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

Normal body temperature can vary slightly from person to person. [Credit:Xavi Sanchez]
By | Posted January 2, 2008
Posted in: Ever Wondered?, Health
Tags: , ,

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.

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  1. Why do people keep complaining here when nobody is answering? I have fibromuscular dysplasia and there’s no cure. I was just wondering if a circulatory problem was causing a low temp reading. I Have multiple brain aneurysms…already know I’m dying…oh well.

    Jene, November 21, 2012 at 6:25 am
  2. Why am do i always feel so hot? My siblings and mother always said i radiated heat ever since i was a child. Im 18 years old and im a female. Im not overweight. Diabetes, high blood pressure, chrones, and graves disease run in the family. But im the only one who is always hot. Can anyone enlighten me please?

    Anna, December 18, 2012 at 11:49 pm
  3. Hi ever since I was a child my temp has been constant 87 degrees ive always been healtyh n athletic tho I’m 21 now nothing has changed I have a strong immune system and only catch 1 virus a year on average I also heal pretty quickly Wat do u think?

    rolo, January 26, 2013 at 12:28 am
  4. If you look on the Internet for Hypothyroidism you will find signs of low body temperature. Generally, the average temperature of an adult with a healthy thyroid and a healthy metabolism is 98.6 degrees Fahrenheit or 37.0 degrees Celsius, and that occurs around mid-afternoon or 3 pm. So if you take your mid-afternoon temp and find it in low 98′s or even in the 97′s, you have been given a strong clue that you may be hypothyroid. And a few report their mid-afternoon temp being in the 96′s. BRRRR.
    Another temperature clue occurs first thing in the morning before you raise from your bed. Dr. Broda Barnes, a doctor who paid attention to clinical presentation and prescribed the pre-reformulated Armour, found that a healthy before-rising morning basal temp should be between 97.8 – 98.2. If it’s higher, you may be hyperthyroid, and if it’s lower, you are most likely hypothyroid. He also recommended under-the-arm temperature testing, but patients have found oral to be just as effective.

    Once you are on natural desiccated thyroid or T3-only, and are consistently raising your doses, you will see your temps climb to healthy levels with increasing feel-good symptoms to match. In many patients, reaching the average temp around 98.6 can happen before you are even on your optimal amount of desiccated thyroid or T3.

    Thyroid patients have found Mercury thermometer quite useful and accurate as compared to most digital thermometers. Yes, some digitals are definitely better than others. It’s also important to leave it under your tongue long enough, i.e. up to five minutes. A second alternative: a Geratherm, which is a liquid non-mercury thermometer. May be more accurate than digitals. Bulky.

    Along with Hypothyroidism there is slow metabolism and weight gain, feeling tired along with feeling cold. If you have these problems you should get your thyroids tested.

    Darlene, March 24, 2013 at 8:56 pm
  5. I believe some blood tests are not accurate…somewhere, I can’t remember where, so perhaps some blood expert can respond, I read a study where blood tests are performed and the readings/interpretation are supposed to be made after the blood is kept at body temperature, NOT room temperature…I have been diagnosed with MGUS..blood disease and am undergoing chemo…are my blood tests being conducted properly?

    howard schwartz, May 3, 2013 at 1:45 am
  6. I want answers to my question…??
    M 17 yrs old 5.1 height and weigh 57kg…
    wenever i check my temp on electric thermometer it shows me 98.9…???
    n wenever frnds hold me says ur body n hand is soo hot even i dnt hav fever…???
    i dnt knw y m always warm…
    i hav seen many frnds of myn in grlzzz…who r normal temp dey r nt at all warm…
    y is it soo…??wether its normal to hav same temp (98.9°) evry day…???
    i alwzz hav pimples on my face is dat bcoz of hot temp…
    even my back is filled wid pimples…:(
    i dnt lyk warm (hot) temp plzzz giv me some suggestion how to keep normal temp or cool body…..? :(

    shweta, May 17, 2013 at 12:27 pm
  7. We are all posting our questions, but there is no venue for answering. We can only “Post a Comment”. I guess we could post our opinions on each other’s maladies, or hope someone with the knowledge and bravery to diagnose over the internet would come along and indulge us?

