Coral inhabits the tropical and subtropical waters of the world and consists of colonies of marine animals that have calcified outer skeletons. There are approximately 1,000 species of coral.

Accidental contact with coral often results in abrasions or superficial lacerations that are contaminated with small amounts of animal protein and calcium carbonate material. Some corals contain stinging cells (nematocysts), which can result in envenomation and more significant injury (see fire coral sting).

Superficial coral injury typically causes a stinging pain, erythema, pruritus, and a wheal at the wound site, called "coral poisoning." If properly treated, local symptoms may last a day or two. However, even with proper treatment, the wound may develop into a festering sore, ulcer, or cellulitis with lymphangitis that may take 3-6 weeks to heal. Chronic ulceration, necrosis, osteomyelitis, and lichenoid dermatitis may develop.

Low-grade fever in the absence of infection is not uncommon.