Adenosine is not a name you often come across when reading about hair loss. Minoxidil, finasteride, and Redensyl are known to almost everyone who has done even a little bit of searching. Adenosine is not. Yet, it has been used in hair lotions and shampoos in Japan and Korea for years, and there is more independent research on it than on many ingredients that are well known.
That research, however, is not as unambiguous as some webshops would have you believe. In this blog, you will read what adenosine is, what it does in your hair follicle, what the studies really show, and where its effectiveness ends. We will also address the question often seen on Reddit: does caffeine cancel out the effect of adenosine?
What is adenosine?
Adenosine is a substance that your body produces itself. It is present in every cell, including as part of ATP, the molecule that cells use as fuel. In addition, it acts as a signaling molecule: it attaches to special receptors on cells and triggers a response. In your brain, for example, adenosine ensures that you feel tired at the end of the day.
Adenosine has long been used in cosmetics, especially in creams for wrinkles. For hair, it came into the picture when Japanese researchers discovered its effect on the cells at the base of the hair follicle.
What does adenosine do in your hair follicle?
At the base of every hair follicle is the dermal papilla. This is a small group of cells that tells the hair follicle when to grow and when to rest. These cells have receptors for adenosine, particularly a type called A2B.
When adenosine binds to these receptors, the cells begin to produce more growth factors. The most important one is FGF7, a signaling molecule that keeps the hair follicle in the growth phase. In lab studies with cultured scalp cells, the production of FGF7 increased by up to about double.
What is not accurate is that adenosine blocks DHT like finasteride does. It does not intervene with the hormone that drives hereditary hair loss. It works a step later: it tries to support the growth phase of hair follicles that are slowly shrinking due to DHT. You can read about how that shrinking process works in DHT and hair loss.
An interesting detail: a 2001 lab study indicated that minoxidil in the dermal papilla works partly because the cells themselves start releasing more adenosine. The two agents are part of the same story, just via a different entry point.
What do human studies show?
There are seven clinical studies involving adenosine on the scalp. The best known:
- Japanese women, 2008: 30 women, 12 months, a lotion with 0.75% adenosine versus placebo. More hairs in the growth phase and more thick hairs in the adenosine group.
- Japanese men, 2015: 102 men, 6 months, adenosine versus a lotion with niacinamide. More thick hairs with adenosine.
- European men, 2016: 38 white men with hereditary hair loss, 6 months, versus placebo. The proportion of thick hairs increased and the proportion of thin, wispy hairs decreased.
- Iran, 2013: 110 men, 6 months, 0.75% adenosine versus 5% minoxidil. Adenosine performed as well as minoxidil, and the men were more satisfied with it, as they felt it worked faster.
That sounds good. But there are a few caveats you should be aware of.
Most studies are small. A large portion was conducted by researchers from Shiseido, a Japanese company that sells its own adenosine products. And in the Iranian study, recovery in both groups was low. Therefore, "no worse than minoxidil" mainly means that neither product showed much results in that study.
The 2025 review study: less rosy
In 2025, Polish researchers compiled all the studies in the journal Biomolecules. Their conclusion is worth reading because it is much more cautious than the individual studies.
- All seven studies reported less hair loss and higher hair density.
- They described the quality of the evidence as very low to moderate.
- Three studies were similar enough to be combined. After 6 months with 0.75% adenosine, there was a trend toward more thick hairs and fewer thin hairs, but the difference compared to placebo was not statistically significant.
The researchers still found adenosine worth trying, especially for people who cannot or do not want to use minoxidil or finasteride. That seems like a reasonable summary to us: safe, the direction is correct, but it is not an agent that is hard-proven to reverse your hairline.
Does caffeine cancel out the effect of adenosine?
This question keeps coming up on forums, and it is a valid one. Caffeine blocks adenosine receptors. That is how coffee keeps you awake: it sits on the spot where adenosine normally sends its tiredness signal. Wouldn't caffeine on your scalp do the same thing to adenosine?
Short answer: no one knows for sure. There is no study that has tested them side by side. However, here are a few things to consider:
- Caffeine likely works in the hair follicle primarily in a different way, by inhibiting an enzyme that breaks down cAMP. Adenosine increases cAMP via the A2B receptor. In that respect, they push in the same direction.
- Whether caffeine in the amount present in a serum occupies enough A2B receptors in the dermal papilla to hinder adenosine has never been measured.
- A shampoo with 0.4% caffeine and 0.2% adenosine was tested. The participants were satisfied, but there was no control group, so you cannot derive anything definitive from it.
We are open about this because our own Growth Serum contains both substances. Based on what is known, we do not expect them to cancel each other out. But it is not proven, and that is something you should know. You can read more about caffeine itself in caffeine against hair loss.
Adenosine or minoxidil?
If you compare purely on evidence, minoxidil wins. It is an approved drug with decades of large studies. Adenosine has a handful of small studies.
On the other hand, adenosine causes few problems. Almost no side effects occurred in the studies. In the comparison with minoxidil, 3.8% of the adenosine group complained of something, compared to 9.8% with minoxidil. You do not need a prescription for it, and as far as is known, it does not cause a shedding phase at the beginning.
