Health

Why does my normal body temperature always seem to be lower than 98.6 degrees? By how much do normal human body temperatures vary?

- Asks Lev from Detroit, MI

January 2, 2008
Normal body temperature can vary slightly from person to person. [Credit:Xavi Sanchez]
Normal body temperature can vary slightly from person to person. [Credit:Xavi Sanchez]

When the German physician, Carl Wunderlich, first reported 37 degrees Celsius (or 98.6 degrees Fahrenheit) as the average human body temperature in 1861, he claimed to have drawn his conclusion from more than a million armpit measurements of 25,000 patients. As unlikely as that sounds, it’s true that “normal body temperatures” are largely based on observation, and not any comprehensive theory.

In fact, normal body temperature not only varies between individuals, but also flutters within the same person with time of day and age, usually between 96.9 °F and 100 °F.

If you measure your own temperature at different parts of the body, say in your mouth and under your arms, you’ll notice that the temperatures are different. The general rule is that the thinner a body part is, the less contact it has with the outside environment, and therefore the higher temperature you’ll observe.

As with all other mammals, humans maintain a relatively constant temperature by breaking down carbohydrates, proteins and fats for energy, much like a power plant that burns coal for energy. The process occurs inside our cells, where oxygen, water and nutrients chemically react to produce carbon dioxide, energy and heat. That heat is then absorbed by blood and distributed throughout the body via a network of veins, arteries and capillaries.

The elasticity of those capillaries plays a central role in our ability to maintain constant body temperatures. When there’s too much heat in the body, our capillaries automatically expand and increase the blood flow to the skin, allowing the excess heat to transfer to the air. This is why people become flushed after working out. Conversely, when we don’t have enough energy to balance out the heat loss, capillaries narrow to slow down the blood flow and therefore minimize energy escape.

However, not all fluctuations of our body temperature fall under the control of blood vessels. For example, you are likely to have a higher temperature right after a 100-meter sprint than when you are fast asleep. Intense physical activities temporarily boost your metabolic rate as your body burns more fuels to balance your energy consumption.

Body temperatures wax and wane with hormone levels, too. That’s why a woman’s basal body temperature, or her temperature on waking after a normal night’s sleep, is often used as an indicator of ovulation. Characterized by the surge of luteinizing hormone, a kind of hormone needed for proper reproductive function, ovulation usually increases basal body temperature by 0.4 °F to 1 °F.

Women also tend to have higher rectal body temperatures, or temperatures taken directly inside the body cavity, than men, according to a 2001 study by a group of Dutch scientists. They largely attributed the difference to women’s reproductive cycle, which may in turn explain why men and women have slightly different ways to maintain their body temperatures. Other possible explanations include different abilities to contract blood vessels and differences in resting metabolic rates.

Meanwhile, controlling body temperatures has recently emerged as a potential treatment for stroke. Clot-causing cells, the main culprit for blocking blood vessels and inducing stroke, were found to be less active at lower temperatures. The commonly accepted target temperature is now set at 91.4 °F, or 33 °C, but clinical trials are still underway in the search for optimal conditions for treatment.

While those treatments require a change in body temperature, it is generally true that a healthy person will have a fairly constant body temperature. In fact, it’s so important that your body spends 90 percent of its metabolic energy to make very sure that your temperature is as close to 98.6 °F as possible. So, even though you may feel hot or cold, or worry that your body temperature isn’t 98.6 °F all the time, rest assured, your body is working very hard to maintain that temperature.

About the Author

Jessie Jiang

Jessie has a B.S. degree in chemistry from Peking University in China, where she initially did research on molecular magnetic materials but gradually switched her interest to science writing. Before joining SHERP, she held internships as a reporter at the English-language Shanghai Daily, and at Ogilvy Communications’ Beijing office. She loves writing, and hopes to become a science editor someday as her father has been for decades.

Discussion

77 Comments

rennie boersma says:

Why am I always feeling so cold? I put on layers of clothing and even in rooms or places where others have only a t-shirts or so I seem to need at least a t-shirt and sweatshirt or sweater and even then often am cold. Also very often have cold feet. Thank you Rennie

moore says:

at 69 my temp is 96.6-i take diovan 320mg to lower my bp.since its purpose is to push circulation to extremities could this explain my low temp.

Constance Eves says:

age 77, tend to have oral temps in the 97’s. If temp goes to 98.8 or higher, I feel as if I have a fever–zlight dizzyness, ‘spacey’ feeling, a bit of balance trouble. But doc says no fever unless temp hits 100.4. Can one have a fever with a lower temp as I feel I do?

