Cardi B Uses Onion Water for Hair Growth, So Naturally, We Asked an Expert If It Works

When it comes to whipping up hair remedies at home, we usually opt for commonly used ingredients that are already in our kitchen (e.g. honey, coconut oil and eggs). However, recently, Cardi B surprised us all on Instagram when she revealed that she uses onion water for hair growth. While her Instagram photo showed proof of her impressively long locks, we still wanted to do our own research, so we reached out to a dermatologist to figure out if it’s actually worth trying ourselves. And folks, she might be on to something.

Meet the Expert:

Is onion water good for hair growth? 

Maybe. According to Dr. King, there isn’t enough science to back up this claim just yet. “There was one 2002 study that showed subjects with patchy alopecia areata who used an onion juice treatment and experienced more hair regrowth compared to those who used tap water. However, this was a small study, and it was for alopecia areata—which is not the most common type of hair loss,” explains Dr. King.

However, onion water does contain high levels of vitamins and minerals. Dr. King points out one key component found in the allium—sulfur—has been proven to clear the scalp, restore hair follicles and minimize thinning over time. The liquid also contains antiseptic, antimicrobial and anti-inflammatory properties to further stimulate the scalp, promote blood circulation and strengthen your strands. 

Are there any other benefits to onion water aside from hair growth? 

While the Grammy award winner praised onion water for hair growth, the ingredient also has a few other benefits like:

  • Preventing premature graying. Now it’s not going to stop strands from turning gray or reverse the graying altogether (though there’s nothing wrong with showing off your silver). However, it does have an antioxidant called catalase that’s been known to break down hydrogen peroxide found in hair follicles into water and oxygen. This separation can slow down the process of your strands turning gray. 
  • Keeping the scalp clean and healthy. As mentioned, its antibacterial properties clear up excess oil, dirt and bacteria from the scalp. It also holds anti-inflammatory properties that soothe and reduce any itchiness.
  • Controlling dandruff. The antimicrobial and antifungal properties of onion water can reduce dandruff. “​​There are several organic acids found in onions, including glutamic, oxalic, pyruvic, malic, tartaric, citric and fumaric acids. These compounds can provide gentle chemical exfoliation of the scalp, which may help improve dandruff,” Dr. King adds. Note: If you have severe dandruff, it’s best to consult with a medical professional first. 
  • Adding moisture, shine and volume to hair. Antioxidants found in onion water help boost moisture and shine, while also bringing back shape to limp strands. 

What are the side effects of using onion water on your hair?

OK, let’s address the elephant in the room: the scent. It doesn’t have the best fragrance, so if you’re sensitive to smells, we say sit this one out. (Although there are some ways to reduce the scent that we’ll touch on later.)

If you’re allergic to onions, skip this DIY altogether. Plus, the acidic nature of onions might be too much for people with sensitive skin. If you do decide to try it, Dr. King suggests adding in soothing ingredients like aloe vera to combat redness and dryness. But if any skin reaction occurs, stop use immediately.

How to Use Onion Water for Hair Growth

How do you make onion water?  

Now that you’re on board, here are two methods to make your own onion water at home:

  1. Squeezing Method. Grab one onion (any type will do) and peel it before chopping it into small pieces. Gather the small bits of onion and blend them for a few minutes until they form a paste-like texture. Then, pour the mixture into a muslin cloth and squeeze the juice into a bowl.
  2. Boiling Method: Cut any onion into medium-size pieces and add the bits into a pot of boiling water (about two cups). Wait ten minutes before straining the liquid into a bowl.

If you’re looking to store your fresh onion juice, put it in an airtight container and pop it into the fridge for up to five days.

How should you use onion water?

Add a tablespoon or two of onion juice to your favorite shampoo and wash your hair as you normally would. Or try it as a pre-wash mask instead by applying onion water directly onto your scalp and letting it sit for 15 to 30 minutes before rinsing and continuing with the rest of your haircare routine. 

If you want to spice things up, add more ingredients to your mixture. Popular additions like coconut oil, olive oil and honey provide a greater chance of hair growth, and boost its moisturizing and strengthening effects. Add one tablespoon of onion water to your ingredients of choice, massage the mixture into the scalp and wait 30 minutes to an hour (or even overnight) before rinsing. 

OK, but what about the smell? Adding in ingredients like lemon juice, rose water and apple cider vinegar can help mask the potent scent and promote a healthy scalp. Add one tablespoon of your chosen ingredient to one tablespoon of onion water. You can also include a few drops of an essential oil (we’d suggest tea tree oil, peppermint or lavender) to further reduce the chances of smelling like an onion.

How often should you use onion water?

Dr. King recommends using onion water one to three times a week—and even wearing it overnight (if you can handle the smell). While Cardi B didn't specify how often (or for how long) she's been doing this, one PureWow writer put it to the test for a couple of weeks. After adding onion water to her shampoo once a week, she started to see some fullness coming in around her hairline. 

One last thing…

There are many factors that can lead to hair thinning and shedding. On that note, please be patient with yourself (and your strands). While onion water may work for Cardi B, remember that it takes time to grow hair and it may require some trial-and-error to find what works best for you.

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Associate Editor, Ultimate Fangirl, Aspiring Beauty Guru

Chelsea Candelario is an Associate Editor at PureWow. She has been covering beauty, culture, fashion and entertainment for over a decade. You'll find her searching the internet...