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Quick Answer
No, onion juice cannot turn existing grey hair back to its original colour. It is a popular home remedy, but there is no scientific evidence that applying it to the scalp can bring the natural colour of grey hair back.
Grey hair can appear earlier than expected for many reasons, like family history and certain nutritional or health-related factors. When looking for premature greying home remedies, many individuals turn to household ingredients like onion juice. This is because onions contain several plant compounds that may have antioxidant properties.
However, this does not mean that applying onion juice can bring colour back to grey hair. There are no studies that claim onion juice as a solution to premature greying.
Why Onion Juice Cannot Fix the Causes of Premature Greying
Onion juice cannot fix premature greying because it works only on the surface of your hair. Hair colour loss, on the other hand, happens deep inside the hair follicle due to internal biological processes. Hair colour is produced by cells called melanocytes, which shut down due to internal factors, and topical onion juice cannot reach or repair cells in the hair follicles.
Topical onion juice cannot solve these primary causes of early greying:
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Family history: If close family members developed grey hair early, you may be more likely to experience it too.
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Nutritional deficiencies: Low levels of certain nutrients, including vitamin B12, have been associated with premature greying in some studies.
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Thyroid problems: Changes in thyroid function may occur alongside premature greying in some people.
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Smoking: Smoking has been associated with earlier greying and may contribute to oxidative stress that can result in premature greying.
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Natural changes with age: Hair gradually produces less pigment as we get older.
Why Do People Believe Onion Juice Works for Grey Hair?
The idea that onion juice may help grey hair mainly comes from claims about antioxidants and an enzyme called catalase found in onions. Catalase helps break down hydrogen peroxide, which can cause oxidative stress to your hair.
While onion juice can help support healthy hair, there is no relation between onion juice and supporting hair pigment.
The composition of onion juice can help your hair in the following ways:
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Antioxidants in onions: Onions contain compounds that may help protect cells, but this has not been shown to reverse grey hair.
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Sulphur in onions: The sulphur compound in onions supports keratin, which is the building block of hair strands, thereby strengthening your hair.
What Onion Juice Can Do For Your Hair?
Onion juice may be used as a home scalp-care treatment, but there is not enough evidence to say that it improves hair colour or promotes hair growth. Most of the attention around onion juice comes from its traditional use and limited research into other hair concerns.
To help set realistic expectations, the table below outlines the scalp benefits of topical onion juice alongside its physical limitations with regard to hair pigmentation:
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What it can do: |
What it cannot do: |
|
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How it compares to other remedies: Like plant oils or herbal teas, onion juice acts as a basic scalp wash, whereas altering hair colour requires external dyes or internal nutritional support.
How to Apply Onion Juice Safely and Avoid Side Effects?
To apply onion juice safely, test a drop on your arm first, apply a small amount directly to your scalp for 15 minutes, and wash thoroughly with a mild shampoo. Because raw onion juice contains strong sulfur compounds, it can irritate your scalp.
Before applying raw onion juice to your scalp, follow these five step-by-step precautions to minimise chemical irritation from sulfur compounds:
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Place one drop of fresh juice behind your ear and wait a full day to check for redness, itching, or burning.
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Blend a raw onion, squeeze the liquid through a fine cloth, and throw away the solid pieces.
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Use a small cotton ball to dab tiny drops onto your scalp instead of soaking your hair strands.
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Leave the juice on your scalp for no longer than 15 to 20 minutes to prevent skin redness.
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Wash your head completely with a gentle shampoo to remove all lingering onion juice and strong odours.
Drawbacks and Risks of Using Onion Juice on Hair
Undiluted application of raw onion juice may cause scalp sensitivity or mild redness, dry hair strands, and a strong smell that lingers for days.
Understanding potential side effects helps ensure safe application while protecting your scalp health:
|
Drawback |
What Happens to Your Scalp |
How to Handle It |
|
Scalp Burning and Redness |
Strong sulfur in raw onions may cause temporary skin irritation or itching in sensitive scalps. |
Dilute the juice with plain water or soothing aloe vera gel |
|
Lingering Bad Odour |
Sulfur compounds stick to hair proteins even after washing |
Wash your hair using a deep-cleaning, scented shampoo |
|
Eye Stinging |
Volatile onion fumes irritate delicate eye tissues during rinsing |
Lean your head backwards while washing so that traces of the juice do not flow to your face |
|
Dry Hair Strands |
Raw onion juice strips away natural protective scalp oils |
Apply a lightweight conditioner to your hair ends right after washing |
Understanding Premature Greying and Hair Health
Although onion juice may be a common solution for greying hair, there is no scientific basis at present to suggest that using it will be an effective solution for greying hair. Hair pigmentation is affected by multiple biological mechanisms, and causes for early greying are diverse.
It would be more beneficial to get knowledge about your general hair and scalp issues rather than relying only on a specific solution. If you are facing greying along with other problems of your hair, then seeking professional help could prove beneficial.
Unsure why your hair is greying early?
Take Traya's free Hair Test to better understand your hair concerns and explore a personalised, doctor-backed approach to hair care.
Frequently Asked Questions
How do I reverse my premature grey hair?
No technique has been scientifically proven to turn grey hair black again. When greying happens prematurely, recognising any causes that could have contributed to the situation can be beneficial.
What are the disadvantages of onion juice on hair?
Onion juice might cause itching and reddening of the skin in certain people. The pungent smell of onion juice can sometimes be hard to wash away too. Therefore, a patch test should be performed before using onion juice on the scalp.
Can I apply onion juice directly on hair?
Certainly, a little onion juice can be used on the scalp after doing a patch test, but in case of any irritation, stop using it and do not treat it as a remedy to restore the colour of your grey hair.
Does onion juice reverse premature greying?
No, onion juice cannot reverse premature greying or turn existing grey hair back to its original colour. There is currently no good evidence that applying onion juice to the scalp can restart the process that gives hair its natural colour.
References:
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Wood, J. M., Decker, H., Hartmann, H., Chavan, B., Rokos, H., Spencer, J. D., Hasse, S., Thornton, M. J., Shalbaf, M., Paus, R., & Schallreuter, K. U. (2009). Senile hair graying: H2O2-mediated oxidative stress affects human hair color by blunting methionine sulfoxide repair. The FASEB Journal, 23(7), 2065–2075. https://doi.org/10.1096/fj.08-125435
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