A temporary rise in body temperature is commonly known as a fever. A fever often indicates the immune system is working to combat infections or inflammation. The body’s “thermostat” in the hypothalamus regulates this process by resetting to a higher temperature. While a fever can signal illness, its intensity is not solely determined by the temperature reading itself.
Measuring Body Temperature Accurately
Accurate body temperature measurement is important. Digital thermometers use heat sensors and can be used orally, rectally, or in the armpit. Rectal temperatures are generally the most accurate, especially for infants under 3 months, as they provide a core body temperature reading. Oral readings are typically accurate for older children and adults if the mouth remains closed. Temporal artery (forehead) and tympanic (ear) thermometers offer quick, non-invasive readings, though their accuracy can vary, and armpit temperatures are often the least reliable.
Understanding Fever Thresholds
A “normal” body temperature typically ranges from 97.7°F (36.5°C) to 99.5°F (37.5°C), but it can vary based on the individual, time of day, and activity level. A fever is defined as a body temperature of 100.4°F (38°C) or higher when measured orally. For infants under 3 months, a rectal temperature of 100.4°F (38°C) or higher is considered a fever and warrants immediate medical attention.
For young children aged 3 months to 3 years, a temperature above 102.2°F (39°C) is typically a cause for concern. If a child in this age group has a fever lower than 102.2°F but displays other concerning symptoms, medical advice should be sought. In older children and adults, a fever of 100.4°F (38°C) or higher is considered elevated. Adults should contact a healthcare provider if their temperature reaches 103°F (39.4°C) or higher.
Recognizing Concerning Symptoms
While temperature is a key indicator, other accompanying symptoms can signal a more serious condition alongside a fever. These include:
- Lethargy or extreme drowsiness, where an individual is difficult to wake or appears unusually sluggish.
- Difficulty breathing, including rapid or labored breathing, or chest pain.
- A new or unusual rash, especially one that does not fade when pressed.
- Persistent vomiting or an inability to keep fluids down can lead to dehydration, which can worsen a fever and its associated symptoms.
- Signs of dehydration include reduced urination, dry mouth, or sunken eyes.
- A severe headache, particularly when combined with a stiff neck.
- Mental confusion, strange behavior, altered speech, or seizures accompanying a fever are serious symptoms that necessitate prompt medical evaluation.
When to Seek Medical Attention
Knowing when to seek medical attention for a fever is important. For infants under 3 months, any rectal temperature of 100.4°F (38°C) or higher requires immediate medical evaluation, even if no other symptoms are present. For children between 3 months and 3 years, seek emergency care if their temperature is above 102.2°F (39°C), especially if it persists for more than two days or is accompanied by symptoms like extreme fussiness, difficulty waking up, or inability to keep fluids down.
Older children and adults should contact a healthcare provider if a fever lasts longer than three days, or if it reaches 103°F (39.4°C) or higher. Immediate medical attention is necessary for any age if a fever is accompanied by severe symptoms such as difficulty breathing, a stiff neck, severe headache, confusion, seizures, persistent vomiting, or a rash that does not fade. Individuals with compromised immune systems or pre-existing medical conditions should consult their doctor for any fever, regardless of the temperature.
Immediate Home Care for Fever
While monitoring a fever, home care measures can help manage symptoms and provide comfort. Staying well-hydrated is important, as fever can lead to fluid loss; drinking plenty of water, clear broths, or diluted juices is recommended. Rest is also beneficial, as activity can raise body temperature and the body needs energy to recover. Dressing in light clothing and keeping the room at a comfortable, cool temperature can help dissipate heat.
Over-the-counter fever reducers such as acetaminophen or ibuprofen can be used to alleviate discomfort, but it is important to follow dosage instructions based on age and weight. Acetaminophen is generally safe for all ages, while ibuprofen should not be given to infants under 6 months old. Avoiding aspirin in children and teenagers is recommended due to the risk of Reye syndrome. These measures aim to provide temporary relief and comfort, but they do not replace professional medical advice when needed.