The same onion benefits that make it great for your face extend to your scalp and hair too! Onions have long been used as a treatment for thinning hair and they help to alleviate dandruff while leaving your tresses shiny and silky. Mix equal parts onion juice and coconut oil, honey or olive oil. Coat your hair and let it sit anywhere from one hour to overnight. Rinse with warm water. Onion juice and alum can be applied directly to your scalp to relieve dandruff. If you don’t feel like messing around with DIY hair treatments, Babushka Agafia’s 100% natural Restorative Hair Mask with Egg Yolk, Onion & Burdock Root Oil is only $11.