Onion Juice for Hair Growth Is BeautyTok’s Latest Obsession—but Does It Work?

Anyone with very sensitive or eczema-prone skin should proceed with extra caution, Dr. Foad says, since undiluted onion juice can cause itching and irritation. If that’s you, rosemary oil might be a safer addition to your routine; it’s also linked to certain hair-growth benefits, and its composition is more soothing.

In terms of hair type, “curly or coarse hair may tolerate [onion juice] better, though pairing it with a calming ingredient like aloe vera or a lightweight oil helps offset dryness,” Dr. Foad says. It’s important to remember that the effects of using onion juice may vary, even in individuals with similar hair types and scalp conditions. But when used thoughtfully, it can be a helpful addition to your routine.

Should I start chopping at home, or look for products with onion juice?

Dr. Foad says, “Both approaches can offer benefits, but they’re not the same experience.” Rinsing your scalp with homemade onion juice—made from puréeing red onions and straining the concoction down to a thin juice—“delivers the onion’s nutrients directly to the scalp” but can also be messy, strongly scented, and irritating if not diluted properly with water and other ingredients, Dr. Foad says.

Yates recommends adding argan oil, sandalwood oil, and rice water for complementary, hydrating benefits if you’re making onion juice at home. Importantly, if you’re experimenting with your own mixture, “always patch-test first and use it sparingly to see how your skin responds,” Dr. Foad says.

If the DIY route sounds like an ordeal, Dr. Foad says that professionally formulated products with onion extract tend to be much easier and more stable. Plus, they often include hydrating and soothing ingredients to pad out your tolerance. “For most people, a store-bought product is the more practical starting point,” Dr. Foad says.

How often should you use onion juice for best results?

According to Dr. Foad, consistency matters more than frequency. Generally, she says, using a well-diluted home concoction or a product containing onion juice two to three times weekly will allow you to reap the benefits without overwhelming your scalp. Daily use definitely isn’t necessary and will likely lead to irritation. For more-concentrated homemade juice concoctions, Yates advises even more sparing use—once every other week maximum.