Can Onion Juice Really Make Your Hair Shinier?
A certain celebrity swears by this folk remedy
A few weeks ago, the beauty mags breathlessly reported that Cardi B uses water that has been boiled with onions and cooled to wash her hair. Could it be true? Indeed, the Bronx-born rapper, whose breakout hit was the 2017 chart-topper "Bodak Yellow," has been on a multiyear "healthy hair journey" that includes a regimen of washing her hair in onion water. The star posted before and after pictures on her Instagram in which her hair goes from looking frizzy and undone to smooth and sleek—and she credits onion juice for the shine.
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"Applying onions to the scalp is a very well-described method for treating hair for many years. Some say it causes hair loss, some say it cures hair loss," says Farjo. "What it does do is cause irritant effects on the scalp and therefore inflammation, which in turn causes a temporary increase of blood flow. It is well known that irritation of the scalp can cause temporary hair growth because of this."
There’s little research on the question, but a small 2002 study of a group of people with a type of hair loss known as alopecia areata found that those who applied onion juice to their hair saw more hair growth than a control group that applied plain tap water.
But, Farjo cautions that overuse of onion on hair can result in dryness, skin damage, and even eczema, which would mean the reverse effect: hair loss due to breakage. As far as shine goes, she has never encountered any scientific evidence to support Cardi B’s claim but concedes that the onion’s sulfur—the same chemical element that can make you cry when chopping them—could potentially have a smoothing effect on hair.
"The sulfur bonds that link hair fibers can be damaged in day-to-day weathering so potentially sulfur compounds in onions can repair these bonds which would make the hair look smoother and therefore potentially shinier," says Farjo.
Hair graying, meanwhile, is attributed to the lack of the catalase enzyme in pigment cells of the hair. Onions do contain catalase, but according to Farjo, pigment cells in hair lie below the skin’s surface at a level that cannot be penetrated by onion juice, and therefore could not turn back the clock on graying hair.
Farjo also warns against getting too caught up in the idea of natural remedies.
"The idea of using a “natural” substance for the hair or scalp is often promoted," she says. "However, natural products are made up of chemicals—some good and some bad. Remember that overuse of anything can be bad."
So there you have it. Next time you see a pic of Cardi B, say "Goals!" but check the facts before you try celebrity beauty hacks.
