koorts

Koorts, often called fever in English, is a temporary elevation of body temperature above the normal daily range. It is usually defined as a body temperature of 38.0°C (100.4°F) or higher measured orally; rectal measurements are typically about 0.3°C higher. Fever reflects the body's response to infection, inflammation, or other stressors and is a common symptom rather than a disease itself. Most fevers resolve within a few days as the underlying cause is treated or runs its course.

Fever most commonly results from infections, particularly viral or bacterial illnesses. Other causes include inflammatory conditions, autoimmune diseases, cancer, reactions to medications, or heat-related illnesses. Symptoms accompanying fever can include shivering or sweating, headache, muscle aches, fatigue, loss of appetite, and dehydration. In young children, fever can be accompanied by irritability or poor feeding; in older adults, fever may be less pronounced.

Diagnosis typically begins with measuring temperature and a clinical history and examination. Additional tests are guided by symptoms, age, and risk factors, and may include blood tests, urine tests, chest imaging, or targeted cultures. Most fevers do not require antibiotics or specific treatment beyond rest, fluids, and fever-reducing medications such as paracetamol or ibuprofen, unless a bacterial infection or other cause warrants it. Aspirin is generally avoided in children due to the risk of Reye syndrome.

Seek medical advice promptly for certain situations: fever in infants under three months, fever lasting more than a few days, very high fever (for example above 39–40°C / 102–104°F), severe dehydration, persistent vomiting, confusion, stiff neck, severe chest pain, or signs of a serious illness such as difficulty breathing or seizures. In people with weakened immune systems or chronic conditions, medical evaluation for fever is advised even with milder symptoms.