Fever refers to any raised temperature, i.e. a temperature that is higher than normal. Normal body temperature is 37 degrees Celsius (37C) , which is 98.6 degrees Fahrenheit (98.6F).

A fever may be considered ‘normal’ when it is caused by:

  • Exposure to very high temperatures (e.g. hot climates)
  • Strenuous exercise
  • Anxiety or excitement
  • Menstrual cycle (temperature is raised by up to 1C after ovulation)

…these will tend to cause only a slightly raised temperature, usually 1C or so, but can sometimes cause dangerously high temperatures (temps above 39C can be quite dangerous).

Fever is most commonly caused by infections such as:

  • Colds and Flu
  • Viral “pandemic” infections like Covid-19
  • Upper Respiratory infections (throat infection, tonsillitis, ear infection, etc.)
  • Bronchitis and pneumonia
  • Tuberculosis (TB)
  • Gastroenteritis
  • Urinary Tract Infections (UTIs) – bladder and kidney infections
  • Skin infections (e.g. cellulitis)
  • Meningitis (infection of the membrane surrounding the brain)
  • Malaria
  • HIV

Other illnesses and conditions can cause fever, such as:

  • Rheumatoid arthritis
  • Systemic Lupus Erythematosus (SLE)
  • Inflammatory Bowel Disease (IBD)
  • Cancer (any type)

Infections are by far the most common cause of fever and this is what doctors mainly look for. Your doctor will ask for details of any and all associated symptoms and will then perform a careful examination. Tests are only done when the diagnosis is unclear, but may include:

  • Chest X-ray (to assess the lungs)
  • Blood tests for malaria
  • Urine tests
  • Lumbar puncture – where fluid from around the spinal cord and brain is removed, via a needle inserted into the lower back (done when considering meningitis)

In children, high fever may cause seizures, known as ‘febrile seizures’ or ‘febrile convulsions’. It is important to bring down children’s fever as quickly as possible, using tepid sponging (sponging the child with lukewarm water, ideally with a slight breeze over the child), paracetamol (Panado) and anti-inflammatory medicines such as ibuprofen (Brufen). These simple measures can be extremely important and so every parent should know how to treat a high fever.

Fever (raised temperature) is a common symptom that is most-often caused by some form of infection. Identifying the cause is important because while most causes are self-limiting and benign, some are serious and even life-threatening.