General Information

Cold sores are caused by the herpes simplex type 1 virus. Most people carry this virus in their bodies, but not everyone will get cold sores.

People usually become infected with the virus during childhood. After a usually mild (or unnoticed) infection, the virus then lies dormant (inactive) in the nerves until it is reactivated and causes a cold sore.

Cold sores are usually found on or around the lips or nose, but they may occur anywhere on the body. They often appear in the same place each time.

Cold sores are easily spread from person to person, especially when the sore is still weeping. They can be spread by kissing and sharing towels.

Common triggers that can cause the virus to reactivate include:

  • having a cold or the flu
  • exposure to bright sunlight
  • emotional stress or being ‘run down’ or unwell
  • menstruation
  • operations on the face or dental work
  • minor damage or injury to an area affected by cold sores in the past

When the virus is reactivated it travels down the nerve to your skin, where it multiplies. This often causes a tingling feeling in the area, which can be a warning sign a cold sore is about to appear. Other warning signs may include burning, itching or numbness. These signs may appear within a few hours to a couple of days before the blisters develop.

As the virus multiplies it causes small red spots, before the blisters appear. The blisters then burst and merge into a weeping sore, which gradually dries up and scabs over. Cold sores usually clear up within seven to 10 days and do not usually leave a scar. After the sore has healed, the virus lies dormant in the nerve again until the next attack is triggered. Recurrence can be common and depends on individual trigger factors.

Cold sores are usually mild and clear up without treatment. They can sometimes become infected with bacteria, especially if you touch or pick them with your hands. However, they can cause more serious problems in someone with a weakened immune system, such as after chemotherapy or due to HIV infection. These people may need treatment with antiviral tablets.

Very rarely, facial cold sores are caused by the herpes simplex type 2 virus, which is responsible for genital herpes.

See Your Pharmacist or Medical Professional

  • if the cold sore is in or near your eyes
  • if the cold sore is in your mouth, on your hands or in your genital area
  • if the cold sore is larger than a 10 cent piece
  • if you also have a fever and feel tired
  • if it is a child who is affected. Cold sores are not commonly seen in children, and it may be another condition such as impetigo
  • if there is pus, redness and swelling in or around the cold sore
  • if the cold sore has not healed after 14 days
  • if you suffer from cold sores frequently
  • if you have a weakened immune system

Treatment Tips

  • treat the cold sore early; have treatment ready to use at the first tingle
  • use sunscreen on the affected area if you find the virus is reactivated by sun exposure
  • wash your hands before and after touching the cold sore, or applying cream to it
  • be especially careful to avoid spreading the cold sore to your eyes
  • avoid kissing or sharing towels, face flannels or eating and drinking utensils
  • do not share your cold sore cream with other people
  • do not pick the scab off; this may cause infection or scarring
  • if you are pregnant or breastfeeding not all products will be suitable; check with your pharmacist

Treatment Options

Antiviral products

e.g. aciclovir (Blistex Antiviral Cold Sore Cream (New Formulation), Nyal Antiviral Cold Sore Cream, Zovirax Cold Sore Cream), povidone iodine (Betadine Cold Sore Ointment and Betadine Cold Sore Paint Pain Relief Formula (Lotion)), idoxuridine + lignocaine + benzalkonium chloride (Virasolve)

  • aciclovir-containing products are effective treatments for cold sores
  • they are proven to help speed healing and can prevent the cold sore from appearing if they are applied early enough
  • they should be used as soon as the first signs of a cold sore are noticed, such as a tingling sensation
  • they can be used at any stage to reduce healing time; see individual products for further details
  • products containing povidone iodine or idoxuridine may help treat cold sores but they are not as effective as aciclovir
  • products containing povidone iodine or benzalkonium chloride may help reduce the chances of a cold sore becoming infected with bacteria
  • if the cold sore is fully developed, products containing a local anaesthetic, such as lignocaine (Virasolve), can help relieve pain

Pain relief products

e.g. menthol and camphor (Nyal Cold Sore Cream)

  • products containing menthol and camphor can help reduce discomfort, but some people find that they irritate their skin

More Information

Availability of medicines

  • GENERAL SALE available through pharmacies and possibly other retail outlets.
  • PHARMACY ONLY available for sale through pharmacies only.
  • PHARMACIST ONLY may only be sold by a pharmacist.

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Last Reviewed: 26/04/2009