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Cold sore

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 3 minutes read

A cold sore is a small blister on the face that is caused by the herpes simplex virus (HSV). The blister pops and then gets a crust over it. Some people experience tingling or burning before the blister appears, and it can be painful.

They are very common, with many people suffering from repeated cold sores. They usually heal by themselves between 7 and 10 days. Most people are infected with the virus when they are young but may not get a cold sore until many years later. Once infected, the virus stays within you and can be reactivated and cause other cold sores at future points. This is usually around times of stress, tiredness, menstruation, illness, or some people find the sun can cause outbreaks.

Genital herpes and cold sores are caused by the same virus, although there are two different strains (HSV1 and HSV2). It's not really important which one is causing trouble, as treatment is based on symptoms. If you have symptoms in your genital area, see your doctor or a sexual health doctor to discuss this.

Doctor’s advice

Is it contagious?

Cold sores are contagious and can be passed on through direct contact or from items that have touched the cold sore. This is why it is important to avoid kissing anyone, touching your cold sore, or sharing any glasses, cutlery, or anything else that will have come into contact with the cold sore. It’s important to be especially careful around babies or anyone with a compromised immune system, as it can become a serious condition in this group of people.

Healthwords pharmacists' top tips

Cold sores are usually self-limiting and usually heal without treatment within a week. It's very important to avoid touching the cold sore unless dabbing on a cream or gel purchased from your pharmacist and wash your hands thoroughly after touching the area.

If you have suffered from a cold sore before, it's important to stop a new one in its tracks, so ensure you have an antiviral cream in the bathroom cabinet. The moment you notice a cold sore or if you have a tingling or burning sensation, start using the cream.

Antiviral creams effectively reduce the overall size and spread of the blister and can reduce the healing time of the blister. If applied early on, an antiviral cream such as docosanol (Abreva), which can be bought from any pharmacy, helps prevent the cold sore from developing or worsening. Starting an antiviral cream once the blister has already erupted is unlikely to improve the outcome. Still, it's worth simply moisturizing the lips and providing a barrier over the skin to aid healing.

Use as recommended in the instructions, and make sure you wash your hands thoroughly before and after applying the cream. Dab the cream on instead of rubbing it in.

If you feel self-conscious or you have a particular event or meeting, something like the Compeed cold sore patch can be used as a cosmetic cover. It can also provide a protective moisturizing barrier and reduce the drying and cracking of the cold sore.

You can also use a pain-relieving or soothing gel recommended by your pharmacist or pain-relief medications such as acetaminophen and ibuprofen.

When should I see my doctor?

If you have a lowered immune system, either due to a medical condition or medical treatment, book an appointment with your doctor as soon as you notice a cold sore.

Similarly, book an appointment to see your doctor if the cold sore is large or extremely painful, if there are multiple sores clustered together, if you have sores in your mouth or painful gums, or if the cold sore has not healed after 10 days.

The doctor will ask you about your medical history, examine the area, and may prescribe oral or topical antivirals. If you are pregnant or have a lowered immune system, the doctor may refer you to a specialist.

Am I fit for work?

You are fit for work if you have a cold sore.

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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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