A fever is a temporary increase in your body’s temperature, signaling that your immune system is actively working to fight off an infection or illness. It is not an illness itself, but rather a symptom that your body is responding to a perceived threat, such as bacteria or viruses. Raising the body’s temperature helps create an environment less favorable for many common pathogens to thrive, while also activating immune cells like white blood cells to become more efficient at combating infection.
Fever Duration for Different Age Groups
The acceptable duration of a fever varies significantly with age, with some age groups warranting immediate medical attention regardless of how long the fever has been present. For infants under 3 months of age, any fever of 100.4°F (38°C) or higher, measured rectally, requires immediate medical evaluation. This is due to their underdeveloped immune systems, which make them more susceptible to serious infections that can worsen rapidly.
For young children between 3 months and 3 years old, a fever often caused by viral illnesses may last for 2 to 3 days, with temperatures often ranging between 101°F and 104°F (38.4°C and 40°C). Medical attention is advised if a child in this age group has a fever of 102.2°F (39°C) or higher, especially if there are no obvious symptoms like a runny nose, or if the fever persists for more than 1 or 2 days. If a fever without other symptoms lasts over 48 hours for children aged 6 to 12 months, or if a fever with symptoms lasts more than 3 days, contact a doctor.
For older children and adults, a fever lasting a few days is generally not a cause for alarm, as it often indicates the body is fighting a viral infection like a cold or flu. Most fevers in adults typically resolve within 1 to 3 days. However, if a fever in an older child or adult lasts longer than three days, or if it is 103°F (39.4°C) or higher, seeking medical advice is recommended. A persistent or recurring fever lasting or recurring for up to 14 days may also indicate a more serious underlying condition.
Warning Signs and When to Get Help
Beyond fever duration, certain accompanying symptoms serve as red flags, indicating a need for immediate medical attention regardless of how long the fever has been present.
In older children and adults, signs that necessitate immediate medical evaluation include:
A severe headache, stiff neck, or pain when bending the head forward, as these can indicate meningitis.
A rash, especially one that looks like small bleeding spots under the skin and does not fade when pressed, is another serious sign.
Difficulty breathing or chest pain.
Persistent vomiting.
Signs of dehydration, such as decreased urination or lack of tears.
Confusion.
Unusual sensitivity to bright light.
Seizures.
A child who is listless, unusually irritable, or has poor eye contact.
Comfort Measures for Fever at Home
When a fever does not require immediate medical attention, several comfort measures can help manage symptoms at home. Staying well-hydrated is important, as fever can lead to fluid loss through sweating. Drink plenty of water, clear broths, or electrolyte solutions to prevent dehydration. Infants under 6 months should continue to receive breast milk or formula.
Rest is another important component of recovery, as physical activity can further raise body temperature. Dressing in light clothing and keeping the room temperature cool can also help promote comfort and heat loss. A lukewarm bath or sponge bath can help cool the body, but avoid cold baths or showers, as they can cause shivering, which paradoxically increases body temperature. Over-the-counter fever reducers like acetaminophen or ibuprofen can be used to alleviate discomfort. Follow dosage instructions carefully and consult a doctor, especially for children under 2 years old. Aspirin should not be given to children due to the risk of Reye’s syndrome.