Not everyone has the "standard" body temperature of 98.6 degrees Fahrenheit. Your temperature may run a little higher or lower than this normally, and a slightly lower than normal temperature is generally nothing to worry about. Sometimes, a low body temperature is caused by one of many medical conditions -- the list is too long to mention, but it includes such possibilities as an underactive thyroid gland, medication side effects, and a severe infection called sepsis. Your doctor will generally look at the big picture of your symptoms to make a diagnosis. A very low body temperature, or hypothermia, is defined as a core body temperature less than 95 degrees Fahrenheit, and it has many causes.
Your body temperature reflects a balance between how much heat your body makes and how much it loses. So naturally, if you are exposed to extreme cold, your body temperature may drop, and hypothermia can set in. If the hypothermia becomes severe, it can be potentially life-threatening. Serious cases of hypothermia are more likely to occur in extreme conditions -- such as if your car breaks down in a blizzard -- than if you spend a few hours bundled up at a football game on a snowy day. If you do plan to spend time in the cold, drinking alcohol can be particularly dangerous because alcohol can cause your blood vessels to expand and deliver more blood to the surface of your body where heat can be lost.
A variety of hormonal disorders can make your body temperature drop. For instance, your thyroid gland in your neck, your pituitary gland in your brain, and your two adrenal glands that sit on top of your kidneys make very important hormones that regulate many bodily functions. If any of these glands fails to produce hormones normally, your body temperature could fall. Sometimes a low body temperature may be your doctor's first clue that there is a hormonal problem.
Nervous system problems can cause a low body temperature. If you have ever had a stroke, you may notice that your body temperature is lower than it once was. Parkinson's disease and multiple sclerosis can also impact the body's delicate balance between heat production and heat loss and make your temperature drop. A ruptured brain aneurysm is another nervous system condition that has the potential to cause your temperature to be lower than usual. Brain trauma can also lower your body temperature. Your body temperature is regulated in an area of the brain called the hypothalamus, and any disorder that impacts this delicate tissue can also impact its delicate functions.
Many medications have a potential side effect of hypothermia, including medications that treat depression, anxiety and pain. If you have a severe infection, called sepsis, your body temperature can drop, though you will likely have other signs of infection that you notice before you realize your body temperature is low. Sepsis is a potentially life-threatening emergency, and if you have signs of infection along with a low body temperature, you should seek medical attention immediately. Declining kidney function has also been shown to cause a drop in body temperature in some, but not all, people.