11 Fascinating Facts About Body Temperature

The average normal body temperature is generally considered to be 98.6 degrees F, according to MedlinePlus. But “normal” body temperature can range from 97 degrees F to 99 degrees F, and what’s normal for you may be a little higher or lower than the average body temperature.

Your body is always adapting its temperature in response to environmental conditions, per research. For example, your body temperature increases when you exercise. And if you check your temperature with a thermometer, you will see that it’s higher in the late afternoon and evening than first thing in the morning, according to the Mayo Clinic.

Babies and young children have a higher body temperature than older kids and adults because the surface area of their bodies is larger relative to their weight, and their metabolism is more active. Newborns typically have an average body temperature of 99.5 degrees F.

A fever is a temporary increase in your body temperature, and it’s often caused by illness. A rectal, ear, or temporal artery (forehead) temperature of 100.4 degrees or higher generally indicates a fever, according to the Mayo Clinic. Fevers usually subside within a few days. If you have a fever, you may also experience the following symptoms:

• Chills and shivering
• Sweating
• Headache
• Muscle aches
• Loss of appetite
• Irritability
• Dehydration
• General weakness

For adults, a body temperature of 103 degrees F or higher can be a cause for concern and warrants a call to your doctor, according to the Mayo Clinic. Also call your doctor if, along with a fever, you have a severe headache, an unusual skin rash, unusual sensitivity to bright light, stiff neck and pain when you bend your head forward, mental confusion, persistent vomiting, difficulty breathing or chest pain, abdominal pain or pain when urinating, or convulsions or seizures.

For infants and toddlers, a temperature that is only slightly higher than usual could be a sign of a serious infection, according to the Mayo Clinic. Call your doctor if your child is age 3 months or younger and has a rectal temperature of 100.4 degrees F or higher; between ages 3 and 6 months and has a rectal temperature up to 102 degrees F and seems atypically irritable, lethargic, or uncomfortable, or has a temperature higher than 102 degrees F; or between ages 6 and 24 months and has a rectal temperature higher than 102 degrees F that lasts longer than one day.

If your child is age 2 or older, call your doctor if the fever lasts longer than three days or if your child is generally getting worse, unusually less active, or is drinking and urinating less frequently.

Young children ages 6 months to 5 years might have febrile seizures with a high body temperature, which usually involve loss of consciousness and shaking of limbs on both sides of the body, according to the Mayo Clinic. Call for emergency medical care if a seizure lasts longer than five minutes or if the seizure is associated with vomiting, a stiff neck, excessive sleepiness, or difficulty breathing. Always take your child to the doctor as soon as possible after their first seizure to figure out what caused it.

Most people fret over a fever, but it actually can be helpful. Various over-the-counter medications can lower a fever, such as acetaminophen (Tylenol) or ibuprofen (Advil), but sometimes it’s better left untreated, according to the Mayo Clinic. This is because fever seems to play an important role in helping your body fight off infections. Still, your doctor may prescribe an antibiotic if he or she suspects a bacterial infection, such as pneumonia or strep throat.

Fever is one of the symptoms of COVID-19, the illness caused by the novel coronavirus SARS-CoV-2, according to the Centers for Disease Control and Prevention (CDC). Low body temperature is not a symptom of COVID-19.

If you think you may have been exposed to this virus, the CDC recommends that you take your temperature twice daily to see if you have a fever. The CDC defines a fever as 100.4 degrees F or higher. If you have a child between ages 6 months and 4 years, use an ear thermometer to take their temperature or place a regular thermometer under your child’s arm in the center of their armpit, the CDC recommends. If your child’s armpit temperature is 99.4 degrees F or higher, they have a fever.

If it seems like you’re always cold, even during the dog days of summer, it could be your age. Research has shown that as we age, our average body temperature declines slightly. One study measured the body temperature of 133 nursing home residents found that body temperature was below average in those ages 65 to 74, even lower in people ages 75 to 84, and lowest among those ages 85 and older, some of whom had a low body temperature of 93.5 degrees F under normal circumstances. This is important to know, because seniors may actually be running a fever at lower temperatures than younger adults.

There really might be something to the saying “cold hands, warm heart.” In one study, researchers found that women’s core body temperature is, on average, 0.4 degrees higher than men’s (97.8 vs. 97.4). But women’s hands are 2.8 degrees F colder than men’s on average — 87.2 degrees F, compared with 90 degrees F for men.

Remember your mom telling you to wear a hat when it’s cold outside because most body heat is lost through your head? It turns out that her advice may not have been completely spot-on, according to one article. Studies have shown that there is nothing unique about your head when it comes to heat loss — any part of your body that is not covered loses heat and will reduce your core body temperature proportionally.

Fibbing won’t cause your nose to grow, but it will make it colder. Despite this discrepancy with the old children’s story, researchers dubbed their findings the “Pinocchio effect.” They used thermal imaging to demonstrate that the anxiety brought on by a lie causes the temperatures of the nose and the areas around the forehead to increase.

Like your food spicy? It may raise your body temperature — and your metabolism. One study had participants add about 1 gram (g) of red pepper to their food. Their core body temperature rose, but their skin temperature was lower. The study’s authors theorized that this increased heat production along with decreased sensations of appetite demonstrated a potential benefit of consuming red pepper for those who are trying to manage their weight, especially for people who don’t usually eat spicy foods.

Therapeutic hypothermia is a type of treatment sometimes used for people who have cardiac arrest (when the heart suddenly stops beating), according to Johns Hopkins Medicine. Once the heart starts beating again, healthcare providers use cooling devices to lower the patient’s body temperature to around 89 to 93 degrees F. Lowering the body temperature right after cardiac arrest can reduce damage to the brain and raises the chances that the person will recover.

This isn’t just crime-show fodder. After people die, they no longer produce body heat, and the body slowly cools, according to research. This process is called algor mortis (Latin for “the coldness of death”). Algor mortis has been used as a tool in forensic investigations to estimate how long a person has been deceased after their body has been discovered. But various factors affect body temperature, so it’s not a totally reliable or accurate technique.