Encyclopedia · supplement
Para-aminobenzoic acid (PABA)
A 1950 physician report described gray hair darkening on high-dose PABA, and the idea has survived 75 years on weak evidence.
What it is
A B-vitamin-like compound that was an old sunscreen ingredient and appears in some supplements.
How it works
Unknown. A 2020 systematic review lists PABA among vitamins reported to darken gray hair, without a mechanism.
What the studies show
- A 1950 report titled "Darkening of gray hair during para-amino-benzoic acid therapy" is the origin of the idea; we read only the record. Zarafonetis 1950
- A systematic review of 27 studies found low-quality evidence that some B-vitamin supplementation (calcium pantothenate, PABA) can darken gray hair. Yale 2020
- A systematic review and meta-analysis of premature graying gave only a weak recommendation for calcium pantothenate, PABA and their combination. Mahendiratta 2020
How it's used in studies
Modern doses are not established, and we could not verify the old doses.
Side effects and safety
High oral doses cause nausea and can cause allergy. Pregnancy and drug interactions were not assessed.
Bottom line
Tiny historical reports and low-quality reviews. Fun history, no reliable evidence of benefit. The effect may reflect correction of a deficiency or the natural reversibility of some gray hairs (see gray hair).
Fun facts
- A 1950 journal report described gray hair darkening during PABA therapy, and a 2020 meta-analysis still gives it only a weak recommendation.
Studies 3
Zarafonetis CJD. Darkening of gray hair during para-amino-benzoic acid therapy. J Invest Dermatol. 1950
Result: Historical clinical report of gray hair darkening during PABA therapy (record only).
Read the study ↗Yale K et al. Medication-induced repigmentation of gray hair: a systematic review. Skin Appendage Disord. 2020
Result: Many drugs and some B vitamins were reported to repigment gray hair, mostly as incidental, low-quality reports.
Read the study ↗Mahendiratta S et al. Premature graying of hair: a systematic review and meta-analysis. 2020
Result: Low-grade (level 2A) recommendation for calcium pantothenate, PABA and the combination.
Read the study ↗Related
- Gray hair and premature grayingGraying is mostly genetic, but single-hair mapping shows some gray hairs can regain colour, and the famous stress-causes-gray mechanism has only been proven in mice.
- LuteolinA plant flavonoid sold as a supplement slowed hair graying in a mouse model while two similar antioxidants did not, and there is no human data at all.
- Catalase and pseudocatalaseThe idea that hair grays because follicles accumulate hydrogen peroxide has a real basis in vitiligo skin, but catalase supplements for gray hair have no human trial evidence.
- Drug-induced hair changesMedicines can thin hair, regrow it curly, darken or whiten it, or lengthen lashes; this table sorts the best-known links by how strong the evidence is.