    Shel, May 29, 2013 at 6:32 pm
  8. I am 23 years old and i was born with a heating condition and my normal body temp is a 97.6 and my body always over heats in the summer and all year round what is the cause of this i ha ve been trying to find out what has been causing it all my life and no one has been able to tell me and because of this condition i have had atleast 10 heat stokes in the course of 8 years and it seems like my condition is getting worse

    Wallace Schwartz Jr, June 23, 2013 at 1:43 am
  9. I have always had a lower body temp. I have had all the tests for thyroid, anemia, etc and they came out fine. When I was a kid I had a bad flu. My mother took my temperature and it read, 101, which really meant I had the equivalent of a 103 fever since my normal body temperature is around 96. That is why I started having feverish hallucinations! Over the years that reaction was consistent, anytime my temp reached over 101 I would be having the same problem. It took a while for my parent to realize what the issue was. It’s really important that doctors and nurses be aware of this. When I do go to the doctor when I’m sick, I’m reporting to them that I have a fever, but they rely on that “average” as if it’s supposed to be the same for everyone and then they tell me it’s impossible I have a fever because my temperature is reading 98, not recognizing that I’m there at the doctors because I’m sick with a fever-who goes when they are well after all! My greatest concern is god forbid I have to go to the hospital or a nursing home, they might take my temperature and not realize I have a severe infection of fever because they don’t ask you what your base temperature is.

    C, June 24, 2013 at 11:33 pm
  10. Having read this I believed it was extremely enlightening.
    I appreciate you taking the time and effort to put this short article together.
    I once again find myself personally spending way too much time both reading and leaving comments.

    But so what, it was still worth it!

    Dawna, March 27, 2014 at 3:25 pm
  11. My average temp. is about 97 degrees.

    Right now, I have to say, “Estoy enferma” or “I am sick”. My temp is 100.2 right now, which means that to a normal person that’s 101.8.

    Oh.

    Perhaps now that’s it nearly one a.m., I should really go to bed.

    Mac, May 24, 2014 at 2:45 am
  12. I had a perforated bowel in my 30’s and ended up with a colostomy. The colostomy was reversed. I have also had a bowel obstruction. All my life I have battled Diverticuloses and have been hospitalized many times for acute Diverticulitis. I narrowly escaped two more colostomy’s.

    For a few days now, I have been spiking a low grade fever, with a slight abdominal discomfort. I always keep watch on my temp, as that could be a flare-up of Diverticulitis. I still feel feverish to-day….However I was astonished to find, my temp was 36.0. That has never happened to me before. My temp has always been my barometer for, a bowel infection. Taking my temp as I speak, my temp is 36.6. I’m all over the place. I need a new barometer of some sort, to watch for an infection in my bowel.

    Julie, June 26, 2014 at 6:02 pm
  13. My mother age around 67 years.she always ask that I feel fever in my body and whole body pain in musles.I try to visit several General Phshysian and neruo and physiotherphy doctor but I am not satisfied.No sugar no thyriod problem.I request to all of you please tell how to solve this problem.S.N.DUA-DELHI -9873366251 email -snduadelhi@gmail.com

    S.N.DUA, August 16, 2014 at 1:32 am
  14. My temp. keeps reading 97.1 or lower but im burning up on the outside it’s gotten up to 103 at times on my skin and gets when I lay down at night my body heats up so bad even with the airconditioner on I can’t even let anyone sleep next to me my body gets so hot and im only 29 years old. Can you give me a clue what could be it is or if its gonna get worse I have many many health problems for a 29 years old even had a stoke already been in a coma been a diabetic but I got that under control my thyroid is back to normal, and my gallbladder is back to normal it filled up with gallstones so bad they were going to do emergency surgery twice but I never could get a ride back ‘that hospital. I don’t know where else to turn to get an answer as to what to do about it to help it or what it could possibly be.