For whom is adenosine interesting?
- Men with early-stage hair loss who do not (yet) want to use medication.
- Men who cannot tolerate minoxidil, for example due to an irritated scalp.
- As a supplement to an existing approach, because it works via a different route.
For whom is it less suitable? For those who have had bald patches for years. Adenosine can support a hair follicle that is still alive. It will not bring back a hair follicle that has long since ceased producing hair. See also when is hair loss still reversible. If you are doubting between a serum and medication, serum or medication for early-stage hair loss will help you further.
What should you look for when buying a product with adenosine?
In the studies, it almost always involved a lotion with 0.75% adenosine that remained on the scalp. You wash away a shampoo after a minute, so you should expect less from it.
The concentration is almost never stated on the packaging. You can check the ingredient list to see where adenosine is listed: the further back it is, the less it contains. A product that relies almost entirely on adenosine should be viewed with the same level-headedness as the studies themselves.
In the Hairborn Growth Serum, adenosine is one of twelve ingredients, along with Redensyl, Procapil, Capixyl, AnaGain, and caffeine, among others. The idea is that they each tackle a different part of the process. Adenosine is a supporting player for the growth phase, not the lead actor. Some men use a derma roller once a week to improve absorption. How to do that safely is explained in combining a derma roller and serum.
Whatever product you choose, give it time. In all studies, measurements were only taken after six months, and for good reason. Why it takes so long is explained in how long does it take for a hair serum to work.
In short
Adenosine is a naturally occurring substance that supports the hair follicle's growth phase in lab studies. Human studies point in the same direction but are small and often funded by a company with a vested interest. When combined, the effect is not statistically hard. It is safe, well-tolerated, and makes sense as part of a broader approach. As a standalone solution for hereditary hair loss, we would not count on it.
Frequently asked questions
What exactly is adenosine?
Adenosine is a substance that your body produces itself and which is found in all your cells. It is, among other things, a building block of ATP, the energy source for cells, and it acts as a signaling molecule via special receptors. It has long been used in cosmetics to combat wrinkles. It is interesting for hair because the cells at the bottom of the hair follicle have receptors to which adenosine can bind.
Does adenosine really work against hair loss?
Adenosine shows a modest effect in small studies, but it is not hard-proven. Seven clinical studies reported more thick hairs and less hair loss. When researchers combined the three most comparable studies in 2025, the difference compared to placebo was not statistically significant. The direction is correct, but the evidentiary value is limited.
Is adenosine better than minoxidil?
No, based on the evidence, it is not. Minoxidil is an approved drug with many large studies. In one Iranian study, 0.75% adenosine performed no worse than 5% minoxidil, and men were more satisfied with it, but recovery was low in both groups. Adenosine does win on tolerability: less irritation and, as far as is known, no shedding phase.
Can you use adenosine and minoxidil at the same time?
Yes, you can, and there are no known risks to the combination. They work via a different route: minoxidil via potassium channels and blood flow, adenosine via the A2B receptor in the dermal papilla. However, there is no study that has measured whether the combination yields more than minoxidil alone. Preferably apply them at different times so that your scalp does not become too wet.
Does caffeine cancel out the effect of adenosine?
That is not known, as no one has investigated it on the scalp. In theory, caffeine blocks adenosine receptors, just like in your brain. But in the hair follicle, caffeine primarily works by inhibiting the breakdown of cAMP, and adenosine actually increases cAMP. In that respect, they push in the same direction. Whether there is any interference in practice remains for future research to show.
What concentration of adenosine do you need?
Most studies involved 0.75% adenosine in a lotion that remained on the scalp. No research shows what the lowest effective concentration is. Manufacturers rarely state the percentage. Look at the ingredient list to see where adenosine is positioned and remember that a shampoo you rinse out has less time to have an effect than a serum.
Does adenosine have side effects?
Adenosine on the scalp rarely causes side effects. Most studies reported none. In the comparison with minoxidil, 3.8% of adenosine users had a complaint, compared to 9.8% with minoxidil. Because it is a naturally occurring substance, it is considered safe. If you do experience itching or redness, stop and see if another ingredient in the product is the cause.
How long does it take before you notice anything from adenosine?
Count on at least four to six months. In all studies, the effect was only measured after six months, and in one even after twelve. This is due to the hair growth cycle: a hair that enters the growth phase now will only be visibly longer and thicker after months. Men in the study against minoxidil did indicate that they noticed less hair loss sooner, but that was their own subjective assessment.
Does adenosine inhibit DHT?
No, adenosine does not lower your DHT like finasteride does. It works on the cells in the dermal papilla and supports the growth phase there. There is a small study on a complex with adenosine that suggests an effect on the androgen receptor, but that involved a mixture of substances. If you really want to tackle DHT, you need something else or a combination.
Does a shampoo with adenosine work just as well as a lotion?
Probably not. Almost all research has been conducted with a lotion that stays on the scalp. You rinse a shampoo away after a minute, so much less adenosine reaches the hair follicle. There is one study with a shampoo containing adenosine and caffeine, but without a control group. So, see a shampoo as a supplement, not as a treatment.
