Anhidrosis or hypohidrosis: the inability to sweat

Anhidrosis is a condition in which you are unable to sweat. A similar condition, called hypohidrosis, is when you don’t sweat enough. Anhidrosis can affect all or part of your body; no one knows how many people have this condition because not everyone with anhidrosis has dramatic symptoms. People may not tell their provider about it because they may not notice that they aren’t sweating or may not realize that not sweating is abnormal (Cheshire, 2016).

Sweating is a necessary response to an increase in body temperature; common sweating triggers are warm temperatures, physical exertion, or situations that make you angry, embarrassed, nervous, or afraid. When your body temperature rises, it triggers your autonomic nervous system (sympathetic nerves) to help you cool off. Once the sweat reaches your skin, it evaporates and cools you down. If you are unable to sweat to cool yourself off, you are at risk for overheating (hyperthermia), especially in high temperatures or with vigorous exercise. Conditions associated with hyperthermia include heat cramps, heat exhaustion, and heat stroke (a life-threatening condition).

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The symptoms of anhidrosis include:

• No sweating or only a small amount of sweating

• Feeling hot (because you are unable to cool down)

• Flushing

• Dizziness

• Muscle cramps

• Muscle weakness

People who have anhidrosis only in certain areas may notice that other parts of their body have increased sweating; this is to compensate for the lack of sweating in the affected areas. In other words, you may have parts of your body that are wet with sweat and others that are dry at the same time.

In anhidrosis, your sweat glands do not work as they should; this problem may start in childhood or become an issue later in life. Several factors can cause anhidrosis, including:

• Congenital diseases: You may be born with a condition that prevents healthy development of sweat glands, resulting in the inability to sweat; one example is a condition called hypohidrotic ectodermal dysplasia (Fete, 2019).

• Metabolic disorders: You may be born with a condition that affects your metabolism and ability to sweat; one example is Fabry’s disease, in which abnormal fat compounds are produced and prevent sweat glands from functioning correctly (Lidove, 2006).

• Nerve damage: Conditions that affect the health of the nerves in your skin can also decrease your sweat production; examples include diabetes, multiple sclerosis, Guillain-Barre syndrome, spinal cord transections, Ross syndrome (a rare condition that causes anhidrosis, poor reflexes, and pupils that don’t dilate properly), and Sjogren’s syndrome (an auto-immune disorder that causes dry skin and mouth) (Cheshire, 2016).

• Skin damage/disease: Burns or radiation to the skin can damage the sweat gland and cause decreased sweating. Also, skin conditions like psoriasis and atopic dermatitis can lead to anhidrosis due to skin pore problems (Tay, 2014).

• Idiopathic: In some cases, no underlying cause for the anhidrosis is found, and this is called chronic idiopathic anhidrosis or acquired idiopathic anhidrosis; most of the reported cases of this condition are in young Asian men (Tay, 2014).

People with any of the conditions mentioned above are at risk of developing anhidrosis. Also, children are less able to regulate their body temperature as compared to adults and are therefore more susceptible to hyperthermia in cases of decreased sweating. People with diabetes, since they are at risk for developing peripheral nerve damage, are also at an increased risk of having anhidrosis. Anyone taking any of the classes of medications discussed is at risk for decreased sweating.

Anhidrosis is generally not something that is observed easily in the office, mainly as it may only involve parts of the body. There are several tests that your provider may use to diagnose anhidrosis (Cheshire, 2016).

• Sympathetic skin response (SSR): This measures the electrical potential in the skin; abnormal results may indicate a decreased ability to sweat.

• Thermoregulatory sweat test: The skin is coated with a powder that changes color when it comes in contact with sweat (changes from yellow to dark blue/purple); you are placed in a warm room to encourage sweating.

• Quantitative sudomotor axon reflex test (QSART): Electrodes with acetylcholine stimulate the skin and the sweat glands; the resulting sweat droplets are collected and measured. This test can check for peripheral nerve causes of anhidrosis.

• Silastic sweat imprint test: Electrodes stimulate the skin, and pilocarpine is given to stimulate the sweat glands. As droplets of sweat appear, they create an imprint in the silastic impression material.

• Skin biopsy: A small piece of skin tissue is removed and evaluated under the microscope to determine if there are problems with the nerves in the skin or sweat glands.

If your anhidrosis only affects a small part of the body, you may not need treatment. Depending on the cause of your anhidrosis, treating the underlying condition may improve your ability to sweat normally; similarly, if it is a side effect of a medication, switching to an alternative drug can help. People with anhidrosis should avoid overheating by staying in cool environments, especially when exercising and wear loose, breathable clothing. If you think you might be overheating (hyperthermia), try to cool off by going into a cool area and/or applying ice packs or cool water to your forehead, neck, underarms, and groin. Heatstroke, the most severe form of hyperthermia, is a medical emergency and requires prompt treatment to prevent life-threatening consequences.

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Current version

January 10, 2020

Written by

Chimene Richa, MD

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.