    SARAH CONGER, October 19, 2014 at 8:23 am
  15. My temp. keeps reading 97.1 or lower but im burning up on the outside it’s gotten up to 103 at times on my skin and gets when I lay down at night my body heats up so bad even with the airconditioner on I can’t even let anyone sleep next to me my body gets so hot and im only 29 years old. Can you give me a clue what could be it is or if its gonna get worse I have many many health problems for a 29 years old even had a stoke already been in a coma been a diabetic but I got that under control my thyroid is back to normal, and my gallbladder is back to normal it filled up with gallstones so bad they were going to do emergency surgery twice but I never could get a ride back ‘that hospital. I don’t know where else to turn to get an answer as to what to do about it to help it or what it could possibly be.

    SARAH CONGER, October 19, 2014 at 8:23 am
  16. I have a consistent body temperature of 94.7. I am 39 years old and on 125mcg Synthroid. I am doing labs every 3 months and my TSH is now 0.8. If my thyroid is being treated, my body temperature should be elevated, correct? I am always freezing cold. I turn on heaters in the summer time. My nails are purple; hands and feet like an ice box. I have never conceived in my life.

    My endocrinologist thinks in black and white. My TSH is in normal range now – her job is done. I’ve seen so many doctors – they all think the same way.

    DM, October 20, 2014 at 4:30 pm
  17. Why blood temperature is greater(38degree cel) than normal body temperature( 37degree cel)????
    Any experts please explain??

    athiframdan, November 4, 2014 at 11:03 am
  18. i am feeling cold in fact in summer also,even my blood pressure is normal at all time.what does it mean?
    mail me please with reason.

    KISHAN KUMAR, December 16, 2014 at 3:23 am
  19. My body temperature has always been quite lower than every person I know. The weird part is that I do not have any form of diabetes or any underlying medical condition. All I know is that I have asthma and very horrible farsightedness. Any ideas of what the cause of low body temperature could mean?

    Amber, January 29, 2015 at 10:46 pm
  20. I just wanted to add and my apologies if it’s been stated already. Low body temperature was an indicator for thyroid issues, they say iodine deficiencies is at the root of the issue and is a necessary for the thyroid function. If you have fibroids in your breat in would be a bid indicator that you are needing iodine.

    Nancy rivera, February 11, 2015 at 7:19 am
  21. In the book hypothyroidism 2 by Mark Starr he claims that low body temperature is only caused by thyroid issues. There is Mary Shomon who is an expert in the thyroid who’s book living with hypothyroid had great info.

    Good luck and hope this info leads you in the right direction.

    Nancy rivera, February 11, 2015 at 7:21 am
  22. My son 1 yr 5 months baby. Now him tempeture is 100.1 this is normal. Fever starting range. May i know. Pls reply me with my mail.thank u…

    parvathi, May 22, 2015 at 7:09 am
  23. i have a very low, constant temperature that hovers around the 95 mark. It has been measured at 95.5 on a few different occasions and when it’s any higher than 96 or 97 I feel abnormally warm. I am almost 18 and a female. I have been tracking my Tempeture for months on random occasions when I feel fine and also I am using my sister as a control to see if the fluctuations are occurring in the themomter. They are not. She always reads in at a relatively normal temperature. It’s recently dipped into the 94 range but my parents refuse to get it checked out. Should I be worried? My blood type is A- and I do have an enlarged kidney if that makes a difference.

    Taylor, June 15, 2015 at 12:12 am
  24. Hi.
    I am 50 years old and male.
    When I lay down my body shows signs of a fever. My skin is very very hot, I sweat a lot whilst this process is going on. My partner, if we are in bed, wakes up and as to go into the other room. I can raise the temperature in the room by 2 degrees within 45mins.Does anyone have any idea what is going on!!!???
    Many thanks

    kevin, July 16, 2015 at 5:49 pm
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