Caffeine consumption – usually in the form of a morning coffee or an afternoon cup of tea – is a staple of many people’s lives and, in some cases, the only way they get a much-needed boost for the day.
After all, this substance is known as a stimulant of the Central Nervous System (CNS) (1).
But, did you know that caffeine, when applied topically to the scalp, may actually stimulate hair growth?
Even further, these results have been seen explicitly in human hair follicles, which indicates its possible positive effect on the treatment of Androgenetic Alopecia (AGA) and similar hair loss patterns.
In this article, we’ll discuss the various scientific studies that have indicated caffeine as a possible hair-growth stimulant. We’ll also discuss what these results can mean for various types of hair loss, as well as a few alternative and complementary therapies to consider.
What Is Caffeine?
Caffeine is a bitter, crystalline compound that belongs to the methylxanthine class, a group of naturally-occurring alkaloids. This compound is known to stimulate the CNS and is found in foods (e.g. coffee, tea, cacao beans), cosmetics, and both prescription and over-the-counter medications (1).
How Is It Used?
Caffeine is most often consumed in the form of coffee or tea. It can be used as a short-term treatment of drowsiness and fatigue, as a diuretic, and in the treatment of headaches and migraines (2, 3, 4).
This stimulant is also increasingly being used in cosmetics, such as facial creams, shampoos, and hair masks. In some cases it’s even used to treat under-eye circles and wrinkles (5).
Is Caffeine a Viable Hair Loss Treatment?
Hair loss is a complicated condition with a variety of causes. The most common cause, though, is Androgenetic Alopecia (AGA) which is a hereditary condition that can affect both men and women (6).
The presentation in men and women is different, with men suffering from the common M-shaped pattern of loss and women typically losing hair at the crown. However, the major factor in AGA in both sexes is the same – a sensitivity to the androgen hormone Di-hydrotestosterone (DHT) (7).
This concern regarding side effects is where the use of naturally derived alternatives such as caffeine come in.
Caffeine has only recently been considered as a possible aid for reestablishing healthy hair. Its various mechanisms – including its effect on the proliferation and elongation of human hair follicles and its ability to penetrate the scalp deeply and increase cutaneous blood flow – make it a possible treatment option for hair loss and thinning.
However, it’s important to consider the scientific research that’s been carried out on this ingredient before making a decision.
Study: Effect of caffeine and testosterone on the proliferation of human hair follicles in vitro
When discussing the possibility of hair growth, one element to consider is how a substance – caffeine in this case – affects the hair follicle.
In 2007, German researchers put caffeine to the test by studying its effects on proliferation of human hair follicles in vitro (i.e. in a laboratory setting) (10).
The follicles in this study were taken from 14 biopsies obtained from the scalps of male AGA patients. They were cultivated for 120 to 192 hours with a control or in a medium containing different concentrations of testosterone and/or caffeine.
Hair shaft length and keratinocyte proliferation were measured throughout the course of the study.
The hair follicles exposed to only testosterone showed significant growth suppression, while those exposed to only caffeine were shown to significantly increase in length and number.
The follicles exposed to both testosterone and caffeine were shown to increase in length which indicates that caffeine counteracts testosterone’s effects.
In the end, researchers declared that:
“caffeine was identified as a stimulator of human hair growth in vitro; a fact which may have important clinical impact in the management of AGA.”
Study: Follicular penetration of topically applied caffeine via a shampoo formulation
As the previous study shows, caffeine stimulates hair follicle growth when directly in contact with the follicles. Direct contact is not common in human studies, though, as the caffeine must first penetrate the scalp.
Another study performed in 2007 looked to answer whether caffeine, when applied topically in the form of shampoo, would penetrate the scalp so as to benefit the follicles (11).
The caffeine shampoo was applied to the scalp and left on for two minutes before being washed away.
To determine the penetrative abilities, the researchers used a few different testing methods. The first was with the use of highly sensitive surface ionization, and the second was through mass spectroscopy which detects “very small quantities of transcutaneously absorbed substances in the blood.”
The results of the study indicate that caffeine penetrated the scalp via the hair follicle and the stratum corneum layer after two minutes of topical contact.
