Data from millions of users of the ZOE COVID Symptom Study app has shown that fever can be a symptom of COVID-19. Here’s how to spot it and what it feels like.

What is fever like in COVID-19?

The COVID Symptom Study app found that around four in ten people reporting symptoms of COVID-19 have a high temperature (fever).

Fever is not necessarily a bad thing. It’s a normal response to infection, as raising your body temperature helps your immune system fight it off. 

If you’re under 65, having a temperature over 37.8°C is likely to be a sign of COVID-19. If you’re over 65 or very thin, your normal body temperature is likely to be lower, so a reading over 37.4°C should be considered to be a potential symptom.

You can measure your temperature at home using a thermometer - read our blog post to find out how. An in-ear thermometer is best but an oral (mouth) thermometer is fine. Other devices like smartphones may not be so reliable. 

If you don’t have a thermometer, the key sign to look out for is feeling hotter than usual, particularly on your chest or back. You may also be shivery or have chills.

It’s also important to know that there is no one ‘normal’ body temperature, so get in the habit of checking yours regularly to know what’s usual for you. Body temperature can also be affected by hormones, for example in women who are going through the menopause.

When does fever happen in COVID-19?

When it does occur, fever usually happens in the first week of illness and tends to go quite quickly. However, some people with long-lasting symptoms (long COVID) have reported having recurring fever/chills.

How common is fever in COVID-19?

Fever is a reasonably common symptom of COVID-19, affecting an average of four in ten (40%) of children and adults at some point in their illness. 

Importantly, this means that most people (60%) with COVID-19 will not have a fever, even though it is considered to be one of the three ‘classic’ symptoms of the disease, along with persistent coughing and loss of smell (anosmia).

Fever usually occurs along with other symptoms, and only around one in twenty people with COVID-19 experience fever as their only symptom. 

What other symptoms of COVID-19 are common alongside fever?

Fever is highly likely to occur alongside fatigue (tiredness) and headaches. It often comes together with persistent coughing, chest pain, shortness of breath, sore throat, skipped meals, unusual muscle pains, dizziness and diarrhoea.

Depending on your age and sex, you should contact your doctor if you have multiple different symptoms of COVID-19 in the first week of being ill.

What should I do if I have a fever and think it might be COVID-19?

If you have a high temperature, even for just a short time, it could be COVID-19. You should:

• Follow the NHS guidelines and self-isolate at home to help protect the people around you and the wider community.
• Book a COVID test as soon as possible, either through the app or the NHS.
• Download the ZOE COVID Symptom Study app and start logging your health daily, if you’re not already, to help us understand more about how COVID-19 affects people and contribute to life-saving scientific research.
• Check out our tips on looking after yourself if you are sick with COVID-19, monitoring your health at home and staying hydrated.
  

A fever is your body’s natural response to infection, so it doesn’t necessarily need treating with drugs. If you are an adult and have a fever with COVID-19 you should:

• Get lots of rest
• Stay hydrated by drinking plenty of fluids
• Wear light clothes and avoid bundling yourself up in jumpers and blankets
• Take paracetamol or ibuprofen if you are feeling very uncomfortable, especially if your fever is stopping you from eating or drinking
  

The NHS has more detailed advice for what to do for children with fever.

You should get medical help if your temperature is very high (over 39°C), if it does not come down after several days, or if you have any other concerning symptoms like breathing problems or sudden confusion.

Stay safe and keep logging.