Cold sores
Blisters on the lip caused by a common virus — different from mouth ulcers.
Overview
Cold sores are small blisters, usually on or around the lips, caused by the herpes simplex virus. Most adults carry the virus; sores tend to reappear at the same spot when you are run-down, sunburnt, stressed or unwell, often starting with a tingle before the blisters show.
They are different from mouth ulcers: ulcers sit inside the mouth and are not contagious, while cold sores sit outside on the lip and are very contagious from the first tingle until fully scabbed and healed. Antiviral creams work best if started at the tingle stage; tablets can help people who get frequent or severe outbreaks.
If you have an active cold sore, please tell us before a dental appointment — stretching the lip during treatment can aggravate it and risks spreading the virus, so non-urgent care is usually best rescheduled until it has healed.
What to know
- Caused by a very common virus most adults already carry
- Tingling usually comes before the blisters — that is the time to treat
- Contagious from first tingle until the scab has fully healed
- Different from mouth ulcers, which occur inside the mouth
- Tell us if you have one before an appointment — we may reschedule
Call your dentist if…
- a sore spreads near your eye, you are immunocompromised and develop a cold sore, an outbreak is unusually large or painful, or a lip sore has not healed after two weeks.