Shannon says:

I am no doctor but dont somone of your age normally run a lower BP rate anyway? That would explain why you feel this way when your is higher that usual.♥

Patricia says:

There is a lot of undiagnosed hypothyroidism out there! I had all kinds of wierd symptoms, twitching, sweating, cold, dizzy, weak and fatigued, and was told my thyroid was just fine.
Then I got worse and in an emergency room was told my thyroid was not fine, but “sometimes the problem doesn’t show up on the tests for awhile.”
I got a ton of info from a site called
stopthethyroidmadness.com. The blood tests are by no means always accurate and synthetic thyroid sucks, to sum up.

Prem P Batra says:

I am 71. I find my temperature varies between 96-97 to 98.6 to 99. I feel feverish at 98.6 with body ache, aching backbone, do not feel like taking bath etc. I feel OK when temp around 97.6/98.
Naturally I have other multiple problems eg Apical Hyperotrophy, Diastolic Dysfunction, Hypertension, 40% heart blockages, Autonomous Nervous Dysfunction more at rest, peripheral neuropathty, dymelating, cervical, lumber and bent tail bone with denegeration of Discs, sensitive to gluten!, reducing caffeine tp reduce irritation of bowels, poor ballder pump with pain, simple kidney cyst Lt, frequent urination with disturbed sleep: Surgeries done tonsils, appendix, prsotrate, both inguinal hernias, urethera strictures, and bladder neck,frequent urination catarcat surgeries, high and low sugar varying between 71 to 260 with 4hours TT but controlled with food intake at medication, no thyroid problem , no HIV, no PSA, and so on.
Medication for heart and sugar and other from time to time.

Basic irksome problem is this low grade fever?

Colleen Brown says:

My husband is suffering (for about 2 yrs. from what seems to be a malfunctioning temperature gauge. He goes from hot to cold in a mattter of minutes. Has anyone suffered from this?

Megan says:

I’d like to know also why I’m always cold. I used to have this furnace that kept me warm and it seems once I hit puberty hit, the pilot ligh went out.

kaci says:

My temperature has dropped to 97.7 most of the time. I was at the doctor and he said he gets very few patients with a temp. of 98.6 anymore. Most are running lower temps. This seems strange/ what is causing this?

Joy Hales says:

I’m in good shape and have great health, but I am constantly colder than everyone else. I wear layers or have a blanket when others are in shorts and t-shirts. Why is this?

Cally says:

I actually run quite cool for my age, I’m normally 95.6 – 96. I’ve lived in the desert all my life and I’m quite happy to wear short sleeves and shorts in 55 degree weather, but I can’t stand temps above 85 degrees (ironic to where I live). I’m just curious, does having a cooler temp then the average Joe affect my tolerance for cold or hot temperatures?

Please, please, please, could you send me a copy of this article. I have a longstanding debate with a collegiate.

miroslav says:

Can you help me find information on the individual differences in normal human body temperature circadian fluctuations. Thank you in advance. Best regards.

Gary Burdick says:

In reply to Colleen Brown,July 31st, 2008 at 5:13 pm: I am 72. My temperature varies greatly. For example, in the past two days, it has bounced up and down repeatedly between 92.6 and 99.1. It has been doing this for over four years. No medical personel seem interested. It is driving me to distraction, literally. When at low temp extremes, it is difficult to focus, to remain physically and mentally balanced. It is ruining my life.

Luke says:

@Gary Burdick:

Highly fluctuating temperatures may be a sign of an adrenal insufficiency which is also often found with hypothyroidism.

Google “adrenal insufficiency” or “hypoadrenalism” as a starting point.

Of course, there may be other things but it might be a good place to start searching.

Naomi Juyn says:

Over the years I have noticed that my body temperature is usually around 35-36 degrees. So I can be feverish without actually reaching the classic 38-39 degree temerature. This is the same for my brother and 2 sisters, as well as my mother. Could it be a genetic thing?

