Body Temperature

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.

So that's what normal looks like, let's take a look at what's outside the normal range.

High Temperature - Fever & Hyperthermia

A fever refers to a high core body temperature that is the result of processes within the body (in a response to infection or something similar).

Hyperthermia refers to a high temperature caused by factors outside the body, such as prolonged sun exposure, prolonged exposure to extremely high ambient temperatures or sauna bathing.

In either case, dehydration or alcohol consumption, if it occurs, is a significant risk.

Degrees of fever severity are as follows;

A mild fever is usually considered a temperature at or above 38°C/100.4°F but less than 39°C/102.2°F.¹
A moderate/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 core body 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. You, in turn, should react appropriately.

Low Temperature - Hypothermia

Hypothermia refers to a low core body temperature below 35°C/95°F.

As with fever and hyperthermia, the causes can be internal or external to the body; - internal: alcohol intoxication, dehydration, substance abuse, sepsis, hypothyroidism, anorexia nervosa, low blood sugar, anorexia and/or advanced age² ³ - external: prolonged exposure to extremely low ambient temperatures or prolonged cold water immersion and major trauma²

A water temperature of 10°C/50°F can lead to death in as little as one hour and water temperatures near freezing can cause death in as little as 15 minutes.⁴

Degrees of severity are as considered to be mild, moderate and severe.

Symptoms

Mild;

shivering
high blood pressure
fast heart rate
fast respiratory rate
blood vessel contraction
increased urine production
mental confusion
liver dysfunction

Moderate;

amnesia
confusion
slurred speech
decreased reflexes
loss of fine motor skills

Severe;

heart rate decreases
respiratory rate decreases
blood pressure decreases

Taking Your Temperature

Avoid using;

an infrared thermometer - these are rarely accurate enough to meet medical or even consumer/trading standards
forehead strips - these are simply not accurate and do not measure your core body temperature

Additional Symptoms & Risks

Sepsis

High or low temperature alone or in combination with;

a fast heartbeat/heart rate
chills & shivering
vomiting
headache
issues or changes to breathing
feeling unwell

Meningitis

High temperature in combination with;

severe headache
stiff neck
sensitivity to light