What causes cold sores?
Cold sores are an uncomfortable and sometimes embarrassing skin condition caused by the herpes simplex virus (HSV). People are usually infected with HSV in childhood or early adulthood and the virus stays in the body for life. Although the word ‘herpes’ may conjure negative stereotypes, exposure to HSV is very common. Around 90% of adults have herpes simplex antibodies present in their bloodstream, which means that they have been exposed to the virus at some time, but only one‐third of infected people will actually experience cold sore outbreaks.1
Cold sores are characterised by small fluid‐filled blisters on the lips or around the mouth and are often accompanied by pain or a burning sensation. They will usually burst, develop a scab and then clear up, all within 10 days without any serious complications.
How is HSV transmitted?
The virus that causes cold sores is usually transmitted through contact with saliva or direct exposure to a blister. Kissing and sharing eating utensils or personal items such as a razor can cause you to contract HSV.2 Once infected, HSV remains dormant in the skin cells of the lips, which means that even people without any symptoms can pass the virus onto others.1
When you first contract HSV, it usually does not cause any symptoms. At this time, the virus makes its way into the sensory nerve endings and finds a permanent home in the nerve cells. There it remains latent until something triggers its replication. Virus particles are made, which travel to the skin surface, resulting in the telltale blisters.3 In time the blister heals and the virus remains dormant again until another potential outbreak.
What triggers cold sore outbreaks?
In many people, cold sores tend to pop up at the most inopportune times e.g. when you have an important meeting or big event. This is because emotional stress, which often accompanies these events, can reactivate the dormant virus and cause the symptoms of a cold sore.1 Other factors that can trigger a cold sore outbreak include:1
- Exposure to sunlight.
- Illness such as the common cold or flu.
- Windy conditions.
- Hormonal changes such as menstruation.
- Physical stress.
Sometimes, cold sores may form without an identifiable trigger.
Who is at risk of cold sores?
The virus that causes cold sores is very prevalent and easily spread, which means that virtually everyone is at risk of contracting it. The majority of children between the ages of six months to three years of age are exposed to HSV through close contact with other people. In adulthood, up to about 90% of men and women will have been infected with the virus.1 Infection doesn’t mean you will always develop blisters. This is dependent on individual trigger events, for example how stressed you may be. Some people may never experience any active symptoms or visible blisters.