I'm personally NOT a fan of tattoos--especially on a woman. It distracts from her natural beauty and I know it's just a personal preference. Getting a temporary henna tattoo can be a great way to express yourself or piss off your parents, but the joke may be on you if you’re not careful.
New FDA warnings have come out about how black henna ink containing para-phenylenediamine (PPD), which is a coal-tar product that they put in hair dye, can cause major damage to your skin.
Side effects from black henna include: redness, blisters, raised red weeping lesions (EW!), loss of pigmentation, increased sensitivity to sunlight, and even permanent scarring.
Some parents even said that their teens who got henna tattoos ended up looking like burn victims from the effects. Yikes. (Yahoo)