Peel and chop one or two medium-sized onions. Blend the chopped onions in a blender or food processor until you get a smooth paste.
 

You can enhance the effectiveness of onion juice by mixing it with other ingredients such as honey, olive oil, or coconut oil. 
 

Part your hair into sections to ensure even application.

Using a cotton ball or applicator brush, apply the onion juice directly to your scalp. Massage the scalp gently with your fingertips for a few minutes.

Once the scalp is thoroughly covered, leave the onion juice on for about 15-30 minutes. You can cover your hair with a shower cap to prevent dripping and enhance absorption.

After the recommended time, rinse your hair and scalp thoroughly with lukewarm water. You may use a mild shampoo to remove the onion smell if desired.