Summarize this article in one sentence.
The Food and Drug Administration, or FDA, has received multiple reports from consumers who experienced long-lasting and severe side effects from the application of henna for temporary tattoos. Side effects include, but are not limited to, red lesions that are raised and weeping, loss of pigmentation of the skin, blisters, increased sunlight sensitivity, redness, and permanent scarring.  These reactions can occur immediately after getting a temporary tattoo using traditional red henna or "black henna." Reactions from temporary henna tattoos can also occur up to two or three weeks after receiving the tattoo. You can also experience adverse side effects from hair dye that contains “black henna.” If you are purchasing henna to use at home on your skin or hair, make sure you examine each ingredient listed on the label. Avoid any color additives in henna dyes to be used on the skin. If you are getting a henna tattoo from a tattoo artist or your hair dyed by a professional, make sure you inquire about the ingredients in the dye they will use on your skin or hair. Ask specifically about the inclusion of p-phenylenediamine, or PPD, and avoid getting a tattoo with this additive. Children can be particularly sensitive to henna. Skin sensitivities and allergic reactions to henna can occur in children.  Children with glucose-6-phosphate dehydrogenase deficiency are at particular risk, as applying henna to the skin of children with this condition can cause a life-threatening condition called hemolysis. Seek immediate medical attention if a child with glucose-6-phosphate dehydrogenase deficiency has been exposed to henna.

Summary:
Understand that using henna on your skin or hair is not necessarily safe. Read product labels carefully. Avoid using henna on all children.