A fever signals an elevated body temperature, which is often a natural response of the immune system to fight off an infection or illness. This rise in temperature can indicate that the body is actively working to eliminate invading microbes. While many fevers are not serious and resolve on their own, some instances can point to an urgent medical situation requiring professional evaluation.
Key Indicators for Emergency Care
Specific temperature thresholds can indicate the need for emergency room evaluation, varying significantly by age. For infants under three months old, a rectal temperature of 100.4°F (38°C) or higher requires immediate medical attention, as it may signal a serious bacterial infection. Such young infants have developing immune systems, making them more vulnerable to severe complications. Even a slight temperature elevation in this age group can be a concern.
For infants aged three to six months, a fever of 102°F (38.9°C) or higher warrants medical advice, especially if accompanied by irritability, poor feeding, or lethargy. Children over six months should seek medical advice for fevers of 103°F (39.4°C) or higher. In older children, a fever exceeding 105°F (40.5°C) that does not decrease after fever-reducing medication, or a fever above 105°F, necessitates an emergency department visit.
Adults should seek urgent care if a fever rises above 103°F (39.4°C) or persists for more than a few days. A fever of 105°F (40.5°C) or higher in healthy adults warrants immediate emergency room evaluation. High fevers can lead to complications such as dehydration and delirium.
Accompanying Symptoms Requiring Immediate Attention
Beyond temperature readings, other symptoms, when present with a fever, signal an immediate need for emergency medical care. A severe headache accompanied by a stiff neck, particularly with sensitivity to light, can indicate serious conditions like meningitis. Confusion, disorientation, or changes in mental status, such as difficulty waking or extreme sleepiness, are also serious signs.
Difficulty breathing or shortness of breath alongside a fever is a concerning symptom. An unexplained or rapidly spreading rash, especially one that does not blanch (turn white) when pressed, can be a sign of a life-threatening illness. Persistent vomiting or diarrhea, particularly if it leads to signs of dehydration, also necessitates emergency care.
Seizures occurring with a fever, known as febrile seizures, are common in children aged six months to five years. While often harmless, a first-time seizure, one lasting longer than five minutes, or one accompanied by breathing difficulties, neck stiffness, or extreme lethargy, requires emergency medical attention.
Special Considerations for Vulnerable Populations
Certain populations face heightened risks from fever, necessitating different thresholds for seeking medical attention. Infants, especially those under three months, are particularly vulnerable because their immune systems are still developing. Any fever in a newborn under one month old (100.4°F / 38°C or higher rectally) should prompt an immediate visit to the emergency department. For infants one to three months old with the same temperature, a pediatrician should be seen promptly, and if unavailable, the ER is recommended.
Elderly individuals are more susceptible to severe complications from fever due to age-related declines in their immune systems. A fever in an older adult, even a seemingly mild one, can indicate a serious underlying infection. Fevers of 103°F (39.4°C) or higher in the elderly, especially with accompanying symptoms, require immediate medical attention.
Individuals with compromised immune systems, such as those undergoing chemotherapy, organ transplant recipients, or people with conditions like HIV/AIDS, diabetes, or heart disease, should seek medical attention for any fever. They may not mount a strong fever response even with a severe infection and are at greater risk for serious complications. These patients may have lower thresholds for seeking care and should contact their healthcare provider for fevers of 101°F (38.3°C) or higher.
When Other Medical Attention is More Appropriate
Many fevers do not require an emergency room visit. For adults, a mild fever without severe accompanying symptoms often indicates a common viral infection. In such cases, home care, including rest, drinking plenty of fluids, and using over-the-counter fever-reducing medications, is usually sufficient.
If a fever in an adult persists for more than three days despite home treatment, or if it reaches 102°F (38.9°C) without other severe symptoms, contacting a primary care physician or visiting an urgent care center is appropriate. For older children, a fever lasting more than two days, or a temperature of 102°F (38.9°C) that persists, can often be addressed by a pediatrician or at an urgent care clinic. Urgent care centers are equipped to handle fevers with symptoms that warrant medical attention but are not life-threatening.