Herpes zoster (commonly referred to as “shingles”) and postherpetic neuralgia (PHN) is nerve damage that result from reactivation of the varicella-zoster virus acquired during the chickenpox (primary varicella infection). PHN is a form of neuropathic pain, which is chronic pain due to nerve damage. A variety of different diseases and conditions can cause neuropathic pain, including diabetes, shingles, trauma (injury or wound to the body) and diseases of the nervous system including Reflex Sympathetic Distrophy (RSD), also known as Reflex Sympathetic Distrophy Sydrome (RSDS). PHN and other neuropathic pain may be hot, burning, throbbing, shooting, stabbing, sharp, cramping, aching, tingling, or a pins and needles sensation. It is not the same for everyone, either. It may be mild or it may be severe. Some people feel pain all the time and it comes and goes in others.