Hair
Onion Juice for Hair Regrowth
One small 2002 trial in alopecia areata — a different disease from male-pattern loss — found regrowth. Nothing supports it for the loss most people have.
Also called: onion juice hair · onion scalp
Verdict — mixed
Real in part — the claim outruns what it actually does.
Evidence grade D
Nobody has demonstrated this works. Note that this grades the evidence, not the danger — read the verdict for that.
Mechanism
Sulphur compounds and quercetin proposed as antioxidant and irritant stimuli; alopecia areata is autoimmune, so a local irritant plausibly acts on that mechanism and not on androgenetic miniaturisation.
Citations
- Onion juice (Allium cepa L.), a new topical treatment for alopecia areataJournal of Dermatology · 2002
The full read
The citation is real and is being applied to the wrong condition. Alopecia areata is patchy autoimmune loss with a high spontaneous remission rate, and topical irritants are an established (if crude) treatment class for it — so a small uncontrolled-ish trial showing regrowth is unsurprising and says nothing about DHT-driven pattern loss. For androgenetic alopecia there is no evidence at all. Downsides are limited to contact dermatitis and smelling like an onion. If your loss is patchy and sudden rather than gradual and patterned, see a dermatologist — that is a different diagnosis with real treatments.
