Anhidrosis (Inability to sweat)

Anhidrosis (also called HYPOhidrosis) is defined as an absence of sweating. Anhidrosis can affect small or large areas of the body and be caused by one or more of dozens of factors. No one knows exactly how many people are affected by anhidrosis. That's probably because people with mild cases of the condition may not even be aware that they have it or, if they are, they may never report it to their healthcare providers.

While hyperhidrosis sufferers may find themselves thinking that anhidrosis doesn't sound like such a bad thing, the truth is that being unable to sweat is potentially life-threatening. Sweat is essential to human survival because it serves as the body's coolant, getting rid of excess body heat (produced by your metabolism and working muscles) and protecting you from overheating. In fact, even people who don't have hyperhidrosis are constantly sweating; they just might not notice it.

Whenever your body temperature begins to increase, your autonomic nervous system stimulates your eccrine sweat glands (the average person has 2.6 million of them) to secrete fluid onto the surface of your skin. As this fluid (called perspiration or sweat) evaporates, your body starts to cool down. Under normal circumstances, a single pea-sized bead of sweat can cool nearly 1 liter (about 1 quart) of blood by 1 degree Fahrenheit.

Because they can't sweat and therefore can't cool their bodies, people with severe anhidrosis have trouble working and exercising and can be in serious danger if they attempt strenuous activity in high temperatures. Without being able to sweat, they are at high risk for heat-related illnesses such as heat exhaustion and heat stroke. In extreme cases, or if these heat-related illnesses are not treated appropriately, coma or death can result.

Anhidrosis can occur as an isolated condition or as part of a group of symptoms associated with another disease. Anhidrosis can also occur after skin has been injured because sweat glands are clogged or obstructed, as an inherited defect, or as a side effect of a medication. Given the wide range of reasons why a person may not be able to sweat, it's often difficult to pinpoint the true origin of the condition in an individual. For those people who suffer from anhidrosis on only small parts of their bodies, treatment is probably not necessary because sweat from other body areas can usually effectively compensate and keep the body cool. But for those people with large body areas affected, finding the cause of the problem is often crucial to finding a treatment.

Factors that may lead to anhidrosis include (but are not limited to):
Certain Drugs/Medications: In particular, antipsychotic medications used to treat serious mental disorders may interfere with the normal functioning of the sweat glands. Also, medications with anticholinergic properties and calcium-channel blockers may cause anhidrosis.

An Inherited Condition: It's rare, but some people are born without sweat glands. Males with hypohidrotic ectodermal dysplasia, for instance, suffer from this problem and are, therefore, at high risk of death from overheating (hyperthermia), especially in hot environments.

Nerve Damage: Injuries to the nerves that help control some of the involuntary functions of the autonomic nervous system (which regulates your internal organs, sweat glands, and blood pressure, for instance) can interfere with the activity of your sweat glands. Such nerve damage may be caused by a number of medical problems including gout, B-vitamin deficiency, diabetes, and alcoholism.

Clogged Ducts: Skin diseases and conditions that can block or clog sweat ducts (a problem called poral occlusion) are the most common causes of anhidrosis. This is, by the way, how antiperspirants work, albeit on a localized and temporary basis.

Skin Injures: Injuries to the skin and sweat glands can also cause anhidrosis. Such injuries can occur due to major third-degree burns from fire, chemicals, electricity, medication overdose, and poisonings.

Dehydration: This occurs when you don't have enough water in your body to carry on normal functions. 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. Other common causes of dehydration include persistent vomiting or diarrhea or the use of medications that increase the flow of urine (diuretics). If these problems last long enough, a person can eventually lose so much fluid that he or she is no longer able to sweat. Signs and symptoms of dehydration include thirst, weakness, and confusion. Severe dehydration can be fatal, particularly in older adults and children.

Heat Stroke: Like dehydration, heat stroke can occur when you work or exercise strenuously in hot weather and don't drink enough to replace the fluids you've lost. Heatstroke is serious because it causes your body's normal mechanisms for dealing with heat stress to shut down. Major signs of heat stroke are a high body temperature (generally greater than 104 degrees Fahrenheit/40 degrees Celsius) with hot, dry skin, confusion, and even coma. Heat stroke can be fatal.

Treatment for anhidrosis depends on the cause and, unfortunately, many cases will not be easily treated. If you develop a noticeable decrease in sweating, it's important to talk to a healthcare professional. Anhidrosis of a limited body area is usually not a problem, but anhidrosis over large portions of the body can dangerously limit your ability to keep cool. In such instances, it's important to take steps to prevent heat exhaustion, heat stroke, and dehydration until you can discuss your anhidrosis problem with a healthcare professional.

Editor's note: Our editors could not find an organization that supports the needs of anhidrosis sufferers or much information for the layperson on the condition.

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