Skin
Medicines for Cold sores
Small, painful blisters around the lips and mouth caused by the herpes simplex virus, which tend to recur but are usually self-limiting — and respond best to antiviral treatment started at the very first tingle.
Education and reference only. This explains which medicines are used and why, in plain language — it deliberately contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician, and check the BNF and the product labelling for prescribing detail.
Quick answer
What is Cold sores?
Cold sores are small, fluid-filled blisters that appear around the lips and mouth, caused by the herpes simplex virus. Most people catch the virus in childhood, often without knowing, after which it stays dormant in the body and can reactivate from time to time, producing a fresh cold sore.
- How it is treated: The guiding principle is that cold sores generally heal on their own, so treatment aims to ease discomfort, speed healing a little and limit spread.
- Self-care: Avoiding known triggers where possible, using a lip balm with sun protection, not touching or picking the sore, washing hands carefully and not sharing utensils, towels or lip products all help comfort and reduce the risk of spreading the virus.
- When to seek help: See a pharmacist or GP if a cold sore is severe, very painful, unusually large or widespread, lasts longer than about ten days, or keeps coming back frequently.
What it is
Cold sores are small, fluid-filled blisters that appear around the lips and mouth, caused by the herpes simplex virus. Most people catch the virus in childhood, often without knowing, after which it stays dormant in the body and can reactivate from time to time, producing a fresh cold sore. An outbreak often begins with a tingling, itching or burning feeling in one spot — the "prodrome" — before blisters form, weep, crust over and heal, usually within a week to ten days. Common triggers for reactivation include other illnesses such as colds, tiredness, stress, strong sunlight and, in some people, periods. Cold sores are contagious, particularly while blisters are present. They are normally recognised from their appearance and pattern without any tests, and although they can be uncomfortable and recur, in healthy people they are usually a self-limiting nuisance rather than a serious problem.
How it is treated
The guiding principle is that cold sores generally heal on their own, so treatment aims to ease discomfort, speed healing a little and limit spread. Antiviral creams and, for some people, antiviral tablets work best when started at the very first sign — the tingle before blisters appear — and become much less helpful once a sore is well established. Many mild outbreaks need no specific treatment at all beyond simple comfort measures and keeping the area clean. People who get frequent or severe recurrences, or whose outbreaks are reliably triggered by sunlight, may be advised on antiviral tablets or prevention strategies. The other key principle is recognising who needs more careful attention: cold sores that are severe or widespread, those near the eye, and outbreaks in people who are immunocompromised or who have eczema (where the virus can spread dangerously, a condition called eczema herpeticum) all need prompt medical advice rather than self-treatment alone.
For this condition, these medicines
Medicine classes used for Cold sores
Each links to a full, dose-free guide — what it is, how it works, who can and cannot use it, side effects, interactions and FAQs.
Symptom checker
Symptoms that can point to Cold sores
Cold sores can be one cause of these symptoms. Each guide explains the other possible causes and the red-flag warning signs that mean you should get urgent help:
Beyond medication
Lifestyle and self-care
Avoiding known triggers where possible, using a lip balm with sun protection, not touching or picking the sore, washing hands carefully and not sharing utensils, towels or lip products all help comfort and reduce the risk of spreading the virus.
When to get help
When to see a doctor
See a pharmacist or GP if a cold sore is severe, very painful, unusually large or widespread, lasts longer than about ten days, or keeps coming back frequently. Seek prompt medical advice if a cold sore develops near or in the eye, or if outbreaks occur in someone with a weakened immune system. People with eczema need particular care, as the virus can spread across affected skin to cause a serious infection called eczema herpeticum — rapidly spreading sores, with feeling unwell or a fever, need urgent assessment.
Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.
Answers
Cold sores: frequently asked questions
What medicines are used for cold sores?
Cold sores are treated with antiviral medicines that act against the herpes simplex virus. These come as creams for individual outbreaks and, for people with more severe, frequent or troublesome cold sores, as tablets. They work best when started at the very first sign — the tingling or itching before blisters appear — and become much less effective once a sore is fully formed. Many mild cold sores need no specific treatment and heal on their own with simple comfort measures.
When should I start antiviral treatment for the best effect?
As early as possible. Antiviral creams and tablets are most helpful when started at the prodrome — the tingling, itching or burning you may feel in one spot a day or so before the blisters appear. Starting at this point gives the best chance of easing the outbreak and shortening healing. Once blisters have formed and crusted, antivirals make far less difference, so it pays to act at the very first warning sign if you know your triggers.
Are cold sores contagious?
Yes. The herpes simplex virus that causes cold sores spreads through close contact, especially while a sore is present and weeping. To reduce the risk of passing it on or spreading it elsewhere on your own body, avoid touching or picking the sore, wash your hands carefully, do not share items such as cutlery, towels, razors or lip products, and avoid kissing — and oral contact with babies — until the sore has fully healed. Take extra care around anyone with a weakened immune system or eczema.
When should I worry about a cold sore?
Most cold sores are an uncomfortable nuisance that clear up by themselves. Get medical advice, though, if a cold sore is severe, very large or widespread, lasts more than about ten days, or recurs often. A cold sore near or in the eye needs prompt attention, as does any outbreak in someone with a weakened immune system. People with eczema should be especially careful, because the virus can spread across the skin to cause a serious infection called eczema herpeticum, which needs urgent assessment.
Keep reading
Related articles
Sources
Where this is drawn from
- NICE CKS: Herpes simplex — oral.
- NICE CKS: Cold sores.
Related conditions
Browse by body system
Building a patient-information or formulary resource?
We create evidence-led, dose-free clinical references and decision aids for teams.