What Diseases Cause Low Body Temperature? | When To Worry

A low temperature reading can feel confusing. Many people link sickness with fever. Still, low body temperature can happen with several illnesses, and temperature readings can dip with a faulty thermometer or poor timing.

This guide lays out disease-related causes of low temperature, how clinicians sort them, and when a low reading needs urgent care. If a person is confused, hard to wake, breathing fast, or has a temperature under 95°F (35°C), get emergency care.

Low Body Temperature Basics

“Normal” is a range, not one fixed number. Your temperature shifts across the day. Where you measure it also changes the result.

When clinicians worry, they use the whole picture: the number, the trend, symptoms, and risk factors. A core body temperature below 95°F (35°C) is called hypothermia, and it can be life-threatening.

What Diseases Cause Low Body Temperature? Conditions Doctors Check

Low temperature tied to illness usually falls into a few buckets. Each bucket has its own pattern of symptoms and risks.

• Severe infection: sepsis or a bloodstream infection can bring fever or low temperature.
• Thyroid disease: low thyroid hormone slows heat production.
• Adrenal or pituitary failure: low stress hormones can drop blood pressure and temperature.
• Low blood sugar: glucose shortage can reduce heat output and mental alertness.
• Brain injury or stroke: temperature control can falter when brain circuits are hurt.
• Late-stage chronic illness: organ failure and malnutrition can lower baseline temperature.

Cold exposure can sit on top of any of these and push temperature down faster. Age, alcohol use, and certain medicines can also shift the balance.

How The Body Loses Heat During Illness

Your body makes heat through metabolism and muscle activity. It saves heat by narrowing blood vessels in the skin and by shivering. Your brain’s thermostat (the hypothalamus) coordinates those moves.

Illness can disrupt this system in three main ways: it can reduce heat production, increase heat loss, or confuse the brain’s thermostat. Many diseases hit more than one lever at once.

Endocrine And Metabolic Diseases That Lower Temperature

Hypothyroidism

Low thyroid hormone slows metabolism, so the body makes less heat. People often feel cold, slowed down, and constipated.

If low temperature shows up with fainting, slowed thinking, or a slow pulse, get urgent care. A symptom list on MedlinePlus on hypothyroidism includes trouble tolerating cold and fatigue.

Adrenal Insufficiency And Adrenal Crisis

Low cortisol can drive low blood pressure and low blood sugar, which can pull temperature down. Weakness, belly pain, nausea, and dizziness can tag along.

If vomiting, severe weakness, confusion, or collapse appears with a low temperature, treat it as an emergency.

Hypoglycemia

Low blood sugar can cause sweating, shaking, confusion, and sleepiness. It can also blunt heat production when the brain and muscles are short on fuel. People using insulin or sulfonylureas are at higher risk.

If you can check glucose, do it. Give fast carbs only if the person is awake and can swallow safely.

Pituitary Or Hypothalamus Disorders

Damage from a tumor, surgery, radiation, or head injury can disrupt hormone signals and the brain’s thermostat. Repeated low readings with new headaches, vision changes, or menstrual changes deserve evaluation.

Infections That Can Present With Low Temperature

Some infections cause fever, but some cause low temperature, especially in older adults, newborns, or people with weakened defenses. Sepsis is the most urgent infection-related cause to rule out.

MedlinePlus notes that sepsis symptoms can include fever or low body temperature (hypothermia) along with confusion and low blood pressure. The MedlinePlus Medical Encyclopedia entry on sepsis lists other signs such as rapid heartbeat and lightheadedness.

If a person has a low temperature with fast breathing, new confusion, dizziness, mottled skin, or reduced urination, treat it as an emergency. Time matters with sepsis.

Brain And Nervous System Conditions Linked To Low Temperature

Stroke Or Brain Bleed

Strokes often cause sudden weakness, drooping on one side of the face, slurred speech, or trouble walking. Some strokes can also affect temperature control, especially when deep brain regions are involved.

Traumatic Brain Injury

Head injury can disrupt the brain’s thermostat. If someone has head trauma plus a low temperature and worsening sleepiness, get emergency care.

