Fever in Adults: Causes, Care and When to See a Doctor

6 min read · Conditions · By the Asthra Health Care team

What is a fever?

A fever is a body temperature higher than normal, usually 100.4°F (38°C) or above when measured with a thermometer. It is not a disease by itself. It is a sign that the body is fighting something, most often an infection. The brain raises the temperature on purpose, because many germs grow less well when the body is warmer.

Feeling hot to the touch is not a reliable test. A digital thermometer placed under the tongue or in the armpit gives a much better reading. Note the temperature and the time, as this record helps your doctor understand the pattern of the fever. Clean the thermometer after each use and wait a few minutes after a hot drink before measuring.

Common causes in India

Most fevers in adults are caused by viral infections such as the common cold, flu or a viral throat infection. These usually settle within three to five days. In the monsoon and just after it, mosquito-borne infections like dengue, malaria and chikungunya become common in Karnataka and Andhra Pradesh.

Other causes include typhoid from contaminated food or water, urinary tract infections, chest infections, and tuberculosis when a low fever lasts for weeks. Less often, fever comes from non-infectious problems such as some autoimmune conditions, certain cancers or reactions to medicines.

• Viral infections: cold, flu, sore throat
• Mosquito-borne: dengue, malaria, chikungunya
• Water and food-borne: typhoid, gut infections
• Other infections: urine, chest, skin, tuberculosis

Symptoms that come with fever

Fever often comes with chills, sweating, body ache, headache, tiredness and poor appetite. The other symptoms give clues to the cause. A runny nose and cough point to a respiratory infection. Burning while passing urine suggests a urine infection. Severe body and joint pain after a mosquito bite season may suggest dengue or chikungunya.

The pattern also matters. A fever that comes with shivering every day or two can point to malaria. A fever that climbs slowly over several days with stomach upset may suggest typhoid. A low evening fever with cough and weight loss over weeks raises concern about tuberculosis. Noting these details helps your doctor choose the right tests.

How doctors find the cause

For a short fever with cold symptoms, a doctor may not need any test. If the fever lasts beyond two to three days, is very high, or comes with other worrying symptoms, the doctor will usually suggest blood tests. A complete blood count shows signs of infection and platelet levels.

Depending on the season and symptoms, the doctor may also order a dengue test, a malaria test, a typhoid test, a urine test or a chest X-ray. Getting tested early helps the right treatment start quickly and avoids unnecessary antibiotics.

Caring for fever at home

Rest, drink plenty of fluids and eat light, easily digested food such as rice gruel, idli, dal and fruits. Water, oral rehydration solution, buttermilk, tender coconut water and clear soups help replace fluid lost through sweating. Wear light cotton clothes and keep the room airy rather than covering up with heavy blankets.

Paracetamol is the usual first choice to bring down fever and ease body ache. Follow the label or your pharmacist's advice and do not take more than the recommended amount, as too much can harm the liver. Sponging with lukewarm water can also make you more comfortable.

Medicines to be careful with

Avoid painkillers like ibuprofen, diclofenac or aspirin for fever during the monsoon unless a doctor has ruled out dengue, as these can raise the risk of bleeding. Antibiotics do not help viral fevers and should be taken only on a doctor's prescription, after the doctor decides a bacterial infection is likely.

Pregnant women, the elderly and people with diabetes, kidney disease, liver disease or weak immunity should see a doctor early for any fever, rather than waiting for it to settle on its own. In older people, infection may show as confusion or weakness with only a mild fever.

When to see a doctor for fever in adults

See a doctor if fever lasts more than two to three days, keeps coming back, or you feel much weaker than you would expect. Take your temperature record and a list of any medicines you have already taken. Seek help the same day if any of the red-flag signs listed below appear. When in doubt, speak to your doctor or pharmacist before taking any medicine.

This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.