You have a fever when your temperature rises above its normal range. What's normal for you may be a little higher or lower than the average temperature of 98.6 F (37 C).
Depending on what's causing your fever, additional fever symptoms may include:
* Sweating
* Shivering
* Headache
* Muscle aches
* Loss of appetite
* Dehydration
* General weakness
High fevers between 103 F (39.4 C) and 106 F (41.1 C) may cause:
* Hallucinations
* Confusion
* Irritability
* Convulsions
Fever-induced seizures
A small percentage of children younger than age 5 experience fever-induced seizures (febrile seizures). The signs of febrile seizures, which occur when a child's temperature rises or falls rapidly, include a brief loss of consciousness and convulsions.
Although these seizures can be alarming, most don't cause any lasting effects. Febrile seizures often are triggered by a fever from a common childhood illness such as roseola, a common viral infection that causes a high fever, swollen glands and a rash.
When to see a doctor
Fevers by themselves may not be a cause for alarm — or a reason to call a doctor. Yet there are some circumstances when you should seek medical advice for your baby, your child or yourself.
Infants
An unexplained fever is greater cause for concern in infants and in children than in adults. Call your baby's doctor if your baby has a fever of 101 F (38.3 C) or higher. Also call your baby's doctor if your baby:
* Is younger than 3 months of age.
* Refuses to eat or drink.
* Has a fever and unexplained irritability, such as marked crying during a diaper change or when moved.
* Has a fever and seems lethargic and unresponsive. In infants and children younger than age 2, these may be signs of meningitis — an infection and inflammation of the membranes and fluid surrounding the brain and spinal cord. If you're worried that your baby might have meningitis, see your doctor immediately.
* Is a newborn and has a lower than normal temperature — less than 97 F (36.1 C). Very young babies may not regulate their body temperature well when they are ill and may become cold rather than hot.
Children
Children often tolerate fevers well, although high temperatures may cause parents concern. It's best to be guided more by how your child acts than only by temperature measurement. There's probably no cause for alarm if your child has a fever but is responsive — making eye contact with you and responding to your facial expressions and to your voice — and is drinking fluids and playing.
Call your child's doctor if your child:
* Is listless or irritable, vomits repeatedly, has a severe headache or stomachache, or has any other symptoms causing significant discomfort.
* Has a fever after being left in a hot car. Seek medical care immediately.
* Has a fever that persists longer than one day (in children younger than age 2) or longer than three days (in children ages 2 and older).
Ask your doctor for guidance if you have special circumstances, such as a child with immune system problems or with a pre-existing illness. Your doctor also may recommend different precautions if your child has just started taking a new prescription medicine.
Sometimes, older children can have a lower-than-normal temperature. This can happen to older children with severe neurological impairments, children with a life-threatening bacterial infection in the blood (sepsis) and children with suppressed immune systems.
Adults
Call your doctor if:
* Your temperature is more than 103 F (39.4 C)
* You've had a fever for more than three days
In addition, seek immediate medical attention if any of these signs or symptoms accompanies a fever:
Severe headache
Severe throat swelling
Unusual skin rash, especially if the rash rapidly worsens
Unusual sensitivity to bright light
Stiff neck and pain when you bend your head forward
Mental confusion
Persistent vomiting
Difficulty breathing or chest pain
Extreme listlessness or irritability
Abdominal pain or pain when urinating
Any other unexplained signs or symptoms