What hydrogen peroxide really does to your hair

There’s another serious issue that can potentially be caused by hydrogen peroxide. The Journal of Dermatological Science (via the United States Environmental Protection Agency) reports that hair dye and hydrogen peroxide are also known causes of dermatitis. Worse still, L’Oreal refers to the United States National Library of Medicine, which believes hydrogen peroxide may even cause scalp burn.

However, it’s important to note that if hydrogen peroxide is used correctly, both at home and in the salon, there should be no side effects. If you want to be extra cautious Danielle Llewellyn, the UK Hair Ambassador for eSalon, recommends opting for quality hair dye products. Look for “a high-quality dye that will prevent damage, rather than cause it,” she told Harper’s Bazaar. She also adds that aftercare is key. “Always wash your hair with a shampoo and conditioner designed for color-treated hair as color-safe products are gentle and don’t strip out moisture like sulphate-laden types do.”