Herpes zoster is caused by a viral infection of the nerves, usually following a cold. It is important to rest, avoid alcohol, and not eat spicy or rich foods. Additionally, take some antiviral medication such as acyclovir orally, and vitamins B1 and B12 to nourish the nerves. Make sure to rest well, avoid staying up late, and refrain from overexertion. For external use, it is best to apply some acyclovir to prevent infection.