Alexander says:

This….doesnt look like gonna be an easy biology project to copy

Roman says:

My temperature is often around 34.7 Centigrade. I recently suffered a pulmonary embolism and I wonder if there could be a correlation with my low body temperture. Cause of embolism not been established, as there is no sign of DVT. I am very fit and lead a ‘fitness oriented lifestyle’. Any ideas?

why am i more colder in warm weather than hot

Meg Amor says:

Cold feet and generally feelng cold are often associated with low thryoid function in one form or another. Also, low adrenal function is another cause, especially the hot to cold in minutes thing. http://thyroid.about.com/ has a list of Thyroid doctors throught the word. Most of these docs will also deal with any other endo things going on, ie. Low hormones, adrenals etc. Most endo issues has a cascading effect. If one is out, then they push the other ones, like adrenals etc and they usually have to be treated as a unit. I have Hashimotos and only go to a person on these lists. Also, StoptheThyroidMadness.com is a brilliant site.

j. frentzel says:

Why is a baby’s skin temperature different than their under arm temperature, when under an infant warmer?

C. Rakes says:

I am 59 years of age, a woman, with osteoarthritis, and “onion skin.” For the past 10 years, when I’m ill enough to not work, my temperature it is always below 97F, typically 96.6F though it has dipped to 95.3. Why does this happen to me?

s. foster says:

Hi, my daughter is now 8 years old and she has always had a low temp 35 celsius. I worry about it and doctors dont do anything about it. She was a premi baby 5lb. What should I do?

Student says:

Age 18, student, For older aged people it is normal for your average body temp to drop. I read on http://www.health.harvard.edu/press_releases/normal_body_temperature and it said that which i have mentioned above. check it out for yourself! it was pretty interesing!

L Odum says:

When my daughter really feel bad thier temp runs very low. Example 96.2 and she feels bad. Her dad was the same way. They never ran 98.6. Is low temp bad?

L Odum says:

when my daughter (20 yrs old) runs fever 96.2 she is feeling bad. Her dad always ran a low grade but be sick. If thier temp went to 99 they would be very ill. Is there a problem here.

Jess says:

I have adrenal insufficiency and hypothyroidism and have a genetic tendency to chronic low grade infections. According to the environmental doctor I see this is why my temperature stays lower than normal and spikes high or very low. Low ongoing metabolic rate + recurring infections. I have found many health professionals minimize the temperature issues I have but I have found one now who is educated enough and sensitive enough to do the right tests and acknowledges the day to day difficulties associated with it. Please get good health advise. When cold, support yourself to get your temperature up, when high get it down when possible. Hormonal tests might help and protecting yourself from chemical toxicity (chemical poisoning can cause disrupted hormonal system).

Sigvaris says:

I have low body temperature and low blood pressure. I am ALWAYS cold, a lot colder than most people are. Especially my hands and feet. I always wear so many layers of clothes and I am still cold. I would love to see how all of this correlates. If the being cold, low body temperature, and low blood pressure all have something to do with each other.

JOe Schmo says:

everyone should perform more oral sex, it assists in raising your body temperature. Scientific fact, ask your doctor.

Sincerely,

Joe Schmo

Barbar Koehn says:

Iam 65 years old and am always cold. At this moment it is 80 in my office and my hands and feet are cold. I am always colder than people I know. At this writing my temperature is 95.9. As of my last blood pressure testing, it was normal. Also the latest blood test for choresterol was normal. I also had a throid blood test T3, T4 and it came back normal. I am still in menopause and have had hot flashes for the last 8 years. I am not taking any hormone medication.

NgoVan Nguyen says:

Why am I always feeling so cold? I put on layers of clothing and even in rooms or places where others have only a t-shirts or so I seem to need at least a t-shirt and sweatshirt or sweater and even then often am cold. When I get cold is easy to get sick ( flu) Also very often have cold feet. Thank you

Deby says:

I would like to know why i am always HOT .. I’ve been this way for years – at least 15. My body weight has changed during this time, but I am always hot. No diabete, been tested. Hands and feet will swell and hurt. Please, any information is welcome.

indra says:

what is the reason for different temperature in human and man

annie says:

I am 21 and just took my temperature and it was 95.1 … I am very cold. I am shivering and want to go to bed (but have lots of homework. why is my temperature so low? I feel like I should go see a doctor.

Kris says:

I thought I was going crazy- now I know it’s not that uncommon.

Teresita G.Marcaida says:

What is the reason,when the body is feeling very cold,then,after an hour feeling so,hot.then again feeling cold?i almost feeling like that,for almost
two months,So,thinking maybe it’s a symptoms of sickness?im worried about my health..

