About this symptom
A fever is a body temperature higher than normal. It is not a disease: it usually means the body is fighting an infection. Body temperature rises and falls through the day, and is usually highest in the evening.
Most fevers come from simple infections and pass without harm. Other causes include some medicines, inflammatory conditions and, less often, cancers. Sometimes a fever goes on for days or weeks with no clear cause, and then it needs tests.
This page is about adults. For a baby or child, read Fever in children, because the ages and signs to watch for are different.
Possible causes
This is not a diagnosis. These are the causes doctors think about, with the ones that are most urgent to rule out first.
- SepsisA severe reaction to an infection. A high or low temperature with confusion, very fast breathing, uncontrollable shivering, blotchy or blue skin, or very little urine.Read about it
- MeningitisFever with a very bad headache and a stiff neck, sometimes with confusion, a seizure or a rash that does not fade when pressed.Read about it
- DengueHigh fever with a bad headache, pain behind the eyes, and aching muscles and joints. The danger signs often come as the fever goes down.Read about it
- MalariaFever with shivering, sweating, headache and muscle pain, usually 7 to 18 days after a mosquito bite but sometimes months later. It needs quick treatment.Read about it
- Typhoid feverA high fever that lasts for days, with tiredness, headache, tummy pain and constipation or loose motions. Usually spread by contaminated food or water.Read about it
- PneumoniaFever with a cough and trouble breathing. A chest X-ray helps the doctor to tell.Read about it
- Urinary tract infectionFever together with pain when passing urine. A urine test can confirm it.Read about it
- FluA common viral cause: fever with a cough or sore throat. Even a high fever from a simple viral illness is not always serious.Read about it
When to get help
Also get emergency care for:
- A rash that does not fade when pressed
- Blue, pale or blotchy skin, uncontrollable shivering, or passing hardly any urine all day
- Severe tummy pain, repeated vomiting, bleeding from the gums or nose, or blood in vomit or stools, even if the fever has gone down: these can be warning signs of severe dengue
See a doctor soon, the same day if the fever is very high, if you have:
- A fever that has lasted more than 2 to 3 days
- A temperature of 39.4°C (103°F) or higher that stays up or keeps rising
- Fevers that come and go for a week or more, even if they are mild
- A new rash or bruises, or pain when passing urine
- A fever if you have diabetes, a heart or lung condition, sickle cell disease or a weak immune system
- A fever after travel to another country, especially one with malaria
A mild fever with a cold or sore throat, in someone who is otherwise well and drinking fluids, can be looked after at home for a day or two.
What you can do at home
With any emergency sign, do not stay at home: get help first.
Do
- Rest, and drink plenty of fluids such as water and soup
- Wear one light layer, and use a fan if the room is hot
- Try a lukewarm sponge bath, and paracetamol if you are uncomfortable
- Note when the fever began, the highest reading and any new symptoms
Do not
- Do not bundle up in blankets when you have chills
- Do not use cold baths, ice or alcohol rubs, as shivering can raise your temperature
- Do not take aspirin or ibuprofen without asking a doctor, as they can raise the risk of bleeding if the cause is dengue
- Do not wait for the fever to pass if any sign above appears
What the doctor will do
The doctor will ask how long the fever has lasted, how high it has been, and what else you have noticed, such as a cough, pain when passing urine, a rash or tummy upset. They will ask about travel, medicines and long-term illness, and examine you from head to toe.
Tests depend on the likely cause. They may include:
- Blood tests, such as a complete blood count, and tests for a suspected infection such as dengue or typhoid
- A urine test
- A chest X-ray
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Once the fever comes down, the danger is over.”What is true?
Fact
In dengue, the severe symptoms often come after the fever has gone away. Watch for severe tummy pain, repeated vomiting, bleeding from the gums or nose, or blood in vomit or stools, and get care immediately if any appear.
Myth“A cold bath, ice or rubbing the body with spirit brings a fever down fastest.”What is true?
Fact
Cold baths, ice and alcohol rubs are best avoided, because they can make you shiver, and shivering can raise the temperature inside the body. A lukewarm sponge bath, light clothing and a fan are gentler and work better.
Myth“Cover up well and sweat it out.”What is true?
Fact
Bundling up when you have chills does not help. One light layer and one light blanket are enough, with a fan if the room is hot.
Myth“A high fever will damage the brain.”What is true?
Fact
Brain damage from fever is unlikely unless the temperature goes above 42°C (107.6°F). A simple viral illness can cause a high fever without being serious. What matters more is the cause and any other signs, so go by the warning signs and not by the number alone.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
What temperature counts as a fever in an adult?
Body temperature changes through the day and is usually highest in the evening. In an adult, a mouth temperature above about 37.2 to 37.5°C (99 to 99.5°F), depending on the time of day, counts as a fever. See a doctor sooner if it stays at or above 39.4°C (103°F).
Is it safe to take paracetamol for a fever?
Paracetamol is the usual choice to ease the discomfort of a fever, and it is also the pain relief advised in dengue. Follow the pack or your doctor's advice. Ask a doctor before taking aspirin or ibuprofen, because they can raise the risk of bleeding if the cause is dengue.
When should I get tested for dengue, typhoid or malaria?
A fever that lasts more than 2 to 3 days, or comes with the signs above, is a reason to see a doctor, who will decide which blood tests you need. Do not wait for the fever to pass. Malaria is an emergency and needs quick treatment.
What should I do while waiting to see the doctor?
Rest, drink plenty of fluids, and wear light clothing. Paracetamol can ease the discomfort. Keep a note of your temperature and any new symptoms, and get help straight away if any emergency sign appears.
