Cold sore

Cold sores are most often caused by the herpes simplex virus type 1 (HSV-1), and in most people the infection actually happens way back in early childhood. Often it spreads when a child is kissed by a relative or family friend who has a cold sore at the time.

Once the virus gets into the skin, it travels up along the nerves and settles there quietly. It can stay inactive like this for a long time, only becoming active again when something triggers it later on.

Common cold sore triggers

An outbreak can be set off by things like:

• another infection, such as a respiratory tract infection
• a high temperature or fever
• emotional upset or psychological stress
• tiredness and fatigue
• an injury to the affected area
• menstruation (periods)
• strong sunlight

That said, quite often there is no clear trigger at all, and an outbreak can simply appear on its own.

Herpes simplex virus type 2

In some cases, cold sores are caused by herpes simplex virus type 2 (HSV-2) instead. This usually happens after oral sex with a partner who has genital herpes, since HSV-2 is the virus most often responsible for that condition.

With genital herpes, the person develops painful blisters on the genitals and the area around them.

Treatment for a cold sore

Things you can do

Do

• eat cool, soft foods
• wash your hands with soap and water before and after applying cream
• avoid anything that triggers your cold sores
• use sunblock lip balm (SPF 15 or above) if you’re outside in the sun
• use an antiseptic mouthwash if brushing your teeth is painful
• take paracetamol or ibuprofen to ease pain and swelling (both come in liquid form for young children) – do not give aspirin to children under 16
• drink plenty of fluids to avoid dehydration

Don’t

• do not kiss anyone while you have a cold sore
• do not have oral sex until your cold sore completely heals
• do not touch your cold sore (apart from applying cream) – if you do, wash your hands
• do not rub cream into the cold sore – dab it on instead
• do not eat acidic or salty foods if they make your cold sore feel worse

Treatment from a pharmacist

If you get cold sores, a pharmacist may recommend:

• creams to ease pain and irritation
• antiviral creams to speed up the healing time
• cold sore patches to protect the skin while it heals

You can buy electronic devices from pharmacies that treat cold sores with light or lasers. Some people find these helpful, but there have not been many studies to confirm if they work.

If you regularly get cold sores, use antiviral creams as soon as you recognise the early tingling feeling. They do not always work after blisters appear.

Treatment from a GP

If your cold sores are very large, painful and keep coming back, your GP may prescribe antiviral tablets.

Newborn babies, pregnant women and people with a weakened immune system who have cold sores may be referred to hospital for advice or treatment.

There's no way to fully prevent getting the herpes simplex virus or stop cold sore outbreaks from happening. Even so, you can take a few steps to keep from passing the infection on to others.

Cold sores spread most easily once they burst open, but they stay contagious right up until they've healed completely and disappeared. It's best to avoid close contact with others during this time, until your cold sore is fully healed.

That said, you don't need to stay home from work, and your child doesn't need to miss school, just because of a cold sore.

Cold sores are usually mild, and serious problems are rare. People whose immune system is weakened by illness or by treatments such as chemotherapy do face a higher risk of complications.

Dehydration can sometimes set in if swallowing fluids becomes too painful. Young children are especially at risk of becoming dehydrated for this reason.

Other complications linked to cold sores include:

• skin infections, which often occur when the virus spreads to broken skin, such as a cut, a graze, or an area affected by a skin condition like eczema
• herpetic whitlow, also called whitlow finger, which causes painful sores and blisters to form on and around the fingers
• herpetic keratoconjunctivitis, which causes swelling and irritation around the eye, along with sores developing on the eyelids