As henna is a natural ingredient, there is a small chance that an allergic reaction could occur during the treatment. We would strongly recommend popping in for a quick patch test 48 before your Henna Brows booking, just for peace of mind–and if you experience any discomfort, just let us know! This is especially recommended if you have a strong history of allergic reactions. Even if you have had henna treatments before, a patch test is the best way to ensure you will love your Henna Brows.