A fever in a child is generally considered to be a body temperature of 100.4°F (38°C) or higher. A fever is usually not dangerous and can help the immune system fight infections. However, a fever is considered too high and requires medical attention if:

• The child is younger than 3 months old and has a rectal temperature of 100.4°F (38°C) or higher — immediate medical care is needed.
• The child is 3 months or older and has a temperature higher than 102.2°F (39°C).
• The fever reaches about 105°F (40.6°C) or higher; although tissue damage usually happens only if the fever reaches extremely high levels (around 107°F), a fever of 105°F should prompt a doctor visit.
• The fever lasts more than 2-3 days.
• The child shows serious symptoms such as difficulty breathing, persistent crying, extreme irritability, trouble waking, rash, blue lips or nails, bulging soft spot on an infant’s head, stiff neck, seizure, or other severe signs.
• The child is not drinking liquids, has signs of dehydration, or seems significantly ill.

In healthy children older than 3 months who are alert, drinking well, and playing, a moderate fever up to about 102°F (39°C) is usually not a reason for alarm. In summary, a fever is too high for a child if it is above 102.2°F (39°C) in older infants and children, and if any serious symptoms or concerning signs are present at any fever level. Immediate medical care is necessary for infants under 3 months with any fever of 100.4°F or higher.