Spinal Cord Injury

The spinal cord carries signals that tighten blood vessels and trigger shivering. When those signals are interrupted, the body may lose heat faster and struggle to warm itself. This risk is higher with injuries higher up the spine.

Quick Map Of Illness-Related Low Temperature Patterns

Circulation Problems, Shock, And Organ Failure

Low body temperature can show up when blood flow is poor. In shock, blood may be shunted away from the skin and limbs, leaving hands and feet cold. If the root cause is bleeding, heart failure, or a severe infection, temperature can fall while other danger signs rise.

Late-stage kidney disease and liver failure can also lower baseline temperature. In these states, the body struggles to balance fluids, nutrients, and metabolism. A low reading in someone who already looks ill should raise the urgency level.

Nutrition, Low Weight, And Chronic Disease

Low body fat and low muscle mass reduce heat production and heat storage. Eating disorders, cancer-related weight loss, chronic gut disease, and severe malnutrition can all push baseline temperature down. People may also get cold hands and feet, a slow pulse, and low blood pressure.

This isn’t only about calories. Low protein intake and certain vitamin deficits can affect energy, muscle function, and blood flow. When a low temperature repeats, clinicians often ask about appetite, weight trends, and digestion changes.

Medicines And Substances That Can Lower Temperature

Some drugs don’t cause low temperature on their own, but they can make it easier for temperature to fall during illness or after cold exposure. Sedatives can blunt shivering, some antipsychotics can disrupt heat control, and alcohol can increase heat loss through the skin.

If low readings started after a new prescription or a dose change, bring that list to a clinician. Don’t stop a prescribed drug on your own unless an emergency clinician tells you to.

How To Check A Low Temperature Without Getting Fooled

A single odd reading can be a device problem. Before you assume illness, recheck with a second method if you can do it safely.

• Use a reliable site: Oral readings drop if you just drank something cold. Wait 15 minutes after eating or drinking.
• Match the tool to the person: Forehead scanners can read low if skin is cold or sweaty. Ear thermometers can read low if the seal is poor or earwax blocks the sensor.
• Look for trend: Two or three readings, spaced 10–15 minutes apart, tell more than one number.
• Use symptoms as the tie-breaker: If the person is confused or hard to wake, act on the symptoms, not the gadget.

When A Low Temperature Is An Emergency

If the reading is under 95°F (35°C), treat it as urgent. The CDC calls hypothermia a medical emergency and advises getting medical attention right away when temperature is below 95°F. CDC winter guidance on hypothermia also lists warning signs like confusion, slurred speech, and drowsiness.

Mayo Clinic describes hypothermia as an emergency and notes that it can happen when the body loses heat faster than it can make it. Mayo Clinic hypothermia signs and causes adds symptom patterns that help people spot trouble early.

Red Flags And What To Do Right Now

What Clinicians Often Check For

In a clinic or ER, the first job is to confirm the temperature with an accurate method, then screen for life-threatening causes. The workup depends on age, symptoms, and medical history.

Common checks include blood sugar, electrolytes, kidney and liver tests, thyroid labs, and infection markers. If sepsis is on the table, clinicians also look for the infection source, collect blood or urine samples, and start treatment fast.

If hormone failure is suspected, clinicians may check cortisol and other pituitary hormones. For neurologic symptoms, imaging and a full exam can help sort stroke, bleed, or head injury.

Safe Steps While Waiting For Care

If the person is awake, can swallow, and is not vomiting, gentle warming can help while you arrange care. Move them away from cold air, remove wet clothing, and use dry blankets. Warm drinks can help, but avoid alcohol.

Skip hot baths, heating pads on bare skin, or hard rubbing. Those can cause burns or move cold blood from the limbs back toward the heart too fast. Aim for gradual warming and quick access to medical evaluation.

Putting It Together For Repeat Low Readings

If you keep seeing low numbers without clear cold exposure, track time of day, device used, recent food or drink, and symptoms. Bring that log and your medication list to a clinician. Repeated low temperatures can link to thyroid disease, adrenal problems, chronic infection, malnutrition, or neurologic disease.

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