Shingles (herpes zoster) is a painful, blistering skin rash caused by the varicella-zoster virus, the same virus that causes chickenpox. The first symptom is usually unilateral (one-sided) pain, tingling, or burning of the skin. This is followed by a red rash and then blisters. The blisters eventually break and form dry, crusty scabs on the skin. Some patients experience additional symptoms such as feeling ill, fever, or chills. Shingles is most common in older persons or those with immune systems weakened by medications or disease. Treatment is best if started early and includes antiviral medications to shorten the duration of the symptoms, as well as reduce the pain and complications of the condition. Some patients may have lingering symptoms such as chronic pain called post-herpetic neuralgia.