Here’s what you need to know about a high temperature
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Dr Ravi says...
Ravi Assi is a qualified in-house doctor at WW UK.
“With the current coronavirus (COVID-19) pandemic, early detection of a high temperature is vital as it is one of the three main symptoms associated with the virus.
“The main symptoms of coronavirus are:
- A high temperature
- A new, continuous cough
- A loss or change to your sense of smell or taste
“Most people with coronavirus have at least one of these symptoms.1
“Normal human body temperature is approximately 37°C and a high temperature (also known as a fever) is usually when your body temperature is 37.8°C or higher. Early detection would enable you to self-isolate and/or get a test to check if you have coronavirus. In addition to the physical signs such as shivering and sweating, a thermometer is a useful way to find out if you have a fever.
“It’s important to note that fever itself is not a disease, but a symptom. Many things can cause a high temperature, but it is predominantly caused by your body fighting an infection. An example of this is the seasonal flu which usually occurs between December and March, although outbreaks can happen as early as October and as late as May. Having a thermometer at home ensures you can check your temperature quickly and easily to help with diagnosis and treatment.”2
What is a high temperature?
A ‘normal’ body temperature is different for everyone. However, a high temperature is usually considered to be 37.8°C or above.
A number of things can cause a high temperature, but usually it’s the body’s natural response to fighting an infection, like a cough or a cold.
If a thermometer reading shows that your temperature is 37.8°C or above, you may have a high temperature. Other symptoms include: shivering (chills), sweating more than usual, and your chest or back feeling hotter than usual.
It’s important to note that if you feel hot or shivery, you may have a high temperature even if a thermometer says your temperature is below 37.8°C.3
What can cause a high temperature?
Although the most common causes of fever are common infections such as colds and gastroenteritis, other medical causes include:
- Infections of the ear, lung, skin, throat, bladder, or kidney
- Conditions that cause inflammation
- Side effects of drugs
Other causes of fever include:
- Blood clots
- Autoimmune diseases
- Hormone disorders such as hyperthyroidism
- Illegal drugs such as amphetamines and cocaine4
Can anything other than illness cause a high temperature?
It’s completely normal for body temperature to fluctuate during the day. Physical activity, eating, drinking, hot baths and strong emotions can all affect your core body temperature.
Other factors that affect body temperature include metabolic rate, weight, age, hormones, pregnancy, and gender.
Eating can lead to a slight increase in body temperature, particularly when you consume foods containing more fat, protein and carbohydrates. Fat moves slowly through the digestive system and complex carbs like brown rice are harder to digest - which means they require more energy to digest, generating heat in the process.
Drinking alcohol can also lead to a rise in body temperature. If you’ve ever looked or felt flushed after a few drinks, that’s because alcohol is a natural vasodilator - that is, it causes your blood vessel to widen, sending blood to the surface of your skin. You may initially feel warm, however vasodilation ultimately has a cooling effect.
Foods containing high levels of water - like fruit and leafy greens - are more likely to cool you down. This is because they travel through the digestive system quickly and with relative ease, requiring less energy and therefore generating less heat.5
Physical activity generates heat. The greater the intensity and duration of exercise, and the more muscle tissue that is used, the more heat that is generated. The body’s response to this is to increase the flow of blood to the skin, where it can cool. Body temperature may increase slightly, but should return to normal fairly soon after you’ve completed your workout.6
Certain emotional states can also make you feel hot under the collar, such as stress, anger or embarrassment. That’s because your metabolism speeds up, and a by-product of metabolism is heat. For example, when you get angry, typically your heart rate quickens and your blood pressure rises. With more blood flowing through your body, more blood flows at the surface of your skin, making you look and/or feel flushed. your skin flushes and body temperature may temporarily rise.7
Treating a high temperature
If you have a high temperature, stay at home, get plenty of rest and drink plenty of water. You can also take paracetamol to reduce symptoms, if you like.8 Please note, this advice is for adults. For advice about fever in children, visit this NHS page.
If you're worried about your symptoms and require medical advice, use the NHS 111 online coronavirus service or call 111 if you cannot get help online.
Dr Ravi’s top tip
“When dealing with a fever, it’s essential to stay hydrated. This is because a fever can draw moisture out of your body, causing dehydration. In addition, your body makes more mucus during a fever, which can lead to more fluid loss.
“The key is to drink plenty of water, juice and/or soup. Drinking water during a fever can also help promote healthy bowel functioning and speed up the process of flushing the virus or bacteria out of the body.”