What Body Temperature Really Says About Your Health

Have we gotten it wrong for all these years? The notion of a single “normal” number appears to be a myth.

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Your “normal” body temperature may not be as normal as you think.

The often cited 98.6 F (37 C) benchmark was established nearly two centuries ago, yet recent research reveals our inner thermometers actually fluctuate based on a variety of factors.

From your age and sex to the time of day and where you call home, the numbers on the thermometer tell a more nuanced story than “regular” or “fever” suggests, and they may be a sign of untreated and potentially serious health problems.

‘Normal’ Body Temp ‘Rarely’ as High as We Think

Between 2008 and 2017, scientists at Stanford University analyzed the oral temperatures of more than 126,000 patients seen at Stanford Health Care. They also recorded information about each patient, such as height, weight, sex, age, and the time of day their temperatures were taken.

The findings, published in September in the Journal of the American Medical Association (JAMA) Internal Medicine, revealed that the average human body temperature is about 97.9 F, almost one full degree cooler than the long-accepted “normal” of 98.6. But does this mean human body temperatures have decreased since the 19th century? Perhaps not.

When Carl Reinhold August Wunderlich, a German physician and medical professor known for setting the upper limit of normal body temperature, collected over a million temperature measurements from about 25,000 patients in the mid-1800s, he reported a range of temperatures. He also noted that men and older people showed lower temperatures than women and young adults and that temperatures trended higher later in the day. It was just the 98.6 F average that became ingrained as our standard “normal” reading.

For those interested in how body temperature can vary throughout the day, the research team has created an online, personalized temperature range calculator based on the scientists’ recent findings.

Oral Temperature Often Less Accurate: Expert

Oral temperature measurements are often less accurate than core temperature readings, typically being lower, Dr. Christopher Calandrella, chair of emergency medicine at Northwell Long Island Jewish Forest Hills in Queens, New York, told The Epoch Times.

“If a clinician is suspecting a fever, but one is not registering orally, then checking the core temperature is often the next step,” he said. “It is also worth noting that when examining a patient for a possible infection, clinicians do not rely on temperature alone.”

Doctors also consider the self-reported history of fevers or chills, if the skin is warm to touch, and if the patient has a flushed appearance, “along with other symptoms suggestive of infection,” Dr. Calandrella added.

Interestingly, a lower-than-normal body temperature—much like a fever—may also indicate potentially serious health issues.

Low Body Temperature Linked to Unexpected Health Problems

A lower-than-normal body temperature, known medically as hypothermia, can be more than just a result of prolonged cold exposure. It may also quietly signal certain underlying health conditions. Hypothermia is a body temperature below 95 F (35 C) and can have potentially severe consequences for health.

Specifically, an unexplained drop in your typical body heat could potentially indicate the following six diseases:

1. Hypothyroidism

A common cause of persistently low body temperature is an underactive thyroid gland. The thyroid gland produces hormones that regulate metabolism and body temperature. An underactive thyroid gland slows metabolism and inhibits hormone production, often leading to a below-average body temperature. Other hypothyroidism symptoms include fatigue, weight gain, and hair loss.

2. Serious Infections

Infections like sepsis or urinary tract infections can cause a drop in body temperature. In severe cases, when the body fails to fight off the infection effectively, it can lead to an abnormal decrease in body temperature. These infections require prompt medical attention to prevent further complications.

3. Poorly Controlled Diabetes

Unmanaged diabetes can trigger diabetic ketoacidosis—when there isn’t enough insulin in the body, resulting in excess blood acids—causing body temperature to decrease. Nerve damage from diabetes (neuropathy) may also contribute to feeling colder.

4. Hypoglycemia

Low blood sugar (hypoglycemia) may cause shivering and temperature drops due to insulin misdosage, missed meals, or improper medication management.

5. Addison’s Disease

With Addison’s disease, the adrenal glands do not make enough cortisol and aldosterone—hormones that regulate metabolism, blood pressure, and body heat. A lower temperature is one of the symptoms associated with this rare condition.

6. Anemia

Anemia, or insufficient red blood cells/hemoglobin, impairs oxygen circulation. The resulting tissue oxygen deprivation can manifest as a low body temperature.

It is crucial to consult a medical professional if you consistently experience a low body temperature accompanied by other concerning symptoms. Thorough evaluation and testing can determine if an underlying medical issue needs to be addressed.