Most fevers are caused by common viral or bacterial infections such as colds, flu, COVID-19, urinary infections, or — in some regions — malaria. A raised temperature (generally above 38C/100.4F) is a normal immune response and on its own is not dangerous in an otherwise healthy adult. Rest, fluids, and an over-the-counter fever reducer recommended by a pharmacist usually help comfort while your body recovers.
Seek urgent care or call your local emergency number if a fever comes with a stiff neck, a rash that does not fade when pressed, confusion or drowsiness, severe breathlessness, a seizure, or signs of dehydration. A fever above 39.5-40C that does not respond to medicine, or any fever lasting more than 3 days, should be checked by a clinician.
Some people need earlier review: infants and young children, pregnant people, older adults, and anyone with a weak immune system or recent travel to a malaria area. A doctor or pharmacist can advise on safe treatment and whether testing is needed. This is general information, not a diagnosis.