Hypothermia: What It Is and What a Low Body Temperature Means

You measured 35.5 and are staring at the thermometer. Or you heard the word "hypothermia" and want to understand what it means. Let's go through the numbers calmly and in order.

What hypothermia is

Hypothermia is a drop in body temperature below 35 °C. Normal is about 37 °C. It is an emergency condition treated in hospital. The body loses heat faster than it produces it.

The process develops gradually and affects thinking. A person may not understand that they need help. Without help, this condition can lead to death. Cold stress is distinguished separately: the person shivers, but the temperature stays within 35–37 °C.

What body temperature is considered low

The reference point is 35 °C. Anything below that is already hypothermia. Temperature has daily and seasonal fluctuations within 0.1–0.6 °C. In women it shifts with the cycle: at ovulation it rises by 0.6–0.8 °C.

The normal 37 °C allows deviations of ±1.5 °C. Changes greater than ±2–2.5 °C mean that compensatory mechanisms have been exhausted and organ function is impaired.

What a temperature of 35.5 and 36 means

Normal is about 37 °C with deviations of ±1.5 °C; 36 and 35.5 °C are above the hypothermia threshold of 35 °C.

Core temperature is not to be confused with skin temperature. Skin varies over a wide range: it is affected by blood flow, sweat, and heat exchange.

Causes of low body temperature

Most often the cause is external: too little clothing in the cold, prolonged time outdoors, falling into cold water, wet clothing. Wind and high humidity accelerate heat loss. A cold home is also a cause — especially for older people living alone.

Infants become overcooled in a cold room. The risk is higher in young children, older people, and with exhaustion and dehydration. Less often, temperature drops due to thermoregulation disorders, trauma, or certain medications.

Symptoms and stages of hypothermia

The picture consists of several signs:

• chills;
• pale, cold, and dry skin; the lips and skin may turn blue or gray — on dark skin this is more noticeable on the palms and soles;
• slurred speech;
• slow breathing;
• lethargy or confusion.

In an infant the signs are different: cold to the touch, lethargic, unusually quiet and sleepy, may refuse to feed.

By severity, mild hypothermia is distinguished — 32–35 °C, moderate — 28–32 °C, severe — 20–28 °C, and profound — below 20 °C. At a rectal temperature of 33–32 °C, drowsiness and clouding of consciousness appear. At 30 °C and below — a drop in metabolism, decreased blood pressure, slow pulse and breathing, loss of consciousness. Below 25 °C the condition is life-threatening. The picture depends on the severity and on how long the person remains in the cold.

When to see a doctor

Suspected hypothermia is a reason not to wait at home. Such a person is examined and treated in hospital. The doctor assesses temperature, breathing, consciousness, and heart function. In the hospital, pulse is monitored, oxygen may be given, and warm fluids may be administered intravenously. Severe hypothermia requires intensive care.

Hypothermia is considered a temperature below 35 °C. If you suspect hypothermia — chills, slurred speech, slow breathing, lethargy, or confusion — medical help is needed.

103 or 112 — if you suspect hypothermia in yourself or in a child. Call immediately if confusion, slurred speech, slow breathing, or bluish or gray lips are added. Call if the person has lost consciousness. A cold-to-the-touch, lethargic infant who refuses to feed is also a reason to call an ambulance.

This material is for reference: it does not replace a doctor's consultation, but only helps you gather your thoughts before one.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer