Pharmacy Corner
Cold Sores: What You Need to Know What is a cold sore?

A cold sore is a common skin infection. It causes a small group of blisters to appear around the lip and mouth area. These blisters may break open, leak fluid and crust over. They usually last for up to 2 weeks before healing completely.


Cold sores and fever blisters are exactly the same thing.

What causes cold sores?

Cold sores are caused by a virus called herpes simplex virus (HSV). HSV comes in two forms: HSV-1 and HSV-2. Either type can cause cold sores but HSV-1 does so most often. There are also two types of infection, the first infection and recurrent (repeat) infections.

First (primary) infection

The first outbreak of a cold sore happens when the virus enters your body for the first time. It is usually more severe and lasts 1-3 weeks. The first infection starts with fever, fatigue, difficulty swallowing and swollen lymph nodes in the neck. Painful cold sores may involve the entire lining of the mouth and both lips. It is common for some people to never have symptoms of a first infection.


About 60-95% of adults are infected with the cold sore virus5. It is a very common condition.

Why do I keep getting them?

Recurrent infections

Once the first infection clears up, the virus stays in the body and may cause cold sores to return throughout your lifetime. This is because when the virus is not active on the surface of the skin it remains in a sleeping state inside your cells until a trigger reactivates it causing the cold sore to come back. Some people don’t suffer any recurrences whereas others can have 10 or more per year.

Recurrent infections are usually less severe than primary infections. They don’t last as long, sores are smaller and don’t normally cause other symptoms like fever or fatigue.

Do I need treatment? What’s the prognosis?

Cold sores will go away without treatment after 7-14 days. Unfortunately there is no way to cure the infection. Both prescription and non-prescription treatments help with the symptoms, decrease cold sore severity and help shorten the time you have them.