Fever in adults

If you or a family member has a fever, it means your body temperature is above normal.

Around 37ºC is normal

A digital thermometer is the best type to use to get an accurate temperature reading.

A fever is usually a normal response of your immune system to a virus or bacterial infection. Most healthy adults can tolerate a fever well.

Fever ranges and symptoms

38–38.9°C – mild fever
With a mild fever you might have flushed cheeks, feel a little lethargic, and be warm to touch. You will generally be able to carry out normal daily activities.

39–39.9°C – high fever
With a high fever you may not feel well enough to go to work, you may have aches and pains, and you’ll feel hot to touch.

40°C or higher – very high fever
With a very high fever you will usually want to stay in bed or be inactive – you won’t feel well enough to carry out normal activities. You may have lost your appetite. You’ll feel hot to touch.

When to see your doctor

Some mild diseases produce very high fevers – and severe illnesses can produce mild fever. Therefore, when considering what medical attention you need, it’s important to look at other symptoms and how unwell you feel.

You should see your doctor if you or a family member:

  • has a very high fever (over 40ºC)
  • is still feverish after three days of home treatment, or seems to be getting sicker
  • is shivering or shaking uncontrollably, or has chattering teeth
  • has a severe headache that doesn’t get better after taking painkillers
  • is having trouble breathing
  • is getting confused or is unusually drowsy
  • has recently travelled overseas.

When it’s urgent

See your doctor or go to the Emergency Department immediately if you notice the following symptoms (along with a fever):

  • Hallucinations
  • Vomiting
  • A stiff neck (they’re unable to put their chin on their chest or have pain when moving their neck forward)
  • A skin rash
  • A rapid heart rate.

Also get medical help if the person has a seizure (fit), or has signs of a seizure about to happen, such as regular twitching or jerking.

Call Healthline 0800 611 116 if you are unsure what you should do.

Fever in pregnancy

If you’re pregnant and have a temperature of 38.5ºC – or any fever lasting for three days or more – you must see your lead maternity carer. They’ll need to monitor the effects of the fever on your baby.

Self care

Most fevers last only three to four days – and a mild fever may not need any treatment at all. 

Try these ideas if your fever is mild and you don’t have any other worrying symptoms:

  • Drink plenty of fluids – water is best.
  • Get plenty of rest.
  • Wear light weight clothes and use lighter bedding. Keep the room temperature normal.
  • Put cool cloths on your face, arms and neck to help you cool down. Don’t use any rapid cooling methods that may make you shiver. (The muscle movement in shivering will actually raise your temperature and can make your fever worse.)
  • You can take paracetamol or ibuprofen every four to six hours to help bring down the fever. (It is important not to get dehydrated if you take ibuprofen, as there is a risk of kidney disease.)
  • Ask someone to check on you regularly to make sure you’re OK.
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