Cold sores

Cold sores are small, painful blisters on or around the lips caused by the herpes simplex virus, most often HSV-1. After the first infection, the virus stays in nerve cells and can become active again. Stress, illness, and sun exposure can trigger outbreaks, though triggers differ from person to person.

Cold sores often start with tingling, itching, or burning, followed by a group of small blisters near the lip edge. The blisters may break open and form a crust. Canker sores usually occur inside the mouth and are not caused by herpes. A physician can assess symptoms that are unclear.

Valacyclovir is an antiviral medicine that slows the herpes virus from making more copies. Taken early, it may shorten a cold sore outbreak. Results vary. It does not cure herpes or remove the virus from your body. A licensed physician in your state decides whether it is appropriate for you.

Start prescribed cold sore medicine at the first tingling, itching, or burning, as directed by your physician. Early treatment may shorten an outbreak. Results vary. Do not wait for a large blister if your prescription says to begin at the first warning sign, and do not take extra doses.

Yes. You can still spread the herpes virus while taking medicine for cold sores. Avoid kissing and oral sex from the first tingling until the skin has fully healed. The virus can also spread when no sore is visible, so treatment does not make close contact risk-free.

Valacyclovir can cause headache, nausea, or stomach discomfort. Less common but serious problems include kidney injury, confusion, and severe allergic reactions. Tell your physician about kidney disease and all medicines you take. Get urgent help for trouble breathing, a severe rash, confusion, or a major drop in urination.

People with kidney disease, a weakened immune system, or a past allergy to antiviral medicine need extra review before cold sore treatment. Pregnancy, breastfeeding, and other medicines also matter. A licensed physician in your state decides whether treatment is appropriate and whether you need a different dose or in-person care.

A cool, damp cloth and a thin layer of plain petroleum jelly may ease cold sore discomfort and protect cracked skin. Results vary. Avoid picking the sore or using harsh products. Ask a pharmacist about pain relief that is safe for you, and wash your hands before and after care.

Some people may have fewer cold sore outbreaks by managing triggers or using prescribed daily antiviral treatment. Results vary. Neither approach removes the virus or guarantees prevention. Keep a record of outbreaks and discuss their frequency, pain, and effect on daily life with a licensed physician in your state.

Get urgent care if cold sore symptoms involve your eye, including eye pain, redness, light sensitivity, or blurred vision. Widespread blisters, trouble drinking, or severe symptoms with a weakened immune system also need prompt care. A sore that has not healed within about two weeks should be checked.