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A cold sore is usually a recurring blistered lesion on the lips or around the mouth. It is most often caused by HSV-1. During oral sex, this virus can also pass to the genitals. [1]
If your symptoms are in the genital area, it is worth reading our guide to genital herpes.
How can it be recognised?
The blisters are often preceded by tingling, burning or itching. Later, fluid-filled blisters may appear, then a crust. Healing usually starts within about ten days. [3]
When should you ask for medical help?
If it has not started to heal within ten days, if the lesion is unusually large or painful, or if its cause is uncertain, it is worth having it seen. If the immune system is weakened, ask for medical advice as well. [3]
Investigation and treatment
A typical cold sore can often be recognised from the symptoms. If the case is uncertain or unusual, the doctor decides whether a further test is needed. A pharmacist or a doctor may suggest treatment to ease the symptoms. [3]
IMPORTANT INFORMATION FOR PATIENTS
- Is a laboratory test needed every time?
- Not necessarily. Whether a test is needed is best discussed on the basis of the current symptoms.
- Can the cold sore come back?
- Yes, the virus can remain dormant in the body and cause symptoms again later. [1]
- How will I receive my result?
- With your consent, we email your result as an encrypted, password-protected PDF. At the follow-up consultation, our specialist will explain it to you in detail. How results are sent
How can you reduce the chance of passing it on?
From the start of the tingling until it has fully healed, avoid kissing and oral sex. Do not pick the blisters; wash your hands after touching them. If you have a cold sore, do not kiss a baby, because neonatal herpes can cause serious illness. [3]
If symptoms keep coming back, or their cause is uncertain, ask our clinic for personalised advice.
Sources: [1] WHO – herpes simplex virus · [2] NHS – genital herpes · [3] NHS – cold sores
This guide does not replace a consultation with a doctor.