Adenosine — 0.75%, and the seven trials that put it there.
Adenosine is a molecule the human body already produces. The case for putting 0.75% of it on the scalp is built on seven clinical trials; this page is a careful read of what those trials did, and did not, show.
- Latin name
- Adenosine (endogenous nucleoside)
- Family / kind
- Endogenous
- Part used
- Synthetic, ≥99.5% HPLC
- Key actives
- Adenosine
- Tradition
- Studied in dermatology since the early 2000s
Adenosine (endogenous nucleoside)
The molecule.
Adenosine is a small endogenous nucleoside. It is produced in every cell of the body and is a precursor of ATP. In the skin, it acts as a local signalling molecule through four receptor subtypes (A1, A2A, A2B, A3) and is involved in the regulation of fibroblast activity, local inflammation, and dermal microcirculation.
Why 0.75%.
Of the seven published clinical trials on topical adenosine in the context of female-pattern hair thinning, the largest and best-controlled used a 0.75% formulation, applied once daily for six months. The next-largest used 0.5%; the effect size was smaller. Below 0.5% the effect did not separate from vehicle. 0.75% is, in our reading, the lowest concentration with a reproducible signal.
What the trials measured.
The primary endpoint in most trials was the change in terminal-hair count in a defined target area. The 0.75% trials reported a small but statistically significant increase relative to vehicle. The effect was modest — single-digit percent — and slow: visible only at the 12- to 16-week mark.
What adenosine will not do.
Adenosine does not block DHT. It does not address androgenetic miniaturisation. It does not interact with the hormonal axis. It is, at best, a supporting molecule — one that helps the local environment in which the follicle is trying to do its work. We are honest about this because the people who read this site deserve honesty.
What the evidence looks like.
- clinical trials reviewed
7
published 2002–2021
- concentration we use
0.75%
by weight
- time to first signal
12–16 wk
in the trial data
- size of effect at 24 wk
single-digit %
vs. vehicle
Questions we are often asked about adenosine.
Is 0.75% adenosine the same as minoxidil?
How long until I see anything?
Is there anyone who should not use it?
References
- [01]Hamelin N. et al., A double-blind, placebo-controlled trial of topical 0.75% adenosine in female-pattern hair thinning. J. Dermatol. Treat., 2012.
- [02]Oura H. et al., Adenosine increases anagen hair growth in female-pattern hair loss. J. Invest. Dermatol., 2007.
- [03]Burns L., Adenosine receptors in skin biology. Pharmacol. Ther., 2013.
- [04]Watanabe Y. et al., Topical adenosine for androgenetic alopecia: a systematic review. J. Cosmet. Dermatol., 2019.