Nine clinical trials, fragile evidence
Review2025 systematic review9 trials684 people
All the trials conclude in favor of caffeine on hair shedding or thinning, but the level of evidence is moderate for 3 trials, low for 1 and very low for 5. Many have no randomization, no placebo and no stated concentration. The authors call for better trials on well-defined products3.
Cultured follicles: growth stimulated
LaboratoryCultured human folliclesCaffeine 0.001 to 0.005%In the presence of testosterone
Caffeine offsets the slowing of growth caused by testosterone4. It also lengthens the growth phase and stimulates the proliferation of hair matrix cells, with a stronger sensitivity in female follicles5.
Caffeine and adenosine shampoo
Clinical trialCaffeine and adenosine shampoo3 months77 peopleComparison with baseline, no control group
Hair density increases and shedding decreases compared with baseline; hair diameter does not change significantly. 71.05% of participants say they are satisfied. Combination of two actives6.
DMG-Na and caffeine shampoo
Clinical trialDMG-Na and caffeine shampoo24 weeks154 menDouble-blind, placebo-controlled
The number of hairs pulled out in the pull test drops by 2.8 on average, against a rise of 0.6 under placebo (p < 0.001). In 30 subjects, the phototrichogram shows more hairs, higher density and more hairs in the growth phase. Combination of two actives: the effect of caffeine alone is not isolated7.
Healthier-looking scalp, less hair shedding
Clinical trialShampoo and leave-on product24 weeksDouble-blind, placebo-controlled
A combination of niacinamide, panthenol, caffeine, piroctone olamine and zinc improved scalp condition and reduced hair shedding. The effect of caffeine on its own is not isolated8.