Once the paste is washed off the skin, the design will have dyed your skin orange. Over the next 24 to 48 hours, the design will gradually darken to a medium brown. Typically, the integrity of the design will last for 7 to 10 days. Remember, henna is permanent, but your skin is not. Our skin is constantly replenishing, so as your dermal layer begins to flake away, the henna will with it.