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Fever

Your temperature usually refers to core body temperature, not the temperature of your skin or any external part of the body.

Let's start by defining what a normal core body temperature is, which is usually between 36°C and 36.8°C. It does fluctuate over the day and over longer periods due to the circadian rhythm, menstrual cycle and other cyclical regulatory systems. Air temperature, humidity, other environmental factors and activity levels also play a part.

A mild fever is usually considered a core body temperature at or above 38°C/100.4°F but less than 39°C/102.2°F.

A high fever is a temperature at or above 39°C/102.2°F but less than 40°C/104°F.

A very high/severe fever is a temperature at or above 40°C/104°F.

Direct cell death can occur at temperatures nearing 41°C/105.8°F so as you can imagine, your body's regulatory system's reaction, designed to return you to homeostasis (it's state of optimal functioning) and maintain life, is fast and can be significant.

Can be caused by infections such as; - common cold - influenza - COVID-19 - malaria - meningitis - appendicitis

Other causes can include but are not limited to; - medicine side effects - deep veil thrombosis - vaccination - cancer

Treatment

Assuming a fever is caused by infection, treatment is not medically necessary except where someone; is under three months old, has a compromised immune system or has other significant medical issues. However, treatment of the pain and inflammation is usually welcome.

Both paracetamol (aka acetaminophen and Tylenol) or ibuprofen (aka Advil and Nurofen) can help with these symptoms.1 Please read the linked articles for each drug before giving either to a child.

I prefer paracetamol over ibuprofen as the latter has far more side effects and risks (including gastrointestinal bleeding & kidney failure with long term use, worsening asthma at high doses and harm in later pregnancy).

Additional Symptoms & Risks

Meningitis

Raised temperature, plus; - severe headache - stiff neck - sensitivity to light

Sepsis

????

Further Reading

References

  1. High temperature (fever) in adults - retrieved 2025-09-19 ↩