Fever: symptoms, causes and when to get help

Fever is a rise in body temperature that can accompany infection, inflammation, heat illness or other health problems.

You may feel hot, flushed, chilly or shivery. Sweating can occur as your temperature comes down. Tiredness, headache, aching muscles, thirst and reduced appetite may come with it, but the pattern varies with the underlying problem. A thermometer reading is useful, yet how you feel and any accompanying symptoms also matter.

Seek urgent medical help for fever with trouble breathing, new confusion, severe drowsiness, a stiff neck, a seizure, a widespread purple or non-fading rash, severe headache, chest pain, or signs of dehydration such as very little urine. Babies, people who are pregnant, older adults and people with reduced immunity may need earlier assessment. Heat exposure followed by confusion, collapse or hot dry skin also needs emergency care.

Fever is a body response rather than a diagnosis. Respiratory infections, throat infections, urine infections, skin infections and stomach illnesses can all produce it. Other possibilities include heat-related illness and inflammatory conditions. The list below is not a ranking: symptoms, recent travel, sick contacts, medicines and examination findings help narrow the cause. Fever can be part of the presentation of pneumonia, scarlet fever, tonsillitis, tuberculosis and urinary tract infection.

A clinician will ask when the fever began, whether it comes and goes, and what other symptoms are present. They may check temperature, pulse, breathing, hydration and areas such as the throat, ears, chest, abdomen or skin. Depending on the findings, testing may include a urine sample, blood tests, a swab or imaging. Not every fever needs every test; the choice is guided by the clinical picture.

Rest, fluids and light clothing can make a fever easier to manage. A clinician or pharmacist can advise on fever-relieving medicine that is appropriate for the person’s age, health conditions and other medicines. Treatment may also target the cause: for example, bacterial infections may need prescribed antibiotics, while heat illness needs cooling and urgent assessment when severe. Do not use leftover antibiotics or give medicines intended for adults to a child without advice.

Handwashing, safe food handling, clean drinking water and staying home when acutely unwell can reduce the spread of some infections. Keep routine vaccinations up to date when they are appropriate for you. In hot conditions, take breaks in cooler places, drink fluids regularly and avoid strenuous activity when you feel unwell. Travel precautions should reflect your destination and planned activities.

Make a note of cough, sore throat, rash, vomiting, diarrhoea, pain on urination, abdominal pain, joint pain or a new skin area that is red and tender. Also record fluid intake, urine output and whether symptoms are improving or worsening. This information is useful if you need a consultation.

Many fevers settle as the underlying illness improves, but a fever that persists, returns after improving, or develops with new symptoms deserves review. Prompt care can identify problems such as dehydration, a focused infection or a more serious systemic illness before they become harder to manage.