Beauty Clean Slate Why Is Everyone Using Onion Oil for Their Hair? A deep-dive into TikTok’s latest hair hack. By Audrey Noble Audrey Noble Twitter Audrey Noble is NYC-based contributing beauty commerce writer. She covers all things beauty, hair products, and makeup. InStyle's editorial guidelines Published on February 17, 2023 @ 08:00AM Pin Share Tweet Email Getty Images. The universal craving for healthy hair is so strong that many will go to great lengths to get it. The latest example of this is the rise of at-home onion oil for hair. Yes, you read that correctly. If you’re on beauty TikTok like I am, chances are high you’ve seen many people taking an onion, boiling it, and making their very own at-home hair treatment all over the FYP. This begs the question: should we all be running to our local grocery stores or bodegas to stock up on onions? To get a better idea if this TikTok beauty hack is in fact legit or just another misleading trend, we turned to the experts. See them break down all you ever wanted to know about onion oil for your hair below. We Tested 29 Hair Oils — These 11 Keep Hair Moisturized and Silky Smooth What is onion hair oil? Onion hair oil, as explained by John Kahen, MD, chief hair surgeon and founder of Beverly Hills Hair Restoration, is the extracted juice from an onion that is applied on the scalp and hair. Dr. Kahen goes on to explain that while it’s blowing up now thanks to TikTok, this isn’t entirely new. “Some people have been using this as a natural at-home remedy for a long time, “ he says. “There have been products on the market that have used onion as an ingredient for a long time, as well.” He says that most people can use onion oil in their hair; there isn’t any specific hair type or length that should stay away from it. Instead, it’s all dependent on how your skin may react to onion (obviously, if you’re allergic to the vegetable you should avoid this entirely). He adds this treatment is best used for those who want to stimulate hair growth and increase volume in hair. Does using onion hair oil actually have benefits? There are some preliminary studies that suggest onion hair oil may help in hair loss and improve the health of hair and scalp. Dr. Garshick explains onions are rich in sulfur, which is thought to support and strengthen hair since the keratin found in hair also has sulfur. She adds that onion has antimicrobial and anti-inflammatory benefits, which may help maintain scalp health. Dr. Kahen adds that onions are rich in potassium, antioxidants, and amino acids. But more research needs to be done to definitively say that onion oil does in fact help with hair growth and health. “It’s important to remember that this may not work for all hair types and to have realistic expectations for an at-home remedy,” says Dr. Kahen. “You should also consult a hair expert or dermatologist before trying this.” Can you DIY onion hair oil? It turns out that the type of onion you use does kind of matter as they have different benefits. Marisa Garshick, MD, a board-certified dermatologist at MDCS Dermatology, explains that red onions have more antioxidants, which help stimulate hair growth and reduce shedding. White onion, she says has more sulfur, which is known to also help with hair growth and scalp conditions such as dandruff. Dr. Kahen says that there are varying techniques for extracting the juice and it can be used on its own or combined with a carrier oil like coconut or jojoba seed oil to make the application process easier. Many videos show users chopping an onion and boiling it to extract the juices before applying it directly on the scalp. Dr. Garshick adds that onion juice and its carrier oil can be mixed with other ingredients such as lemon juice to mask the odor or aloe vera to minimize irritation. Hair Oil vs. Hair Serum: Which One Is Better for You? Will onion hair oil make smell? The short answer to this is no — at least, not for long. It won’t make your hair smell like onions for hours after you use it if you rinse it off properly. Dr. Kahen says the smell is why he recommends using onion oil as a pre-shampoo treatment. He adds that if you mix in the oil with a carrier oil, it can dilute the smell significantly. Dr. Garshick adds that the smell can be masked with other ingredients such as lemon juice, but to be mindful that lemon juice can dry out the hair and scalp so use that sparingly. What's the best way to use onion hair oil? If you decide you want to give this treatment a try, Dr. Garshick says how often you do it will depend on your desired results and hair type. Generally speaking, she recommends using it one to two times a week. Dr. Kahen recommends applying the oil overnight or a few hours before showering to let it set in before rinsing out with your normal shower routine. The TL;DR on onion hair oil: While it can be safe to do for most, more studies need to be done to definitively say whether onion oil can actually help with overall hair and scalp health. If this has piqued your interest and you’re now wanting to try, do be careful and be sure to speak to a dermatologist before wasting an onion. From non-toxic makeup and skincare to sustainability practices, Clean Slate is an exploration of all things in the green beauty space. Find out what's really in your products — and what's being left out.