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Acyclovir cream

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 2 minutes read

Acyclovir cream 5% is an antiviral cream used to treat cold sores on the face and lips. It is best applied at the early stages of a cold sore outbreak where it helps to prevent a cold sore from fully developing. It may also be used to treat and speed up healing of a cold sore that has already developed. In the US, acyclovir requires a prescription.

Doctor’s advice

Who is it for?

Acyclovir cream can be used in both children and adults who have a cold sore. You may have had them before, therefore you can recognize the tingling or burning sensation and apply it then, or it may be the first time you’ve had a cold sore. Cold sores are an infection caused by the herpes simplex virus – once you’ve had contact with the virus, it lies dormant in the skin and may flare up from time to time. You might recognize triggers – stress and exposure to the cold or sun are common ones. Unfortunately, acyclovir only treats the symptoms of a cold sore, nothing can cure you of the virus or prevent any future cold sores.

How do I apply it?

Acyclovir is an antiviral agent that interferes with the growth and replication of viral particles, helping your immune system to target and tackle the virus. Treatment with acyclovir cream is best started at the early stages of a cold sore outbreak; this is identified by a tingling, itching or burning sensation around the lips.

If you've had cold sores before, this is usually in the same area as previous cold sores. Acyclovir cream may also be applied to a fully developed cold sore, when a blister or crust appears. Applied at this stage, acyclovir helps the cold sore heal faster and relieve discomfort.

It should be applied to the affected area five times a day, for at least four days. It may be used up to a maximum of 10 days. If the cold sore has not fully healed, or you have a cluster of many, or you’re getting them often, do book an appointment to see your doctor.

Is it for everyone?

Acyclovir cream should not be used by people who are immunocompromised, where you have an immune system weakened by a medical condition or medication. It should not be used if you have allergies to acyclovir or any of the ingredients listed. You should avoid applying to the eye or inside of the mouth. It should not be used for more than 10 days.

Are there any side effects?

Cold sores are common and acyclovir cream is well-tolerated in most. Some ingredients in acyclovir cream may cause sensitivity or irritation in some people. Symptoms indicating this include burning or stinging, and redness or dryness of the skin. If this happens, stop using the cream and seek medical advice.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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