any child below 3 months of age who has a temperature of 100. 4 f (38 c) or greater should be seen by a physician or other health-care worker. if a child or adult has a history or diagnosis of cancer aids or other serious illness such as heart disease diabetes or is taking immunosuppressant drugs medical care should be sought for a fever. otherwise observe the person with the fever. if they appear sick or have symptoms that would suggest a major illness such as meningitis (headache stiff neck confusion problems staying awake) urinary tract infection (shaking chills burning with urination) pneumonia (shortness of breath cough) or any other signs of a serious illness contact your health-care provider. other symptoms that may be indicative of a severe illness include repeated vomiting severe diarrhea or skin rashes (could be a sign of dengue fever rocky mountain spotted fever scarlet fever rheumatic fever or chickenpox). fever blisters (herpangina) are small blisters that turn into ulcers usually on the lips mouth or tongue that are caused by a virus. when a child contracts this virus for the first time the symptoms and the fever blisters can be quite severe. if the child is not eating or drinking contact your child's health-care provider. on the other hand if the fever accompanies a simple cold or virus you can treat the fever as described above and be assured that the fever is only a symptom of the illness. this is not to say that you should ignore a fever. if there are other associated symptoms that are bothersome you should contact your health-care professional. some vaccines given in childhood can cause a low-grade fever within a day or two of getting the injection. this fever is usually self-limited and short-lived. if the reaction seems severe or the skin at the injection site is red hot and painful contact your child's doctor. about 3% of all children between 18 months to 3 years of age will have a seizure (convulsion) with a high fever. of those with a history of febrile seizure approximately one-third will have another seizure associated with another febrile episode. febrile seizures while frightening to the parents are not associated with long-term nervous-system side effects. children used to be prescribed phenobarbital following a febrile seizure as a preventive measure (prophylaxis). this has not been shown to be beneficial and possibly may be harmful so it is not always recommended.
when should i seek medical care for a fever?