Fever

AAbout Fever and the ED Workup

Fever is a sign, not a diagnosis. Infection or inflammation tells the brain to raise the body’s temperature setting. The body may shiver and seek warmth until it reaches that new setting. When the setting falls again, sweating helps release heat.

This is different from heat stroke. During fever, the body’s thermostat has moved upward. During heat illness, outside heat overwhelms a normal setting. The thermometer number alone cannot reliably separate them.

An initial evaluation can be reassuring without predicting the whole course. Early sepsis can evolve after normal first tests. Some deep infections can do the same. In young infants, even validated low-risk pathways miss some invasive bacterial infections.

For most people older than three months, a higher fever does not reliably mean a more dangerous illness. How the person looks, breathes, drinks, urinates, and responds matters more.

FFirst Steps and Evidence-Based Home Care

1. Treat discomfort, not a target number

Fever medicine can improve comfort. It has not been shown to shorten the illness or improve major outcomes. If it was recommended, use the exact product, dose, and schedule in the discharge plan. Dosing children by weight reduces errors.

Do not create an alternating schedule unless a clinician has written it clearly. Alternating regimens are complicated, and recommended schedules vary widely.

2. Let a comfortable person sleep

Do not wake a sleeping child only to chase the thermometer number. Comfort should guide treatment, and sleep is restorative.

3. Use comfortable clothing and fluids

Dress comfortably and encourage enough fluid to maintain drinking and urination. Cold baths or sponging can cause shivering and distress because they fight the raised temperature setting.

4. Do not count on fever medicine to prevent a seizure

Simple febrile seizures do not cause brain damage. They do not harm learning or behavior. Fever medicines do not prevent seizures during future illnesses.

TTimeline and Expected Recovery Course

The fever’s course depends on its cause. In adults, influenza fever usually lasts about three days but can last up to eight. Cough and tiredness may last up to two weeks. Common-cold symptoms often peak at two to three days and last seven to ten days; fever is uncommon in an adult cold.

The temperature coming down after medicine does not prove the illness is harmless. Failure to come down is only a modest warning for bacteria in the blood. It cannot diagnose that problem. Watch the person and the full symptom pattern, not only the thermometer.

Fever that lasts more than three to five days in a child, returns after going away, or comes with a new symptom needs reassessment. Adults prescribed treatment for an infection should return for fever that persists beyond two to three days, returns, or comes with new symptoms.

EEmergency Red Flags: Return Immediately

Return to the emergency department for any of these:

• Any fever of 38 °C / 100.4 °F or higher in a baby under three months.
• Trouble waking, confusion, unusual sleepiness, or inconsolable behavior.
• Trouble breathing or the skin pulling inward between the ribs.
• Poor drinking, much less urine, a very dry mouth, or other signs of dehydration.
• A purple or red rash that does not fade when pressed.
• Fever with severe shaking chills, a new rash, or a new or worsening symptom in an adult.
• Any fever during chemotherapy, because treatment for possible infection is time-sensitive.

This list does not cover everything. If the person looks very ill or is getting worse, return to the emergency department.