Encyclopedia · growth stimulant
Topical cetirizine
The common allergy antihistamine, made up as a 1% scalp solution, has several small trials suggesting a modest effect that is weaker than minoxidil.
What it is
Cetirizine is an antihistamine sold over the counter in many countries. A 1% scalp solution is not a licensed product; it is compounded or made by research groups, and it is not approved for hair anywhere.
The rationale: prostaglandin D2 (PGD2) is raised in bald scalp and inhibits hair growth in cultured follicles and mice, and cetirizine is said to lower PGD2 and raise the pro-growth PGE2 (Garza 2012).
How it works
Proposed: dampening PGD2 signalling in the scalp. The 2012 work showed the pathway in human tissue and mice, not that cetirizine acts this way in people. The oral PGD2-receptor blocker setipiprant failed in a phase 2 trial, which weakens the case without disproving it.
What the studies show
- 40 men used 1% cetirizine or 5% minoxidil twice daily for 16 weeks. Both raised hair density, but minoxidil's improvement was much higher (Hossein Mostafa 2021).
- A systematic review of three trials judged cetirizine likely better than placebo and less effective than minoxidil for density, with moderate-to-high risk of bias (Chen 2022).
- In 66 women on minoxidil, adding cetirizine for 24 weeks gave thicker hair shafts and better self-rating than adding placebo (Bassiouny 2023).
- In 80 men, microneedling with cetirizine gave vellus hair prevalence of 70% versus 30% with saline over 8 weeks, and density improved in 80% versus 25% (Gohary 2025).
- An uncontrolled pilot of 10 men found hair count in a 1 cm2 area rose from 139.6 to 163.4 over 16 weeks (P=0.009), but blinded photos improved in only 3 of 9 (Dhurat 2025).
- In 62 people, adding cetirizine to minoxidil made no significant difference in density, diameter or photo scores over 16 weeks, though satisfaction was higher (Mokhtari 2026).
- All trials are small and short (8 to 24 weeks), several single-blind. The positive add-on result in women and the null add-on result are typical of this literature.
How it's used in studies
- 1% cetirizine in a glycol vehicle, 1 mL daily or twice daily for 16 weeks; also delivered by microneedling for 8 weeks.
Side effects and safety
- No significant adverse reactions were reported in these trials. Systemic absorption is not well characterised.
Bottom line
A low-risk experiment for people who cannot use minoxidil, but weaker than minoxidil in the only head-to-head trial and unproven as an add-on. It is not a replacement for proven treatments. Discuss with a doctor.
Studies 7
Garza LA et al. Prostaglandin D2 inhibits hair growth and is elevated in bald scalp of men with androgenetic alopecia. Sci Transl Med. 2012
Tested: PGD2 measurement and exposure
Result: PGD2 was higher in bald scalp and inhibited hair growth in cultured follicles and mice through the GPR44 receptor.
Read the study ↗Hossein Mostafa D et al. Efficacy of cetirizine 1% versus minoxidil 5% topical solution in the treatment of male alopecia. J Pharm Pharm Sci. 2021
Tested: cetirizine 1% vs minoxidil 5%, twice daily
Result: Both raised hair density, but the improvement was much higher with minoxidil.
Read the study ↗Chen X et al. Topical cetirizine for treating androgenetic alopecia: a systematic review. J Cosmet Dermatol. 2022
Tested: topical cetirizine
Result: Likely better than placebo but less effective than minoxidil for density, with moderate-to-high risk of bias.
Read the study ↗Bassiouny EA et al. Topical cetirizine with minoxidil versus topical placebo with minoxidil in female androgenetic alopecia. Arch Dermatol Res. 2023
Tested: minoxidil plus cetirizine vs minoxidil plus placebo
Result: Cetirizine gave thicker hair shafts and better self-rating; side effects were similar.
Read the study ↗Gohary YM et al. The efficacy of topical cetirizine using microneedling in androgenetic alopecia male patients. Arch Dermatol Res. 2025
Tested: microneedling with cetirizine vs saline
Result: Vellus hair prevalence was 70% vs 30% and density improved in 80% vs 25%.
Read the study ↗Dhurat RS et al. Topical cetirizine in androgenetic alopecia: a preliminary study. Skin Appendage Disord. 2025
Tested: 1 mL of 1% cetirizine daily
Result: Hair count in a 1 cm2 area rose from 139.6 to 163.4 (P=0.009); blinded photos improved in 3 of 9.
Read the study ↗Show 1 more studies
Mokhtari F et al. Clinical outcomes of adding topical cetirizine to minoxidil therapy in patients with androgenetic alopecia. J Res Pharm Pract. 2026
Tested: minoxidil plus cetirizine vs minoxidil alone
Result: No significant difference in density, diameter or global photo scores; satisfaction was higher with cetirizine.
Read the study ↗Related
- MinoxidilThe most widely used hair-growth treatment, available as a cheap over-the-counter lotion or foam and as a prescription tablet, with a mechanism that is still only partly understood.
- SetipiprantAn oral blocker of the PGD2 receptor GPR44 that was tested for male pattern baldness on strong lab data and grew no more hair than placebo in 169 men.
- LatanoprostA cheap glaucoma eye drop that lengthens and darkens eyelashes, with only a small pilot trial behind its off-label use on the scalp.
- Microneedling for hair lossRolling or stamping fine needles into the scalp is a cheap add-on to minoxidil that helped in small trials, but it has not worked on its own and the largest trial found no extra benefit.
- Prostaglandins and hairProstaglandins are fat-derived signals that switch follicles on or off; eye drops that copy one of them grow eyelashes but have not worked on the scalp.