What should you know about internal fever?

The phrase is not a separate medical diagnosis. A thermometer can show whether you have a fever, while your other symptoms help a clinician consider possible causes.

Feeling hot from inside can occur during an infection, even when the skin does not feel warm to another person. Chills, sweating, tiredness, headache, muscle aches or reduced appetite may occur alongside a fever. A warm room, exercise, stress, hormonal changes or dehydration can also make you feel overheated without causing a true fever.

Check your temperature with a working digital thermometer and follow its instructions. Record the reading, the time, and any related symptoms. A normal reading does not dismiss severe symptoms, and a raised reading does not by itself reveal the cause. Fever can accompany illnesses such as the common cold, COVID-19, acute bronchitis or cellulitis.

Rest, drink fluids regularly, and choose light clothing while you feel unwell. Keep the room comfortably cool rather than using ice-cold baths, which can trigger shivering. Eat small amounts if you can and avoid strenuous activity until you feel better.

If you need medicine for discomfort or a raised temperature, use only a product suitable for you and follow the label directions. A pharmacist can check the choice when you are pregnant, caring for a child, taking other medicines, or living with a long-term condition. Do not use leftover antibiotics; they do not treat every cause of fever.

Seek urgent medical help for trouble breathing, chest pain, confusion, fainting, a seizure, a stiff neck, a severe headache, a rapidly spreading rash, or signs of serious dehydration such as very little urine and marked weakness.

Arrange medical advice if the fever is persistent, keeps returning, is worsening, or comes with a localised pain, a new rash, repeated vomiting, or difficulty drinking. Babies, older adults, pregnant people, and people with weakened immune systems may need earlier assessment. For a child, seek prompt advice if they are unusually sleepy, difficult to wake, or not drinking.

You could ask: What might explain my temperature and other symptoms? How should I measure and record my temperature? Which warning signs should prompt urgent care? Is any medicine unsuitable with my health conditions or current treatment? If symptoms continue, when should I be reviewed?