A low body temperature is generally any reading below 97°F (36.1°C) when taken orally, though it doesn’t become a medical emergency until it drops to 95°F (35°C) or lower, which is the clinical threshold for hypothermia. The old standard of 98.6°F as “normal” is outdated. Recent research shows that average body temperature actually ranges from about 95.4°F to 99.3°F depending on the person, time of day, and how the reading is taken.
What Counts as Normal Now
The 98.6°F benchmark was established over 150 years ago, and human bodies have changed since then. Studies confirm that average body temperature has been declining over many decades, and most people run slightly cooler than that old number. A reading of 97.5°F or even 97°F can be perfectly normal for you, especially if you consistently measure in that range.
Your reading also depends on where you measure. A rectal temperature runs about 0.5 to 1°F higher than an oral one, while an armpit (axillary) reading runs 0.5 to 1°F lower. So if you take your temperature under your arm and get 97°F, your actual core temperature is closer to 97.5°F or 98°F. That’s solidly normal.
Age Changes Your Baseline
Older adults naturally run cooler. The typical body temperature range for people over 65 is 96.4°F to 98.5°F, according to Cleveland Clinic data. This means a reading of 96.5°F in a 70-year-old isn’t alarming on its own, while the same reading in a younger adult might warrant more attention. The flip side of this lower baseline is that older adults can be closer to hypothermia territory without realizing it, and a fever in an older person may not register as dramatically on the thermometer.
Children tend to run slightly warmer, with a normal core range of 98°F to 99°F. In babies, a temperature below 95°F is a red flag. Infants with dangerously low temperatures may have bright red, cold skin and very low energy rather than shivering, which makes it harder to spot.
When a Low Reading Signals a Problem
A single low reading on a home thermometer, especially from an armpit or forehead scanner, is usually nothing to worry about. These methods are less precise, and factors like cold hands, recent eating or drinking, or sitting near a fan can throw the number off. If you feel fine, try again in 15 to 20 minutes with an oral thermometer.
A consistently low temperature paired with symptoms is different. Watch for fatigue that doesn’t improve with rest, feeling cold when others around you are comfortable, sluggish thinking, or slow movements. These can point to an underlying issue like an underactive thyroid, which lowers body temperature by reducing oxygen consumption and overall heat production. Infections, including serious ones like sepsis, can also paradoxically cause low body temperature rather than a fever, particularly in older adults or people with weakened immune systems.
Hypothermia: The Danger Zone
Once core temperature falls to 95°F or below, you’re in hypothermia, which is a medical emergency. It progresses in stages:
- Mild (90°F to 95°F): Shivering, fumbling hands, difficulty with coordination, and slurred speech. You’re still alert but your body is struggling to generate enough heat.
- Moderate (82°F to 90°F): Shivering may actually stop, which is a bad sign. Confusion worsens, drowsiness sets in, and breathing slows.
- Severe (below 82°F): The person may be unconscious, and their pulse and breathing can become so faint they seem absent.
The CDC advises calling emergency services immediately for anyone with a temperature below 95°F. If the person has stopped breathing or has no detectable pulse, begin CPR while waiting for help.
Cold Water Drops Temperature Fast
Environmental exposure is the most common cause of hypothermia, and water is far more dangerous than air. Water conducts heat away from the body about 24 times faster than air does. In U.S. Army research, immersion in 50°F water caused core temperature to plummet far more quickly than exposure to 32°F air, even though the air was colder. This is why falling into cold water is an emergency even in temperatures that would be manageable on land. Your body can only maintain its core temperature in water that’s close to 95°F, which is warmer than most natural bodies of water, even in summer.
Medical Causes of Low Body Temperature
Beyond cold exposure, several conditions can keep your temperature chronically low. An underactive thyroid is one of the most common. The thyroid gland controls your metabolic rate, and when it slows down, your body produces less heat. People with severe, untreated hypothyroidism can have resting temperatures well below normal without being in a cold environment.
Certain medications also interfere with your body’s temperature regulation. Antipsychotic medications, particularly risperidone, olanzapine, and quetiapine, are among the most commonly reported causes of drug-related low body temperature. Mood stabilizers like valproic acid carry a similar risk, and benzodiazepines (commonly prescribed for anxiety) can lower temperature at higher doses. Adrenal insufficiency and damage to the pituitary gland or hypothalamus, the brain’s thermostat, can also disrupt the body’s ability to maintain warmth.
Alcohol is another factor. It dilates blood vessels near the skin, which makes you feel warmer while actually accelerating heat loss from your core. Combined with impaired judgment about when to get out of the cold, this makes alcohol a significant contributor to hypothermia cases.
What to Do About a Low Reading
If your temperature is between 95°F and 97°F and you feel fine, it’s likely just your personal baseline or a measurement quirk. Track it over a few days at the same time using the same method. If it’s consistently below 97°F and you’re also dealing with fatigue, dry skin, weight gain, or feeling cold all the time, a thyroid check is a reasonable next step.
If someone’s temperature is at or below 95°F, move them to a warm area, remove any wet clothing, and cover them with blankets, focusing on the head and torso. Warm beverages help if the person is alert enough to drink safely. Avoid direct heat sources like heating pads or hot water, which can cause burns or dangerous heart rhythm changes when applied to very cold skin. For any reading below 95°F with confusion, severe shivering, or loss of coordination, treat it as an emergency.