A tattoo is a permanent mark on the skin made by piercing the skin with needles and introducing pigment. Tattooing is considered generally safe when done by an experienced tattooist who sterilizes equipment and follows proper sanitary practices, and if appropriate care is taken during the healing process. However, getting a tattoo involves perforating the skin--one of the body's principal protections against disease. If not done safely, this can cause life-threatening infections. According to the U.S. Centers for Disease Control, human immunodeficiency virus (HIV), hepatitis B virus, and other blood-borne infections may be transmitted if blood-contaminated instruments are not properly sterilized or disinfected. The American Red Cross refuses donations of blood from anyone who has undergone tattooing during the previous year. There is also a risk of an allergic reaction to tattoo pigment. In some cases, large, thick scars (sarcoid-like granulomas) have formed at a tattoo site...