Onion juice has been a well-loved haircare ingredient for decades now, but it is only in the last few years that it has come to occupy center stage in the world of hair care. This potent ingredient can help with scalp infections, treat dandruff, and prevent premature greying of hair while making your hair shiny and lustrous at the same time. The high amount of sulfur in the onion juice is also known to stimulate hair growth. The benefits of using onion juice for hair are many. But should it be left on your hair overnight? This is what we'll answer in the following sections. We'll also explore the proper method of incorporating onion into your hair care regimen.
Table of contents:
- Can you leave the onion in your hair overnight?
- What happens if we leave onion juice on hair overnight?
- Can an onion damage hair?
- Should I shampoo my hair after applying onion juice?
- How many times should I apply onion juice to hair?
Can you leave the onion in your hair overnight?
It is generally not recommended to leave onion juice in your hair overnight.
For many people, the smell of onion oil can be a bit overwhelming, which is one reason they would avoid applying this haircare remedy overnight. Besides this, there is also a possibility that the overnight application of onion juice can result in a burning and itching sensation. Onion juice in its raw form is quite potent and can lead to skin irritations among some people. As a general rule of thumb, it is always advisable to test out onion juice on your hand or any other part of the skin to check for any signs of irritation.

What happens if we leave onion juice on hair overnight?
Onion juice is a powerful ingredient, well-known for its various benefits in hair care. It is jam-packed with several micronutrients like Vitamin B9, B6, Vitamin C, and Potassium, which helps in strengthening roots and making your tresses luscious and smooth. This potent ingredient can also help with scalp issues due to its antibacterial, anti-inflammatory, and antioxidant properties. But the proper application of onion juice is important if you want to see its full benefits. That means you have to apply the right amount of onion juice for a set duration for the recommended number of times.
The potency of onion juice comes from the rich sulfur content in this ingredient. If left on for longer, it can be too harsh for your scalp and hair. While the sulfur content does help in making hair stronger, it can also remove the necessary moisture from hair if left on overnight. The best way to apply onion juice to your hair is by leaving it on for 15 to 30 minutes. Ensure you wash it off with a mild, sulfate-free shampoo and normal water afterward.

Can an onion damage hair?
For the most part, onion is a powerhouse ingredient that can benefit your hair in several ways. The key lies in using it properly. As we stated, overuse of onion juice can lead to hair damage. Here is why –
- Onion juice contains a high concentration of sulfur, which can irritate the scalp in some conditions. If the onion juice is left on for longer and not washed off properly after application, it can cause itchy scalp and skin irritation. This is why washing the hair thoroughly after the onion juice application is recommended. This treatment should also be limited to once a week.
- Overusing onion juice can also lead to a dry scalp since it absorbs the natural oils and moisture from your scalp. With prolonged use of onion juice, you are also at a greater risk of developing scalp eczema, in which the scalp skin becomes itchy, dry, and inflamed.
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Onion juice has an unpleasant odor that can stay behind in your hair even after washing it off.
To avoid the damaging effects of onion juice, ensure you use it within recommended limits. It is also a good idea to try it in the form of an oil, conditioner, or hair mask when you are just starting. Here are our recommendations –
- Onion Black Seed Hair Oil With Almond, Castor, Jojoba, Olive & Coconut Oils
- Red Onion Black Seed Oil Shampoo And Conditioner
- Red Onion Black Seed Oil Hair Mask
Should I shampoo my hair after applying onion juice?
Onion juice is a wonderful hair care ingredient, but it is also laden with impurities in its raw form. If not washed off properly, these impurities can get attached to the scalp's skin, clogging the hair follicles. With every application, these impurities can accumulate on your scalp, allowing bacteria to thrive. All of this can be avoided by washing your hair properly after the onion juice application. Here are some tips for the same -
- Use a mild shampoo with clarifying properties, like the Wow Skin Science Activated Charcoal & Keratin Shampoo. Deeply cleanse your scalp using this shampoo and remove the pungent smell of onion juice from your hair.
- You can also rinse hair with diluted apple cider vinegar. If you are hesitant about using apple cider vinegar in its raw form, give Wow Skin Science Apple Cider Vinegar Shampoo a try.
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If, even after shampooing, there is a lingering smell of onion juice in your hair, you can add some essential oils to your shampoo. The Wow Skin Science Peppermint Essential Oil and Lemon Essential Oil are great options.
How many times should I apply onion juice to hair?
Onion juice should ideally be applied 1-2 times a week to your hair and not more. Since it is a little caustic in concentrated amounts, applying it directly on your skin can result in irritation and redness. Make sure to dilute the onion juice with water, green tea, coconut oil, or vitamin E oil. After applying it all over your scalp, massage it with your fingers for a few minutes and leave it on for 15 to 30 minutes (max 1 hour). After application, wash it with a mild, cleansing shampoo and lukewarm/cold water.
Onion oil and juice is an excellent remedy for all your hair woes, whether it's hair loss, dry hair, dandruff, or premature greying. But it's important to remember that excessive usage can irritate your scalp skin. Applying it 30 minutes before a shower can give you all the benefits of this potent ingredient. So, use wisely and watch your hair's health improve with onion oil.

To summarize, applying onion juice to your hair overnight is a no-no, especially if you have sensitive skin. If you do want to test out the benefits of the overnight application, maybe try a hair oil formulation like Wow Skin Science Onion Black Seed Hair Oil With Almond, Castor, Jojoba, Olive & Coconut Oils.
This hair oil also contains the goodness of several great oils that can provide your scalp with the necessary nourishment without causing any irritation. But most experts agree that you can get the same results by applying hair oils even 1 hour before showering. So, do you really want to apply onion oil overnight if you can get the same benefits in less time?
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