Most people are familiar with cold sores, the small blisters or scabs that develop on the lips. Cold sores are caused by the herpes simplex virus and occur after an outbreak when virus levels build up. Cold sores will often start in the ‘tingle’ phase where there is a tingling, itching or burning sensation in the area before a breakout where the blisters occur. The blisters or sores usually last for around 7 to 10 days and will clear up without treatment. If you start treatment at the tingle stage, you can sometimes prevent the outbreak from happening.

Cold sores are caused by one of the herpes simplex virus family known as HSV-1. In rare cases cold sores can be caused by HSV-2, however, this is normally due to having oral sex with a person who has genital herpes.

Cold sores are highly contagious and are passed on by direct contact, normally through kissing or sharing lipsticks or cutlery. Once you have HSV-1, it lies dormant in the nerves until an outbreak, normally caused by a trigger factor. Some people can get outbreaks every few months whereas others can go for years without a cold sore.

Cold sores occur when levels of the herpes simplex virus build up causing an outbreak of small blisters on the lips. The outbreak of cold sores is usually caused in response to trigger factors that can include:

• A low immune system (possibly due to another infection or illness)
• Fever or high temperature
• Stress or being upset
• Tiredness or fatigue
• Exposure to strong sunlight
• Injury to the mouth or lips
• Menstruation

Although an outbreak normally occurs in response to a trigger factor, cold sores can also occur randomly where there is no obvious trigger.

When you are first infected with HSV-1, it is unlikely you will experience any symptoms during the primary infection and it may be some time before your first outbreak. Symptoms of the primary infection of herpes simplex can be more severe and may include:

• Sore throat
• Swollen glands
• Bad breath (halitosis)
• Painful sores in and around the mouth

After the primary infection, recurrent bouts of herpes simplex outbreaks will normally only cause cold sores without any of the symptoms described above. Cold sores normally follow a regular pattern:

1. ‘Tingle’ Phase: a tingling, itching or burning sensation that acts as a sign that an outbreak is imminent in the area it is experienced.
2. Outbreak: small, fluid-filled sores or blisters develop around the area where the ‘tingle’ phase occurred. The outbreak normally occurs 12 – 48 hours after the ‘tingle’ phase starts. Some of the cold sores may ooze or weep.
3. Healing: the cold sores will stop oozing and start to scab over. They will slowly reduce in size and the irritation will ease. They will normally completely heal in 7 – 10 days.

Cold sores are contagious from the start of an outbreak until they have completely healed. They are most infectious during the outbreak when they have burst and are oozing.

Cold sores can normally be self-diagnosed without the need to see your GP. You should check with your doctor if you experience any of the following:

• You have very frequent or multiple cold sores.
• Your cold sores last longer than 10 days or do not respond to treatment.
• You show any signs of a weakened immune system such as fever or malaise.

If your primary infection is severe you may wish to see your GP for treatment.

Antiviral cream such as Aciclovir 5% cream is the first-line treatment for recurrent outbreaks of cold sores. If used correctly, they can speed up the healing time of cold sores or even prevent the breakout in some cases.

It is important when using cold sore treatment creams, like Aciclovir (Zovirax), that they are applied as soon as possible after the ‘tingle’ phase begins. This gives it the best chance of preventing the outbreak or speeding up the healing time. Once the cold sore has blistered or scabbed, antiviral cream will have less effect.

Antiviral cold sore creams prevent the herpes simplex virus from spreading and multiplying. It is normally applied five times daily for up to nine days. Cold sore treatments help to treat the current outbreak, however, they do not ‘cure’ the herpes simplex infection or prevent future cold sore outbreaks. Antiviral cold sore creams should not be used as a preventative measure to stop outbreaks when there are no signs of one occurring.

General tips for treating cold sores

Ensure you stay hydrated by drinking plenty of fluids. This will stop your lips from becoming dry and cracked.
Try to avoid acidic or salty foods, as this will irritate your cold sore further.
Use an antiseptic mouthwash 2 – 3 times daily if brushing your teeth is too painful.
When applying cold sore cream to the area, dab it on and let it soak in rather than rubbing it in.
Avoid touching the cold sore and surrounding area wherever possible.
If you do touch your cold sore, such as when you are applying cold sore cream, make sure you wash your hands thoroughly using soap and water.
Don’t share your cold sore cream with others.

How to minimise the spread of cold sores

You can’t completely remove the risk of becoming infected with cold sores however there are many steps you can take to reduce the risk of you catching HSV-1 or passing it on to others.

• Avoid touching the cold sore and surrounding area wherever possible.
• If you do touch your cold sore, such as when you are applying cold sore cream, make sure you wash your hands thoroughly using soap and water.
• Don’t share your cold sore cream with others.
• Do not share any other items that may have come into contact with your cold sore or the surrounding area, such as mugs, cutlery or lipsticks.
• Avoid kissing or having oral sex whilst you or your partner has a cold sore. Wait until it has completely healed so they are no longer contagious.
• Be especially careful around those who may have a low immune system such as young babies, pregnant women and those undergoing chemotherapy or who have HIV.

Preventing recurrent outbreaks of cold sores

Outbreaks of cold sores are normally caused by exposure to trigger factors that can be specific to the individual. Examples of the most common trigger factors for cold sores are given above in the ‘What are Cold Sores and what causes them?’ section. By avoiding the trigger factors for your cold sores you can reduce the frequency of cold sore outbreaks.

By applying antiviral cold sore creams, such as Aciclovir 5% cream, as early as possible into the ‘tingle’ phase, you can sometimes prevent breakouts from happening. There is no benefit to using cold sore creams continuously to prevent cold sores.