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Several viral diseases can cause mouth blisters in children. A single blister does not necessarily cause too much trouble. But diseases with blisters throughout the mouth and throat can hurt immensely, and force the child to refuse food or fluids.
There are, above all, three different diseases that show plenty of oral blisters in children: chickenpox, herpes virus and hand food and mouth disease. All three diseases can also cause fever, but differ in where the blisters sit.
Chickenpox presents as itchy blisters all over the body, and sometimes also in the mouth. In the mouth it can be both itchy and painful.
You can read more about chickenpox here.
Herpes virus (cold sores)
Herpes virus that causes cold sores is found in about 80% of all adults. It is the virus that causes centimetre-sized cold sores that reoccur and hurt in the same place every time. But many people who have the virus in their body never get cold sores. The reason the cold sore comes back is that the body does not manage to get rid of it, but that the virus lies dormant most of the time. Sometimes it comes out and activates and then becomes a cold sore. You are contagious when you have the cold sores and just before (when it starts to tingle), but not otherwise.
The first time you get herpes virus infection, it often settles in the entire oral mucosa. As a rule, it hurts very much, and it is sad to see children have herpes stomatitis, as it is called. The infection lasts for a few weeks, so medical help is often needed with pain relief and sometimes assistance getting fluids and food into the child during that time.
If you have herpes cold sores, try not to infect your child. A kissing ban is essential until the wound heals.
Hand, foot and mouth disease
Hand, food and mouth disease are caused by cocksackievirus and, in addition to blisters in the mouth, also cause blisters or dark red rashes on the hands and feet. The different strains of the hand, foot and mouth virus vary slightly and some can be really troublesome. Most, however, are quite mild.
Read more about hand, foot and mouth disease.
Impetigo is a bacterial infection of the skin. It does not present as blisters, but presents as inflamed, crusty sores on the skin with a red border.
Read more about impetigo here.
Pain relief in the mouth
The big problem with oral blisters is the pain. The pain can often make it difficult for children to take in fluids. As always when children are sick, fluid intake takes priority, while food can wait.
You often need to provide pain relief for the baby. Start by giving acetaminophen at full dose. If it’s not enough, combine with ibuprofen. Ibuprofen is not recommended unless necessary, but if it’s severe pain in the mouth, then it’s necessary
Read more about acetaminophen and ibuprofen for children
Cold therapy can also relieve pain. So bite rings from the freezer and large packs of popsicles can help.
If the child does not drink
If the child does not take in fluids after all of this, then seek the children’s emergency room. The child should drink so that they urinate at least almost normally and so they are reasonably alert. In the children’s emergency room your child may be given local numbing gel in mouth (quite hard, and important to dose correctly). Then, the child may be given a probe (thin soft silicone tube through the nose and into the stomach) or drip tube to provide food while it’s not possible for them to drink.
Chickenpox in children – infection, patterns, incubation period
Hand, foot and mouth disease – blisters in children
Impetigo in childhood infection and treatment
Acetaminophen and Ibuprofen in children – dosage for pain and fever
Red spots and rashes in children – a visual guide