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Cold sores

9-minute read

Key facts

  • Cold sores are small blisters, usually near the mouth.
  • Cold sores are caused by the herpes simplex virus.
  • Cold sores should heal on their own within 2 weeks.
  • You can't cure cold sores, but medicines can help ease the symptoms.
  • Cold sores don't cause complications in most people, but newborn babies and people with weakened immune systems have a higher risk.

What are cold sores?

Cold sores, sometimes referred to as 'oral herpes', are small blister-like spots that appear in or around the mouth. They are caused by infection with the herpes simplex virus. There is no cure for cold sores, but there are ways to treat the symptoms and prevent new outbreaks.

Cold sores commonly appear on or next to the lips. Sometimes, cold sores can appear on the nose, chin or inside the mouth.

Cold sores usually clear up on their own after 2 weeks without leaving any scars. They are highly contagious, even when the blisters aren't present.

The virus can spread between people by direct physical contact with someone who has a cold sore or contact with their bodily fluids, for example, from:

  • kissing
  • skin-to-skin contact
  • sharing drink containers, eating utensils, towels or toothbrushes

What are the symptoms of cold sores?

Cold sores start with an itchy and tingling feeling. They then form small, painful, fluid-filled blisters. Cold sores usually crust over and heal within a few days.

Example of a cold sore around the outside of the mouth.
Example of a cold sore around the outside of the mouth.

As well as a blister-like spot, you may also notice the following symptoms:

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes cold sores?

Cold sores are caused by a virus called herpes simplex.

There are 2 types of herpes simplex virus. Cold sores are usually caused by the herpes simplex virus type 1 (HSV-1). Herpes simplex virus type 2 (HSV-2) causes most cases of genital herpes. However, both viruses can cause both cold sores and/or genital herpes.

HSV-1 is common in the general community, and about 8 in 10 people become infected with HSV-1 by the time they reach adulthood. Most people are infected when they are young, carry the infection for life. The virus can stay dormant (inactive) in many people, meaning that cold sores may never appear. You might have the virus without knowing you're infected.

Various factors can cause the virus to become active resulting in one or more cold sores.

They can include:

When should I see my doctor?

You may need to see a doctor if you have severe symptoms (such as a large, deep or painful sore) or a weakened immune system (for example, if you have HIV or you are having cancer treatment).

It's also a good idea to see your doctor if:

  • there are signs the cold sore is infected, such as redness around the sore, pus and/or a fever
  • the cold sore isn't healing, it's spreading or you have more than one cold sore
  • your cold sore has spread to near your eyes
  • you get cold sores often

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How are cold sores treated?

Cold sores can't be cured but there are many treatments that can help relieve your symptoms. You can ask a pharmacist, doctor or nurse for advice on different treatments.


Antiviral creams or ointments such as aciclovir, famciclovir and valaciclovir can be used in the first few days of a cold sore outbreak, when you first notice a tingling sensation or a raised sore or blister. These are available without prescription from pharmacies and some other shops and supermarkets.

A single dose of antiviral tablets is also available from your pharmacist without a prescription. Talk to your pharmacist to see if they are right for you.

Your pharmacist may also recommend products such as cold sore patches, or creams to reduce symptoms and antiseptic ointments such as povidone-iodine.

If you are in pain, paracetamol may be helpful. You can also get advice from your doctor on pain medicines you can take.

Complementary medicines

Some complementary medicines have been promoted as preventing cold sores. One of these products is an amino acid called lysine — but there is no evidence that it is effective.


There are several things you can do to help your cold sore such as:

  • follow directions on the package of cold sore medicines
  • gently dab creams on to the cold sore rather than rubbing
  • use ice to sooth the pain
  • try not to lick, poke or pick at the area
  • maintain a healthy diet
  • get enough sleep
  • learn and use relaxation techniques to reduce stress

Can cold sores be prevented?

There are steps you can take to prevent spreading cold sores to others if you have them:

  • Avoid any direct physical contact with other people, particularly kissing or sexual activities such as oral sex.
  • Always wash your hands after touching your cold sore.
  • Don't share things such as cups, cutlery, towels, toothbrushes, razors, flannels and cold sore creams with anyone else.

There are also ways to prevent spreading cold sores from erupting again:

  • Minimise or avoid your triggers if you can. Triggers are different for different people, but can include:
    • illnesses
    • sunburn
    • very windy conditions
    • emotional or physical stress
    • hormonal changes — speak with your doctor about what you can do if you notice your menstrual cycle triggers your cold sores
  • Take care of your general health — avoid becoming run down and overly stressed.

Complications of cold sores

For most people, cold sores get better in time with over-the-counter treatments and self-care. However, for people with weakened immune systems, cold sores can be more severe and spread more widely. Infection in a newborn baby should be managed by a doctor.

Babies, children, pregnant people and people with weak immune systems should take extra care to avoid catching the virus that causes cold sores, as it can cause severe illness for these people.

Sometimes the virus that causes cold sores can spread to the eyes, hands or brain — see your doctor immediately if you have cold sores near or close to your eye, as this can lead to severe complications.

Resources and support

For more information, speak with your doctor or local pharmacist — they can help you manage your cold sores and help prevent spread among your close contacts.

The Pharmaceutical Society of Australia has helpful information on cold sores.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

You can also contact the NSW Sexual Health Infoline for free on 1800 451 624 about herpes support groups.

Find more information about sexually transmissible infections for Aboriginal and/or Torres Islander people at Better to Know.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2023

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