Cold sore infections
What are cold sores?
Cold sores are lesions caused by a virus infection that usually occur on or around the lip, or nose. They are often preceded by a feeling of tingling, burning, itching, or numbness in the spot where the cold sore is developing. As the cold sore becomes visible, small red spots and fluid blisters appear. These usually merge together into what looks like one sore. Unless there is a secondary infection, cold sores usually clear up within 10 days, and do not leave a scar.
Cold sores are caused by the herpes simplex virus. This is different from the 'shingles' or zoster herpes virus.
There are two types of herpes simplex virus: type 1 and type 2. Most cold sores are caused by herpes simplex virus type 1. However, both type 1 and type 2 virus can cause sores in the genital area. Cold sores are contagious, so infection can be passed by direct contact such as kissing and oral sex.
The virus remains in the body and can cause cold sores to recur if you are stressed, tired, feverish or injured (including after surgery). Exposure to sun or wind can also trigger an outbreak of cold sores, so you should use sunscreen to help prevent the virus from being reactivated.
Helpful tips about cold sores
If you have a cold sore you should:
- keep it moist with an ointment, avoiding dry cracked areas;
- avoid using astringents on the cold sore;
- treat symptomatically with an oral analgesic and topical anaesthetic drugs (e.g. lignocaine gel every 3 hours);
- avoid passing the virus on through kissing or oral sex, or through sharing eating utensils, razors or towels;
- wash your hands before touching another person;
- make sure you do not touch other parts of your body, especially your eyes and genital area, if you have touched the cold sore; and
- have antiviral treatment ready, either a cream available over-the-counter or an oral tablet that you can obtain on prescription, so you can use it at the first tingle.
When should you seek medical advice about cold sores?
See your doctor or pharmacist if:
- you have cold sore symptoms and your immune system is weak (e.g. you have HIV, cancer or an organ transplant);
- your cold sore covers a large area (as big as a 10 cent piece);
- you have more than one cold sore;
- your cold sore is crusty and has pus, as this is a sign of a secondary infection;
- your cold sore has spread near your eyes or your eyes are irritated;
- a young child has cold sores;
- you have persistent or frequently recurring cold sores;
- you know the trigger for recurrences and you expect to be exposed to that trigger; or
- the sores are painless, without the early itch or tingle, as these may be skin cancers.
Last Reviewed: 07 July 2010
- 1. Australian Herpes Management Forum. Guidelines for clinicians: managing oral herpes. Sydney: Australian Herpes Management Forum, 2009. http://www.ahmf.com.au/guidelines/oral-herpes/managing-oral-herpes (accessed 15 Nov 2010).
2. Oral mucocutaneous herpes simplex. In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2009. http://online.tg.org.au/complete/ (accessed 15 Nov 2010).
3. Haddow LJ, Dave B, Mindel A, et al. Increase in rates of herpes simplex virus type 1 as a cause of anogenital herpes in western Sydney, Australia, between 1979 and 2003. Sex Transm Infect 2006; 82: 255-9. doi: 10.1136/sti.2005.018176. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2564751 (accessed 15 Nov 2010).
4. Mayo Clinic. Cold sore. March 2010. http://www.mayoclinic.com/health/cold-sore/DS00358 (accessed 15 Nov 2010).
