. Type 1 collagen makes up 90% of the collagen found in the human body. Collagen is a widely available supplement that is claimed to stimulate hair growth, prevent loss and delay graying.

Key Insights

• The outermost layer of the hair follicle has been found to be a source of pro-collagen, the precursor to type 1 collagen, indicating a role in hair follicle structure and growth.
• The in vitro evidence suggests that collagen peptides -isolated from fish- enhance cell growth (proliferation) of human dermal papilla cells (specialized cells involved in hair follicle growth and cycling); however, it’s not known what effect enhanced proliferation of dermal papilla cells would have on the growth of the hair follicle.
• The in vivo (in animals) evidence suggests that topical collagen peptide treatment may enhance hair follicle growth in comparison to the control, and increase the number of growing (anagen) hair follicles compared to non-growing (telogen) follicles.

Additional Links

• Hair-Growth-Promoting Effects of the Fish Collagen Peptide in Human Dermal Papilla Cells and C57BL/6 Mice Modulating Wnt/β-catenin and BMP Signaling Pathways
• Connective tissue sheath of hair follicle is a major source of dermal type 1 procollagen in human scalp
• Collagen For Hair Loss: Untangling The Truth

This section is a work in progress.

What it is

Hyaluronic acid is known for its hydrating properties. It potentially improves scalp health and hair texture by retaining moisture, though there is no clinical evidence supporting its role in hair regrowth.

Key Insights

• The in vitro (in cells) data suggests that non-crosslinked hyaluronic acid filler can restore dermal papilla cell viability against UVB-induced cell death and also increase vascular endothelial growth factor secretion (a growth factor involved in hair follicle cycling).
• There does not appear to be any clinical data supporting the use of hyaluronic acid for hair regrowth.

Additional Links

• In Vitro Hair Growth Promoting Effect of a Non Crosslinked Hyaluronic Acid in Human Dermal Papilla Cells

What it is

Castor oil has been considered a folk remedy for ailment ranging from constipation to skin rashes for centuries. More recently, however, it has gained popularity amongst the hair loss community. Castor oil is rich in triglycerides including one called ricinoleic acid which may be beneficial to hair growth.

Key Insights

• The in vitro evidence suggests that castor oil has antimicrobial properties which may benefit patients with androgenetic alopecia.
• The in vivo (in rabbits) evidence suggests that topical castor oil can increase the length, softness, and thickness of hair in more than 50% of animals compared to the control. This however has not been proven in humans.
• There is no published research that clinically investigates how castor oil might improve hair growth.

Additional Links

• Antimicrobial action of sodium hypochlorite and castor oil solutions for denture cleaning – in vitro evaluation.
• Preclinical study on the hair growth and regeneration of external use lotions containing castor oil Ricini Oleum in rabbits

This section is a work in progress.

What it is

Aloe vera is a commonly used ingredient in cosmetic ingredients because of its antioxidant, anti-inflammatory and moisturizing properties.

Key Insights

• The in vitro evidence suggests that aloe vera enhances skin permeation, suggesting that it may assist in drug delivery.
• There is no clinical evidence to suggest that aloe vera enhances hair regrowth.

Additional Links

• Skin permeation enhancement potential of Aloe Vera and a proposed mechanism of action based upon size exclusion and pull effect

What it is

Acetyl-tetrapeptide-3 is a biomimetic peptide that has been derived from another peptide which stimulates tissue remodeling. Recently, it has been used as an ingredient in some topical treatments that claim to treat hair loss.

Key Insights

• The in vitro (in cells) evidence suggests that acetyl-tetrapeptide-3 may enhance the gene expression of collagen III and collagen VII – types of collagen that are present in the hair follicle which may help to maintain hair anchorage within the scalp.
• The ex vivo (in skin explants) evidence suggests that after corticosteroid treatment which diminished collagen VII expression, acetyl-tetrapeptide-3 treatment was able to return expression levels back to the control level.
• Unfortunately, the clinical studies that do include acetyl-tetrapeptide-3 do not measure the effects of it alone, but rather in combination with a number of other ingredients, so we can’t say for sure what effect it has on hair loss in humans.

Additional Links

• A new strategy to module alopecia using a combination of two specific and unique ingredients
• An Herbal Extract Combination (Biochanin A, Acetyl tetrapeptide-3, and Ginseng Extracts) versus 3% Minoxidil Solution for the Treatment of Androgenetic Alopecia: A 24-week, Prospective, Randomized, Triple-blind, Controlled Trial

What it is

Red clover is a wild flowering plant that belongs to the same family as peas and beans. Biochanin A is an isoflavone found in red clover that has anti-inflammatory, cancer preventive, and neuroprotective properties. Red clover has been used as an ingredient in hair loss supplements.

Key Insights

• The in vitro evidence suggests that biochanin A might inhibit 5α-reductase activity. 5α-reductase is responsible for catalyzing the conversion of testosterone to dihydrotestosterone (DHT) and increased activity (and subsequent increased DHT) is linked to the formation of androgenetic alopecia. Furthermore, red clover extract has been found to have anti-inflammatory properties which may be beneficial for those with hair loss disorders.
• The only clinical evidence we could find was a topical mixture of red clover extract in combination with another compound called acetyl-tetrapeptide-3 in participants with hair loss for 4 months. The topical mixture treatment led to a significant increase in the density of growing hairs and a reduction in non-growing hairs.

Additional Links

• Structure-activity relationships for inhibition of human 5α-reductases by polyphenols
• A new strategy to modulate alopecia using a combination of two specific and unique ingredients

What it is

Key Insights

• The ex vivo evidence suggests that propylene glycol can improve the penetration of drugs through the skin.
• Propylene glycol may cause allergic contact dermatitis in some people; however, this is an uncommon side effect. In a retrospective study of 6761 patients, 9 had a relevant positive reaction to propylene glycol.
• Because propylene glycol is a humectant (meaning that it locks in moisture), it may be more beneficial for those with dry scalps.

Additional Links

• Effect of propylene glycol on the skin penetration of drugs
• Allergic contact dermatitis from propylene glycol: A case series from Australia

What it is

Key Insights

• Glycerin is a carrier agent known for its ability to lock in skin moisture and is the third most frequently used cosmetic ingredient.
• Glycerin can help maintain or restore the epithelial barrier and can help break the “itch-scratch” cycle for those with itchiness.
• It has also been used as an anti-dandruff and anti-inflammatory ingredient.
• A safety assessment has found glycerin to be safe as a cosmetic ingredient.

Additional Links

• Itch Management: Topical Agents
• Glycerin is a carrier aSafety Assessment of Glycerin as Used in Cosmetics
• How safe are glycerin and polyglycerin-10 as key ingredients in personal care products

This section is a work in progress.