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Symptom Guide

Fever

An educational overview of fever, a temporary rise in body temperature that is often a sign the body is responding to an infection or other illness.

Symptom SignFamily MedicineEmergency MedicineFull article

Also known as: high temperature, pyrexia, pyrexia

Educational information only. This explains health information to discuss with a qualified clinician; it is not a diagnosis, prescription, or treatment. Medical Information & Safety.

Overview

Educational academic overview: fever is a regulated rise in the hypothalamic set-point, distinct from hyperthermia. Study material only.

Symptoms

  • feeling hot or shivery
  • sweating
  • headache or aches
  • tiredness

Causes

  • possible categories only — infections such as viral or bacterial illness
  • inflammatory conditions
  • some medicines or immunisations
  • heat-related illness (separate from fever)

Risk factors

  • recent infection or exposure
  • very young or older age
  • weakened immune function

Prevention

  • hand hygiene and staying up to date with recommended vaccines
  • avoiding contact with people who are unwell where possible

Emergency warning signs

  • stiff neck with rash or severe headache
  • difficulty breathing
  • confusion, seizures, or unresponsiveness
  • fever in a baby under 3 months

Evaluation & tests

Educational note: a list of possible causes is not a personal diagnosis. A clinician finds the cause of a fever. This library does not diagnose.

Treatment education

Educational overview: care depends on the cause and is individualized by clinicians. This library does not prescribe.

Self-care

General education: rest, fluids, and monitoring can help mild illness; follow clinician guidance, especially for infants.

When to seek care

Seek care for a fever in a young infant, a very high or persistent fever, or a fever with concerning symptoms.

Last reviewed: 2026-01-01T00:00:00.000Z