Annie says:

I’m 34 y.o. healthy female. My normal basal temp has always been 96.6-96.8 (97.2-97.3 during ovalution, usu. fluctuate less than .2-.4 through the day) since teenager years. I have a cold (or flu?) right now. My current temperature is 98.4 and I feel like crap with headache, chills, severe body ache, dry cough, sore eyes, nausea and sinus pain. This has been going on for the past three days when I often find myself in shivering chills since late afternoon/early evening everyday. When I use my own hands to touch my forehead, I feel like I’m undoutedly having a fever. But when others touch me, they think I’m fine. And I’m not feeling fine at all. Anyway, if my temp gets to 99 tonight, I’ll take Tylenol to get some relief whatever others say. You know your own body best and should trust yourself to judge whether you have a fever or not based on your feelings. And my TSH is normal – not sure what’s up with the low basal temp.

KEN POMEROY says:

IF I HAD A TEMP OF 98.6 I WOULD HAVE TO BE RUSHED TO THE HOSPITAL AS HAVING A VERY HIGH FEVER,I AM COLD MOST OF THE TIME EVEN WHEN OTHERS AROUND ME ARE VERY WARM. TO DAY I WAS CHECKED MY TEMP, WAS 93,I AM 83 AND I FEEL GREAT I GUESS I WILL END UP AS THE COLDEST CAT IN THE GRAVE YARD.

Matthias says:

MY basal temperature is lower than it should be, but on evening I have perfect body temperature. Any reason?

Marissa says:

I’m 14 and I’ve always had a temperature of 96.4. when I’m at school and I feel like I have a fever, they take my temperature and it reads 98.9 and they are like, ” Oh it’s fine” and then shove me out the door:(

john says:

What is your blood type? If type negative more likely your body temperature will be low. The problem is general medicine will not recognize the difference between
Positive and negative type and will stick you with all them symptoms …results will follow

Linda says:

Mt body temperature has been low for many years ranging from96.2 to 97.2 and my docotr has never seemed to worry about it. I find it odd to have such a low temperature since I live in Florida and it rarely gets cold here. But when it does the wind makes it even colder. I read every post and it seems like a lot of people have lower than normal budy temps. I am going to the ER today for a pain under my right ribs hopefully it is only my gallbladder. Im not looding forward to THE SURGERY BUT i WOULD BE GLAD FOR THEM TO REMOVE IT, AND HOPE THAT IS ALL IT IS. Wish me kuck and pray it isnt Cancer im 53 and lost my son in 2005 to brain cancer I prayed to God to take it all away from my son and give it to me,But that isnt how it works. Good luck to everyone,, Linda

Linda says:

I hope everyone has turned out well and it wasnt anything that couldnt be fixed. Sincerely Linda

Amanda-Beth says:

I’m 26 I’ve always ran 97.6. I know when I’m sick unfornatly drs dont alwys cause of the 98.6 or whatever thing they think nothing of it for me thats low grade fever if it hits 99 f or greater I feel pretty miserable. at 102 I often hallucinate I’ve gotten use to drs being pretty useless until temp reaches 103-104 unforntly at that point even though I may or may not be able to communicate I’m not really their. Drs really need to learn that a fever is diffrent fkr each person and adress that as it comes to better treat patients before bad things happen.

Aasish Rai says:

I am 31 yrs. old my body temperature is lower then 1 or 1.2,1.5 it fluctuates between 1 and 1.5. I also feel cold while other wear half shirts I need light sweater. Also I sweat heavy.

Varidh says:

Well there seem to be two types of people with low body temp. most of the time
1) Who feel normal/hot (not hot to touch- they are usually cold to touch) while others are feeling cold/comfirtable [I AM ONE OF THESE]
These are those whose body’s internal thermostat is set at a lower than normal
temp. so compared to the body the ambient temp. wud b relatively higher for
them than others.
2) Who feel cold while others are comfirtable
These are those whose thermostat is set normal but body is unable to bring up the temp. to the set normal due to some prob. in metab. eg. hypothyroidism

Wrtiting this comment at a temp. of 97.4 F and feeling feverish enuf to take a leave (I m a medical student) nd not do nethng

Janey Hood says:

I fixed my body temperature from 35.8C to 37C eighteen months ago.
Read my story

normalbodytemp.co.uk

Janey

Janey Hood says:

OOps I meant
normalbodytemperature.co.uk
Sorry!!
Janey

Ida says:

I want to know why a older person has low Temperature and how come its so
low for a older person and is because of heat when its hot outside hope
you can find me some anwers

Alyssa says:

I am about to turn 18 years old and my normal body temperature is about 95.1. Why is it so much lower than normal?

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