This means that caffeine applied topically to the scalp will be absorbed and can benefit the follicle in human subjects, just as it does in laboratory settings.
Study: Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and transforming growth factor-β2/insulin-like growth factor-1-mediated regulation of the hair cycle in male and female human hair follicles in vitro
To expand upon the findings in the first study outlined above, German researchers again returned to the laboratory to test the effects of caffeine on various key growth parameters using male and female hair follicles in vitro (12).
The goal of this study was to determine the exact mechanism by which caffeine benefits the follicle.
The collected follicles were partially dissected and treated in a culture containing testosterone alone, or a combination of testosterone and caffeine for 120 hours.
The effects of the test substances on the cultures were then examined using histomorphometry. The measured effects included:
- Hair follicle cycling (anagen-catagen transition)
- Hair matrix keratinocyte proliferation
- Expression of a key catagen inducer, transforming growth factor (TGF)-β2
- Expression of the anagen-prolonging insulin-like growth factor (IGF)-1
As indicated by the previous study, caffeine enhanced follicle elongation and stimulated hair matrix keratinocyte proliferation. This study also showed that caffeine prolonged anagen duration.
Interestingly, the female hair follicles were more sensitive to the caffeine than male follicles but in both sets caffeine enhanced the expression of IGF-1 protein.
The researchers concluded that the:
“study reveals new growth-promoting effects of caffeine on human hair follicles in subjects of both sexes at different levels (molecular, cellular and organ).”
Study: Effect of caffeine contained in a cup of coffee on microvascular function in healthy subjects
The effects of caffeine on blood flow and cardiovascular risk have long been debated. In 2015, a group of researchers in Japan decided to take one step towards putting this debate to rest (13).
The double-blind, placebo-controlled study included 27 healthy subjects ranging in age from 22 to 30. These participants did not regularly consume coffee.
On the first day of the study, the participants drank one five-ounce cup of either caffeinated or decaffeinated coffee. Finger blood flow was then measured using laser Doppler flowmetry.
Two days later, the participants were then given another five-ounce cup of the other type of coffee.
The researchers found that caffeinated coffee “slightly but significantly elevated blood pressure and decreased finger blood flow as compared with decaffeinated coffee intake.” It did this without increasing heart rate in either group.
But what exactly does this indicate?
As researchers concluded:
“These results provide the first evidence that caffeine contained in a cup of coffee enhances microvascular function in healthy individuals.”
This is great news for all coffee drinkers, but even more so for hair loss sufferers.
Healthy blood flow plays a critical role in the hair growth process, as a steady flow of blood is needed to deliver oxygen and vital nutrients to the follicles. The follicles then use these nutrients to produce keratinocytes which promote hair growth.
In short, a healthy cardiovascular system is the key to a healthy scalp.
Study: An open-label randomized multicenter study assessing the noninferiority of a caffeine-based topical liquid 0.2% versus minoxidil 5% solution in male androgenetic alopecia
Of particular interest to men and women with AGA may be the results of a study that compared the efficacy of caffeine to minoxidil 5 percent solution (14).
The study included 210 males aged between 18 and 55 years with AGA. The subjects were split evenly into two groups. The first group was to apply the caffeine-based topical liquid twice per day, and the second group was to apply the minoxidil 5 percent solution once per day.
Treatment continued for six months.
The primary goal of the study was to determine the percentage change in proportion of anagen hairs from baseline to six months which was determined using trichograms.
The group of the 0.2 percent caffeine solution had an anagen improvement of 10.59 percent, while the group of the 5 percent minoxidil solution had an anagen improvement of 11.68 percent.
This indicates that there is very little difference between the efficacy of caffeine solution and minoxidil in this particular study, and this may show caffeine’s possible use in the treatment of AGA in the future.
Limitations and Considerations
While the above results seem to indicate that caffeine can hold its own when it comes to treating AGA-induced hair loss, there are a few things to mention.
Foremost, the caffeine solution used in this study contained more ingredients than just caffeine. And some of these ingredients – including menthol and niacinamide – may have themselves contributed to the positive results seen.
