Cold sores are small, fluid-filled blisters that develop around the lips or inside the mouth. Cold sores are caused by herpes simplex virus (HSV). HSV infection is passed on through skin-to-skin contact such as kissing.
There are two types of HSV, HSV-1 and HSV-2. Cold sores are mainly caused by HSV-1. HSV-2 can also infect the mouth, although it mainly causes genital herpes.
About eight in 10 people have HSV-1 antibodies – meaning they have the virus. From the first time you get HSV (primary infection), the virus stays in your body for the rest of your life.
The primary infection with HSV can develop in different ways. It may cause mild symptoms or no symptoms at all. Children under five are most likely to be ill from a primary infection. Your child may have:
Blisters will usually appear one to three weeks after getting the virus and last for 10 to 14 days.
As a primary infection in adults, HSV may cause a glandular fever type illness (sore throat and swollen tonsils with fever and headache).
After the primary infection, with or without symptoms, the virus lies dormant in your body but can reactivate and cause blisters on the lips (cold sores).
Recurrent outbreaks usually start with a tingling sensation, redness and swelling around the lip. This is followed by small, fluid-filled blisters, which break open and develop a yellow crust (scab). The scab usually falls off around seven days later.
Recurrent outbreaks usually occur in or around the same place each time. It's possible to have two to three outbreaks a year.
The sores can become infected with bacteria and cause impetigo.
Cold sores can spread to other areas of skin such as the fingers, eyes or genitals. If the virus spreads to the eyes, it can damage vision. If it spreads to the genitals, it can cause genital herpes.
The virus can spread into broken skin (for example, eczema or dermatitis) and cause a serious skin infection.
If you have symptoms of either primary or recurrent HSV infection and you have a weakened immune system (for example, if you have HIV/AIDS or are taking medicines that suppress your immune system), you should visit your GP. There is a risk the virus may cause serious illness.
Although rare in Australia, there is a risk that you can pass HSV infection to your baby in pregnancy, during the birth or immediately after birth. This is known as neonatal herpes and can cause your baby to be seriously ill. This is more of an issue if you have genital herpes. But if you have any symptoms of a primary HSV infection or cold sores for the first time when you are pregnant, particularly in the later stages of pregnancy, you should see your GP or obstetrician for advice.
Cold sores are usually caused by HSV-1 and the infection is passed through skin-to-skin contact such as kissing someone who has the virus or by sharing objects which have been in contact with the virus, such as a razor or a lipstick.
There are several factors that can trigger an episode of cold sores, including:
For many people, however, the trigger is unknown.
Usually, your GP will be able to recognise cold sores (or oral herpes infection) from looking inside and around your mouth. Your doctor may take a swab from the blister and send it to a laboratory to confirm that you have the herpes virus.
There is no treatment that can get rid of the herpes virus from your body. Once you are infected, it will remain in your body, even if you never get any symptoms.
Cold sores usually clear up within a week or so. There are steps that you can take to help relieve any pain or discomfort from cold sores and prevent them spreading.
Always read the consumer medicine information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.
If you or your child has severe blistering of the mouth and gums, the following steps may help ease any pain or discomfort.
There are ways that you can lower your risk of getting or passing on cold sores and preventing recurrent episodes.
Stress and feeling run down can trigger recurrent episodes of cold sores. Taking measures to prevent feeling stressed or run down can also help reduce your risk of having an outbreak.
Australian Herpes Management Forum
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