Does Cardi B’s Onion Water Hair Hack Actually Improve Hair Growth?

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Cardi B is no stranger to sharing her hair hacks with the world. The singer previously took to Instagram Stories to reveal the DIY hair mask she credits with keeping her hair healthy, with the key ingredients of the mask being avocado, mayo, banana, egg, and a blend of nourishing hair oils—nothing unusual for an at-home hair mask. But more recently, she shared in an Instagram Post she’s been loving a truly unexpected liquid for shiny, healthy hair. Cardi B teased a “vegetable water” on social media, revealing the secret vegetable was none other than onion. Turns out, onion water is all the “Up” singer needs to achieve her hair goals. Safe to say we did not have this on our 2022 bingo card.

We’ve heard of the benefits of onion oil for hair but also wanted to learn more about onion water. We reached out to hair care expert Tiffany St. Bernard, Ph.D., to learn more about this interesting hack for healthy hair. Along with a rundown of the elixir’s benefits, Dr. St. Bernard shared how to make onion water and we even rounded up some of our favorite onion-based hair care products. Scroll below for everything you need to know!

About the Expert

Tiffany St. Bernard is a hair care expert with a Ph.D. from Cornell Biomedical Engineering. She is also the CEO of Hairdays, an AI-powered hair care community.

Onion Water Hair Benefits

1. It promotes stronger hair.

Dr. St. Bernard shares that “onions are high in sulfur which is found in amino acids that are key components of protein. Proteins are essential for hair growth, specifically the sulfur-rich protein keratin.” Because of this, onion water can promote stronger hair growth and thicker strands.

2. It stimulates collagen production.

Another benefit of an onion’s high sulfur content? It can help stimulate collagen production, as sulfur is necessary for the formulation of collagen. “Collagen is a key factor in the production of healthy skin and hair cells,” notes Dr. St. Bernard. For those who aren’t familiar with the benefits of collagen for hair, the protein is known to aid in increasing elasticity, moisturizing, promoting hair growth, and regenerating the hair follicle.

3. It increases blood circulation on the scalp.

Increased blood flow and circulation on the scalp are the building blocks for healthy hair. After all, the health of your scalp directly impacts the health of your hair. Dr. St. Bernard reminds us of this by mentioning that “increased circulation delivers more blood flow to the follicles and promotes stronger hair growth.”

She notes that it isn’t solely possible to reap these benefits by rinsing your hair with onion water, but also by eating some onions. “These increased circulatory benefits can be seen by ingesting onion juice, with about four to five grams daily shown to improve blood flow in the body.” Of course, don’t feel pressured to down a bunch of onion juice. You can get the same benefits by adding more onions to your diet. French onion soup, anyone?

4. It aids in hair growth.

All of the above benefits are the reason onion water helps aid in the hair growth process. “Providing the right nutrients and blood flow to follicles during the growing phase helps to extend the life cycle of the hair follicles with the result being longer and healthier strands,” Dr. St. Bernard reveals.

How to Use Onion Water for Hair Growth

Dr. St. Bernard shares that using onion water as a pre-washing treatment is the best way to reap its benefits. “Apply the onion water to your scalp prior to washing, let the onion water sit on your scalp and follicles for an extended period of time, and then wash and condition your hair as normal afterward,” she says. The amount of time you keep the rinse on will vary depending on your hair type and thickness, though Dr. St. Bernard does stress the importance of a patch test beforehand. Apply a small amount of onion water to part of your hair and scalp to see if any irritation occurs. If it does, immediately rinse it out.

Creating onion water for your hair is a pretty simple process. Dr. St. Bernard breaks it down step-by-step below:

  1. Peel and slice onions before putting them into a blender to make a juice.
  1. Take a few other onion pieces and grind them down into a paste.
  1. Add a carrier oil and your onion juice/paste to a saucepan.
  1. Bring this to a boil and then reduce heat and let simmer until the oil separates.
  1. Turn off the heat and let this mixture cool for several hours.
  1. Use cheesecloth or a strainer to strain out the oil, and then store in an airtight container to use as needed.

Should you not want to rinse your hair with onion water or even go through the trouble of making it, eating onions is always an option. Dr. St. Bernard notes you can still reap all the benefits by eating onions.

What to Know Before Using Onion Water for Hair

Those who are allergic to onions should avoid using onion water for hair growth. If you’re unsure whether or not you’re allergic, see a doctor. And, as previously mentioned, perform a patch test to ensure no irritation will occur.

To see results, you will need to use it consistently—but when you see the results will vary from person to person. Some will notice the positive effects sooner than others (even in as little as two weeks), while others may require a little more time using the concoction (more than a month). It will likely take an average of three to four weeks for results to show.

Though Dr. St. Bernard highlights the numerous benefits of onion water for hair and notes it can be used for any hair type, she doesn’t recommend it be used as a treatment method for serious hair health issues. “Treatment plans for serious medical problems should be done in consultation with a medical professional and be tailored to an understanding of your unique situation,” she shares. “Onion water can help to promote a healthy environment for your hair and scalp, but is not a cure for serious ailments.”

Our Favorite Onion-Based Hair Products

WOW Skin Science Onion Black Seed Hair Oil

Fortified with not only onion oil, but also almond, castor, coconut, jojoba, and olive oil, this hair oil is a cut above the rest. An expert blend of the best of the best oils, this mix will reverse damage, revitalize hair, and nourish and soften your strands. What more could you ask for?

WOW Skin Science Onion Black Seed Hair Oil | Mane Addicts
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Uhuru Naturals Onion Juice & Fermented Rice Water Elixir

This magical blend of rice water and onion juice offers a powerhouse of nutrients for a healthy scalp. And we all know that a healthy scalp means healthier hair. Simply spray it on before you wash your hair, let it sit for 10 minutes, then shampoo and condition as you normally would. You’ll notice a difference in no time.

Uhuru Naturals Onion Juice & Fermented Rice Water Elixir | Mane Addicts
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WOW Skin Science Red Onion Black Seed Oil Shampoo and Conditioner Set

Free of parabens and silicones, this shampoo and conditioner set is ideal for those who struggle with an itchy scalp. Red onion and black seed oil work overtime to remove buildup on the scalp leaving you with a clean canvas for your hair to grow. With an overall 4.2 star rating from over 1,700 Amazon reviews, you know this set is worth using.

WOW Skin Science Red Onion Black Seed Oil Shampoo and Conditioner Set | Mane Addicts
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Mamaearth’s Onion Hair Mask

This hair mask is meant to be used twice weekly to help reduce hair fall, repair damaged hair, and to make your hair thick and strong. Onion, organic bamboo vinegar, and coconut oil are the star ingredients of this mask, setting you up with all you need for better hair.

Mamaearth's Onion Hair Mask | Mane Addicts
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Onion water not your thing? Maybe rosemary water is more of your speed? Discover the benefits of this TikTok-raved hair rinse HERE!