6 Reasons You Don't Sweat When You Exercise

Not sweating during a workout could signal something as simple as not pushing yourself hard enough, but it could also be a sign of a potentially serious medical condition or medication side effect.

Lack of sweating is called anhidrosis or hypohyrosis, says Eric Ascher, DO, a family physician with Lenox Hill Hospital in New York City. Mild cases on just one part of your body may not even be noticeable, while extreme cases can be life-threatening.

"Without sweating, your body cannot reach a stable temperature and has the potential to overheat," explains Dr. Ascher. "In some situations, this can lead to heat exhaustion, heatstroke and possibly death if prolonged."

Here are some reasons why you may not sweat during exercise.

If you're only pedaling 2 miles an hour on that stationary bike, you shouldn't be surprised if you're not sweating. Ditto if you're not sweating during weight-training, especially if you're not reaching for weights that challenge you.

"Amount of exertion directly effects metabolic rate, heart rate, heat generation and amount of sweat generated," says Heidi Prather, MD, a board-certified dermatologist with Westlake Dermatology in Austin, Texas. "Activity leads to sweating. More activity, more sweating."

The sweat on your skin evaporating is what cools down your body.

While not sweating at all is unusual and dangerous, bear in mind that some people tend to sweat more than others even when doing the same activity, says Dr. Ascher. Larger people tend to perspire more profusely, as do people assigned male at birth.

Most people sweat more in warm, humid environments and less in cold, dry environments. "This has to do with the physics of the environmental temperature exceeding body temperature," explains Dr. Prather.

Not sweating during a workout in Minnesota in February is less of a concern than not sweating under an August sun in Florida.

Dehydration is a common cause of not sweating or not sweating enough during a workout, especially during the summer.

"This occurs when you don't have enough water in your body to carry on normal functions," explains Dr. Ascher. "You can easily become dehydrated when you work or exercise in hot weather and don't drink enough fluids to replace what you've lost through perspiration."

Persistent vomiting and diarrhea can also dehydrate you, as can taking diuretics.

"Signs of dehydration include thirst, weakness and confusion," says Dr. Ascher. "Severe dehydration can be fatal, particularly in older adults and children."

Make sure you drink enough fluid before, during and after exercising.

In addition to diuretics, many other medications can cause dehydration, including those commonly used for blood pressure, allergies, pain and mood, Dr. Ascher says.

Some examples include:

• Morphine and other opioid pain relievers
• Botulinum toxin type A (to treat muscular spasms and other issues)
• Anticholinergic drugs (used to treat a variety of disorders, including Parkinson's, urinary incontinence and heart disease)
• Tricyclic antidepressants
• Certain antipsychotics
• Certain anti-epileptic drugs like Topamax (topiramate)
• Certain high blood pressure drugs

Skin burns (including from radiation therapy), injuries, infections and even a bug bite can lead to anhidrosis during exercise, as can diseases that clog your pores, such as psoriasis.

Your body has some 2.6 million eccrine sweat glands on every part of your skin. When your body starts to heat up (from exercise or for another reason), the autonomic nervous system tells these glands to start perspiring.

Conditions that affect the skin can affect the sweat glands and your ability to perspire.

Because the autonomic nervous system controls the sweat response, diseases that damage nerves — like diabetes, alcoholism, Guillain-Barre and Horner's syndrome — can cause anhidrosis.

Other diseases that can cause anhidrosis include:

• Thyroid disease: "This is where your body cannot produce the correct amount of thyroid hormone to help regulate body temperature," says Dr. Ascher
• Certain autoimmune and connective tissue diseases, such as Sjogren's disease or lupus
• Inherited conditions such as Fabry disease, which affects your metabolic system
• Central nervous system disorders such as Parkinson's disease and stroke

Folks who have limited anhidrosis aren't likely to have any issues as long as they follow good workout guidelines, Dr. Prather says.

​1. Stay hydrated:​ Proper hydration is critical whenever and wherever you are working out and whether or not you have anhidrosis. Make sure you have water or a sports drink for before, during and after activity.

​2. Choose your activity and clothing wisely:​ Mild anhidrosis without an obvious cause can be managed by "avoiding activities that put you at risk for being unable to cool your body down and wearing loose-fitted, lightweight clothing," Dr. Ascher says.

​3. Avoid prolonged time in the direct sun or heat:​ Opt for temperature-controlled (i.e. indoor) workouts when possible. And if you're exercising outdoors, keep your workout short, especially if it's hot out.

​4. Avoid things that dehydrate you:​ It's also a good idea to avoid extreme temperatures and drug use while moderating your alcohol intake.

If you have anhidrosis over a larger part of your body, you'll need to take extra precautions and maybe even avoid strenuous activity entirely. Your first step is to work with a doctor to determine a cause and see if that can be treated.

"Sweating is a really important part of safety, especially if you live in a hot climate or are a very active individual," Dr. Prather says. "Be alert to body temperature."

It's time to see a doctor if you notice any changes in how your body sweats, especially if you're not sweating even when you're getting a really good workout.

You should also see a doctor if you have symptoms of heatstroke, which is when your body reaches temperatures of 103 degrees Fahrenheit or higher. In addition to a high body temperature, signs can include hot, red or dry skin, confusion and loss of consciousness. Seek medical care immediately at the first sign of heatstroke.

While you wait for medical help, seek cool temperatures in the form of air conditioning or cold water, Dr. Ascher says. Cooling down quickly can be life-saving.