Menthol has been shown to increase cutaneous blood flow, which is essential for hair growth (15). It has also been proven as an anti-inflammatory and may contribute to a healthy scalp environment (16).
Niacinamide, a form of vitamin B3, has been shown to increase the synthesis of keratin (17). It can also reduce water loss and improve moisturization, both of which can protect the hair from breakage and other damage.
With this in mind, it’s difficult to say just how much of the results seen above are from the caffeine and how much are from the other ingredients within the solution.
Further studies, those which focus caffeine alone, would be more helpful when comparing its efficacy to conventional treatment options such as minoxidil.
What Types of Hair Loss May Caffeine Help?
Caffeine has many proven scientific benefits, including hair shaft elongation and keratinocyte proliferation. These may be beneficial to the treatment of many hair loss conditions, but do keep in mind that the majority of studies on the topic are performed on animals or in vitro.
The most frequently-studied hair loss condition, AGA, has been examined in some of the studies above. This is because AGA has far-reaching effects on the hair follicle and suppresses growth in a number of different ways.
However, caffeine may be beneficial in stimulating hair growth for other causes of shedding and balding, too.
Alopecia Areata (AA) is an autoimmune condition in which your body mistakes the hair follicles for foreign invaders and attacks them with seemingly no trigger. This results in patchy, bald patches on the scalp.
Other causes of hairline recession and loss include illness, injury, medications, stress, poor lifestyle choices, and hormonal imbalance.
Caffeine is of course not the perfect solution. However, its use may stimulate hair growth in people with a variety of scalp conditions due to its far-reaching effects including the ability to stimulate blood flow and promote hair follicle cell differentiation and proliferation (12, 13).
Of course, further studies (particularly those on humans) must be undertaken to gain a better understanding of the possible positive implications.
Caffeine Dosage for Hair Growth: How Much Is Enough?
As with many substances, too much of a good thing can be bad. This is why it’s important to understand how much caffeine is too much.
Unfortunately, the answer to this question is still debated.
The study mentioned previously that compared a 0.2 percent caffeine-based topical with 5 percent minoxidil solution may provide some insight.
The hair regrowth results between the two groups were insignificant, which means the 0.2 percent caffeine-based topical is almost as effective as the minoxidil. The subjects in this caffeine group applied 2mL of the 0.2 percent solution twice daily which may be a good place to start.
General Warnings and Precautions
An important thing to note is that the adverse effects of topical caffeine have not been fully studied and, as such, there is no way to know whether caffeine-sensitive individuals will react to a topical solution.
The most common adverse effects associated with caffeine consumption include anxiety, insomnia, rapid heart rate, and fatigue (18). It’s also possible to become dependent on the stimulant when it is consumed regularly.
There are also certain populations which should avoid or limit consumption of caffeine and who should speak with their physicians before using a topical solution. These include (18):
- Children and adolescents
- Women who are pregnant or lactating
- People with underlying heart conditions
- People with mental illness
Ultimately, there is still much research to be done before the adverse effects of topical caffeine solutions are better understood.
Complementary and Alternative Treatment Options
You can consider an array of natural hair growth therapies as a complement to your use of caffeine or as an alternative.
Let’s look at a few of the more effective options.
If you want to naturally stimulate the follicles to allow for cell proliferation and elongation, you’ll want to consider adding one technique to your hair care routine – scalp massage. Massages are the manual manipulation of the scalp and its surrounding tissues to increase blood flow while also stretching the Dermal Papilla Cells (DPCs) (19).
This would be best done in conjunction with the use of a naturally-derived hair product, such as a caffeine shampoo.
You simply apply the shampoo to your scalp as you would with any other, and then use massage to deliver the product throughout your scalp and hair.
You can perform these techniques with your fingertips or with a specialized massaging tool.
The fingertips are the best way to target specific areas of the scalp especially when applying shampoo.
To begin, place your thumb, index, and middle fingers on the sides of your scalp. Move your fingers around the area using gentle, circular motions and then slowly move them up towards the crown.
Continue with the circular motions for one to two minutes in each area. After the crown, move to the hairline, return to the sides of the head, and then last to the base of the skull.
