Medications can lower a fever, but sometimes it's better left untreated. Fever may play a role in helping your body fight off infections.
A fever is a temporary rise in body temperature. It's one part of an overall response from the body's immune system. A fever is usually caused by an infection.
For most children and adults, a fever may be uncomfortable. But it usually isn't a cause for concern. For infants, however, even a low fever may mean there's a serious infection.
Fevers generally go away within a few days. A number of over-the-counter medications lower a fever. But you don't necessarily need to treat a fever if it's not causing discomfort.
Body temperatures vary slightly from person to person and at different times of day. The average temperature has traditionally been defined as 98.6 F (37 C). A temperature taken using a mouth thermometer (oral temperature) that's 100 F (37.8 C) or higher is generally considered to be a fever.
Depending on what's causing a fever, other fever signs and symptoms may include:
To take a temperature, you can choose from several types of thermometers, including oral, rectal, ear (tympanic) and forehead (temporal artery) thermometers.
Oral and rectal thermometers generally provide the most accurate measurement of core body temperature. Ear or forehead thermometers, although convenient, provide less accurate temperature measurements.
In infants, a rectal temperature, if doable, is somewhat more accurate. When reporting a temperature to your health care provider, give both the reading and the type of thermometer used.
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.
A fever is a particular cause for concern in infants and toddlers. Call your baby's health care provider if your child is:
There's probably no cause for alarm if your child has a fever but is responsive. This means your child makes eye contact with you and responds to your facial expressions and to your voice. Your child may also be drinking fluids and playing.
Call your child's health care provider if your child:
Ask your child's health care provider for guidance in special circumstances, such as a child with immune system problems or with a preexisting illness.
Call your health care provider if your temperature is 103 F (39.4 C) or higher. Seek immediate medical attention if any of these signs or symptoms accompanies a fever:
Typical body temperature is a balance of heat production and heat loss. An area in the brain called the hypothalamus (hi-poe-THAL-uh-muhs) — also known as your body's "thermostat" — monitors this balance. Even when you're healthy, your body temperature varies slightly throughout the day. It can be lower in the morning and higher in the late afternoon and evening.
When your immune system responds to disease, the hypothalamus can set your body temperature higher. This prompts complex processes that produce more heat and restrict heat loss. The shivering you might experience is one way the body produces heat. When you wrap up in a blanket because you feel chilled, you are helping your body retain heat.
Fevers below 104 F (40 C) associated with common viral infections, such as the flu, may help the immune system fight disease and are generally not harmful.
Fever or elevated body temperature might be caused by:
Children between the ages of 6 months and 5 years are at increased risk of a seizure that occurs during a fever (febrile seizure). About a third of the children who have one febrile seizure will have another one, most commonly within the next 12 months.
A febrile seizure may involve loss of consciousness, shaking of limbs on both sides of the body, eyes rolling back or body stiffness. Although alarming for parents, the vast majority of febrile seizures cause no lasting effects.
If a seizure occurs:
If your child doesn't need emergency care, see your child's health care provider as soon as possible for further evaluation.
You may be able to prevent fevers by reducing exposure to infectious diseases. Here are some tips that can help:
To evaluate a fever, your care provider may:
Because a fever can indicate a serious illness in a young infant, especially two months of age or younger, your baby might be admitted to the hospital for testing and treatment.
When a fever lasts for more than three weeks — constantly or on several occasions — and there is no clear cause, it's usually called a fever of unknown origin. In these cases, you may need to see specialists in one or more medical fields for further evaluations and tests.
For a low-grade fever, your care provider may not recommend taking medications to lower your body temperature. These minor fevers may be helpful in reducing the number of microbes causing your illness. Fevers above 102 F (38.9 C) tend to cause discomfort and often require treatment.
In the case of a high fever or a fever that causes discomfort, your care provider may recommend nonprescription medication, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others).
Use these medications according to the label instructions or as recommended by your health care provider. Be careful not to take too much. High doses or long-term use of acetaminophen or ibuprofen may cause liver or kidney damage, and acute overdoses can be fatal. Don't give aspirin to children, because it may trigger a rare, but potentially fatal, disorder known as Reye's syndrome.
These medications will usually lower your temperature, but you may still have a mild fever. It may take 1 to 2 hours for the medication to work. Call your care provider if your fever doesn't improve, even after taking medication.
Your health care provider may prescribe other medications based on the cause of your illness. Treating the underlying cause may lessen signs and symptoms, including fever.
Infants, especially those younger than two months old, might need to be admitted to the hospital for testing and treatment. In babies this young, a fever could indicate a serious infection that requires intravenous (IV) medications and round-the-clock monitoring.
You can try a number of things to make yourself or your child more comfortable during a fever:
Your appointment may be with your family doctor, pediatrician or other care provider. Here's some information to help you get ready for your appointment and know what to expect from your care provider.
For a fever, some basic questions to ask your provider include:
Don't hesitate to ask other questions during your appointment as they occur to you.
Be prepared to answer questions, such as: