Primary cold sore infection

What is a primary cold sore infection?

Cold sores are caused by the herpes simplex virus (HSV). The first time you are infected with this virus is called the primary infection. The mouth is the area most commonly affected. This is because normal skin is resistant to the virus but the moist inner skin of the mouth is not. The first (primary) infection is often in childhood. It is often caught by kisses from a family member who has a cold sore.

The primary cold sore infection can be worse than recurrent cold sores but some people don't experience any symptoms at all. It tends to fall at either end of the spectrum (significant symptoms or no symptoms).

This leaflet will deal with primary cold sore infection. See the separate leaflet called Cold sores for more details on recurrent cold sores.

What are the symptoms of a primary cold sore infection?

Symptoms of the first (primary) infection are often different to recurring cold sores.

• No symptoms. You may have no symptoms, or only trivial ones. For example, you may not realise that a tiny spot on the tongue is a first cold sore. However, you may then develop typical cold sores from time to time in the future.

• Blisters. You may have a more severe infection in and around the mouth. Small blisters or ulcers may develop on the mouth, tongue, gums, lips, or throat. This is called gingivostomatitis. There may be only a few blisters but sometimes there are lots.

• Pain. The blisters and ulcers are often painful. Swallowing or eating may become quite painful. The pain may cause saliva to pool in your mouth and children may drool (dribble).

• Glands. The glands in your neck may swell and become tender.

• Fever. You may develop a high temperature (fever) and general aches and pains.

The infection gradually subsides and goes within 1-3 weeks.

What are the treatments for a primary cold sore infection?

• Painkillers such as paracetamol or ibuprofen can ease the pain for primary cold sore infection.

• Benzydamine mouthwash or spray may be useful in relieving the pain from a sore ulcerated mouth.

• Choline salicylate gel (Bonjela dental gel) can be used in the mouth to reduce pain. Bonjela should not be used in children under the age of 16, due to a potential risk of Reye's syndrome. This is the same reason why aspirin cannot be used in children too. Note: Bonjela teething gel no longer contains choline salicylate and has been reformulated with lidocaine, a local anaesthetic (to cause temporary numbing). This means that Bonjela teething gel® can be used in children.

• Keep hydrated. Have plenty to drink. It may be painful to drink but it is important to drink to prevent dehydration.

• Mouthwash. If it is too painful to clean your teeth, chlorhexidine mouthwash (brand name Corsodyl® or Chlorohex®) can be used in place of brushing. It may help adults or children old enough to use it to keep the mouth and teeth clean, to prevent plaque build-up and secondary infection with germs (bacteria).

• Soft foods such as yoghurts and soups are easier to eat when your mouth is painful. Cold or cool foods may be less painful than hot foods.

• An antiviral medicine (such as aciclovir) is sometimes prescribed if the symptoms are severe or if you have an existing medical condition which means that your immune system does not work properly. It is taken by mouth, rather than the topical creams used to rub on cold sores. It does not clear the virus but prevents the virus from multiplying. It may not have much effect once the blisters and ulcers are well developed. However, if taken early in the infection, it may reduce the duration of the pain and speed recovery a little.

• Lip barrier preparations such as Vaseline or Lypsyl may make the lips feel more comfortable and may stop them from sticking or scabbing together.

General measures include trying to reduce the chances of passing the cold sore virus on to others. It is very important to wash your hands carefully with soap and water after touching the mouth and cold sores. You should avoid touching cold sores or ulcers in the mouth associated with first (primary) infection, except when applying medication. You should not have oral sex when you have either a primary cold sore infection or an individual cold sore. Finally, it is important not to share items that come into contact with infected areas - this would include lipsticks and lip balms and eating utensils.

Children

Young children may be distressed with the pain and refuse to take medicine or drinks. Tips to help include:

• Try using a syringe (which you can buy at pharmacies) to squirt medicine into the side of the mouth slowly. Do not squirt into the back of the mouth.

• Keep offering cool drinks. You can also use a syringe to give some drinks. Again, slowly squirt into the side of the mouth, not towards the back of the mouth.

• Sucking ice pops or ice cubes may help to ease the pain and are also a way of giving fluids.

Occasionally, a child stops drinking because of the pain in their mouth. They are then in danger of becoming dehydrated. If your child has significantly reduced urine, or if their urine is dark in colour and strong-smelling, they are likely to be dehydrated. Seek medical advice if you are concerned that your child is not drinking enough and is becoming dehydrated. Some children who are at risk of dehydration are admitted to hospital for a short while until the infection settles and they are drinking normally again. In hospital they can have their fluid intake monitored and they can be given an intravenous drip if needed.

If your child is generally well with a primary herpes virus infection, they do not need to be kept off school or nursery.

When should I consult a doctor for a primary cold sore infection?

You should seek medical advice at any time if you are particularly worried about yourself or your child. This may be the case if you have a weakened immune system (immunocompromised). Immunocompromised people include those with conditions such as AIDS, or those receiving chemotherapy or other medicines which lower the body's resistance to infections. Pregnant women should also seek prompt medical attention. Very young children and babies with a primary cold sore infection should also seek medical help. Anyone with a primary cold sore infection where the symptoms are not settling after ten days, should see their GP.

Recurrent cold sores

After a first (primary) infection has cleared, the virus remains dormant (inactive) in a nerve sheath. Most of the time this causes no problems. In some people the virus 'activates' from time to time to cause cold sores around the mouth and nose. Repeated (recurrent) cold sores may be unpleasant but do not usually cause severe mouth infections like some primary infections. About 1 in 5 people in the UK have recurrent cold sores.