The massage should take ten minutes total, and it’s recommended that you perform a scalp massage at least once per day.
Scalp massages are simple enough, but did you know you can use basic facial movements to stimulate the scalp, too?
These movements are known as scalp exercises and they similarly increase blood flow while reducing tension and increasing skin elasticity.
The simplest technique involves the use of your eyebrow muscles. Here’s how.
- Lift your eyebrows as high as possible and hold them in place for one minute. Return them to neutral position. You can repeat this movement five to 10 times per session.
- Furrow your eyebrows as deep as possible and hold them in place for one minute. Return them to neutral position. You can repeat this movement five to 10 times per session.
For a more streamlined routine, you can alternate the movements by first lifting your eyebrows and then furrowing them deeply without stopping at the neutral position in between.
To save time and improve efficacy of this technique, you can use a caffeine-based topical solution while performing the exercises.
Massages and exercises are a great practice to include in your regular hair care routine, but there are more ‘advanced’ techniques you can use. Microneedling is one such technique.
Microneedling is a process wherein small needles are used to pierce the skin on the face, scalp, or elsewhere on the body. This practice creates small wounds which, as they heal, induces collagen production and stimulates cell proliferation (20, 21).
When performed correctly, microneedling does not cause scarring and will leave your skin in better condition than before (22).
You can perform microneedling with the use of a specialized tool, either a dermaroller or a dermastamp.
The dermastamp is the superior of the two as it enables you to target areas of hair loss more efficiently and reduces the risk of pulling healthy hairs from the root as can happen with the roller.
Whichever tool you choose, the procedure should be performed no more than once per week.
You’ll first want to cleanse the scalp with an exfoliant peel to enhance the results, and then go over each area of the scalp three to four times.
You can then apply a topical solution – such as one containing caffeine – to improve the outcome.
The importance of increasing blood flow to the scalp – and the fact that topical caffeine can help to do so – has been discussed. One way to further ensure this outcome, though, is via inversion therapy.
Just as it sounds, inversion therapy is the practice of inverting the body (i.e. hang it upside down) so as to drive blood flow towards the top of the body and, more specifically, the head. The inversion may be full – for example, with patients hanging vertically from the ankles – or partial – with the patient in a seated position, their hips flexed at 90 degrees and inverted at 60 degrees.
In fact, a full review on inversion therapy and its possible physiological effects was performed in 1985 (23).
With regards to cardiovascular effects, the researchers found that partial inversion was best for reducing the risk of cardiovascular risks (including increased blood pressure and pulse rate) which is often seen in full inversion procedure (23, 24).
However, further studies must be carried out to determine the true effects of full versus partial inversion.
So, how should you add inversion therapy to your hair care routine?
First, apply a caffeine topical.
Second, find a comfortable position and perform partial inversion for three minutes.
One simple method is to lie on a chair or couch and swing your legs over the back side. Your bottom should be pressed up against the back of the seat, and your face directed towards the ceiling.
Now, scoop back just enough to hang your head over the edge of the chair or couch. Do not put too much strain on the neck, but you do want to get as close to a 60 degree angle as possible.
You can perform this technique in three minute intervals for the length of time you’re wearing the topical. Just be sure to be wary of any side effects – including dizziness or lightheadedness – and reduce the time if necessary (24).
As many topical products recommend you leave the product on for an extended time, you can use inversion therapy to waste a bit of that time and increase the possible positive effects of the caffeine topical.
Caffeine is a powerful central nervous system stimulant, but numerous studies have also implicated this compound as a possible stimulator of hair growth. It’s been shown to lead to the proliferation of DPCs and the induction of anagen phase – both in vitro and in vivo (10, 12).
That’s not to say that caffeine is the perfect answer for your hair loss woes. But instead, it could be a beneficial addition to your current hair care routine.
And whether you want to apply it as a shampoo, conditioner, or hair mask, caffeine has also been shown to absorb successfully into the scalp (11). This means that almost any application technique you use could have a positive affect in the fight against hair loss.
So whether you want to use it as a standalone treatment, or alongside various other proven therapies, caffeine may prove to be an important part of your hair growth journey.