What is anhidrosis

Anhidrosis is the inability to sweat normally ¹. An abnormal lack of sweat in response to heat may be harmful, because sweating allows heat to be released from the body.

When you don’t sweat (perspire), your body can’t cool itself, which can lead to overheating and sometimes to heatstroke — a potentially fatal condition.

Anhidrosis can be localized or generalized. Generalized anhidrosis may occur secondary to congenital absence of sweat glands (ie, anhidrotic/hypohidrotic ectodermal dysplasia), metabolic disorders (e.g. Fabry disease), and secondary anhidrosis as a result of connective tissue disease (e.g. Sjögren syndrome), chronic dermatoses by plugging of eccrine duct (e.g., psoriasis or atopic dermatitis), panautonomic neuropathy ², underlying neurologic disorders with autonomic dysfunction (e.g. multiple sclerosis or Shy–Drager syndrome), peripheral neuropathies (e.g. diabetes mellitus, Guillain Barre syndrome), and drugs (e.g. anticholinergic or psychotropic agents) or it can be idiopathic ³, ⁴.

Anhidrosis — sometimes called hypohidrosis — can be difficult to diagnose. Mild anhidrosis often goes unrecognized – until a substantial amount of heat or exertion fails to cause sweating. Dozens of factors can cause the condition, including skin trauma and certain diseases and medications. You can inherit anhidrosis or develop it later in life.

Treatment of anhidrosis involves addressing the underlying cause, if one can be found.

Symptoms of anhidrosis

Signs and symptoms of anhidrosis include:

• Little or no perspiration
• Dizziness
• Muscle cramps or weakness
• Flushing
• Feeling hot

A lack of perspiration can occur:

• Over most of your body (generalized)
• In a single area
• In scattered patches

Areas that can sweat may try to produce more perspiration, so it’s possible to sweat profusely on one part of your body and very little or not at all on another. Anhidrosis that affects a large portion of your body prevents proper cooling, so vigorous exercise, hard physical work and hot weather can cause heat cramps, heat exhaustion or even heatstroke.

Anhidrosis can develop on its own or as one of several signs and symptoms of another condition, such as diabetes or skin injury.

When to see a doctor

If you barely sweat, even when it’s hot or you’re working or exercising strenuously, talk to your doctor. Talk to your doctor if you notice you’re sweating less than usual. Because anhidrosis increases your risk of heatstroke, seek medical care if you develop signs or symptoms of a heat-related illness, such as:

• Weakness
• Nausea
• Dizziness
• Rapid heartbeat
• Goose bumps on the skin, despite warm temperatures

Anhidrosis causes

Anhidrosis occurs when your sweat glands don’t function properly, either as a result of a condition you’re born with (congenital condition) or one that affects your nerves or skin. Dehydration also can cause anhidrosis. Sometimes the cause of anhidrosis can’t be found.

Causes of anhidrosis include:

• Conditions you’re born with, such as certain congenital displasias that affect the development of sweat glands including ectodermal dysplasia
• Inherited conditions that affect your metabolic system, such as Fabry’s disease
• Connective tissue diseases, such as Sjogren’s syndrome, which causes dry eyes and mouth
• Skin damage, such as from burns or radiation therapy, or diseases that clog your pores (poral occlusion), such as psoriasis
• Conditions that cause nerve damage (neuropathy), such as diabetes and alcoholism
• Certain drugs, such as morphine and botulinum toxin type A, and those used to treat psychosis.
• Brain tumor
• Dehydration
• Nervous system disorders such as Guillain-Barre syndrome
• Skin diseases or scarring of the skin that block sweat glands
• Trauma to sweat glands
• Use of certain drugs

Risk factors for anhidrosis

Certain factors make anhidrosis more likely, including:

• Age. People age 65 and older, infants, and children are more prone to heat stress, which can contribute to anhidrosis.
• Certain health problems. Any medical condition that damages your autonomic nerves, such as diabetes, makes sweat gland problems more likely.
• Skin disorders. Many diseases that irritate or inflame the skin also affect the sweat glands. They include psoriasis; exfoliative dermatitis, which is marked by severe skin scaling; heat rash; scleroderma, which causes hard, tight skin; and ichthyosis — extremely dry, scaly skin.
• Genetic abnormalities. Mutations in certain genes can lead to disorders that affect the sweat glands.

Prevention of Anhidrosis

Anhidrosis often can’t be prevented, but serious heat-related illnesses can. To stay safe:

• Wear loose, light clothing when it’s warm.
• Stay indoors on hot days.
• Monitor your activity level closely so you don’t overdo.
• Learn the signs of heat-related illness and how to treat them.

If there is a danger of overheating, take the following measures:

• Take a cool shower or sit in a bathtub with cool water
• Drink plenty of fluids
• Stay in a cool environment
• Move slowly
• DO NOT do heavy exercise

Complications of anhidrosis

Heat-related illnesses are the most serious complications of anhidrosis. Children are especially vulnerable because their core temperatures rise faster than adults’, and their bodies release heat less efficiently.

Heat-related problems include:

• Heat cramps. These muscle spasms, which can tighten muscles in your legs, arms, abdomen and back, are generally more painful and prolonged than are typical nighttime leg cramps.
• Heat exhaustion. Signs and symptoms such as weakness, nausea and a rapid heartbeat usually begin after strenuous exercise. Monitor someone with heat exhaustion because symptoms can quickly become worse.
• Heatstroke. This life-threatening condition occurs when your body temperature reaches 104 F (40 C) or higher. If not treated immediately, heatstroke can cause hallucinations, loss of consciousness, coma and even death.

Diagnosis of anhidrosis

Your doctor is likely to suspect anhidrosis based on your signs and symptoms, your medical history, and a physical exam. But you may need certain tests to confirm the diagnosis. These include:

• Sweat test. During this test, known as thermoregulatory sweat test, you’re coated with a powder that changes color when and where you sweat. You then enter a chamber that causes your body temperature to increase to a level that makes most people perspire. Digital photos document the results, and the whole body surface can be tested at once.
• Skin biopsy. In some cases, your doctor might request a biopsy of the area suspected of anhidrosis. For this test, skin cells and sometimes sweat glands are removed for examination under a microscope.

Treatments of Anhidrosis

Anhidrosis that affects a small part of your body usually isn’t a problem and doesn’t need treatment. But large areas of decreased perspiration can be life-threatening. Treatments may depend on the condition that’s causing the anhidrosis.

Treating heat-related problems

Overheating needs prompt treatment to prevent symptoms from becoming worse.

Heat cramps

To relieve cramping:

• Rest and cool down
• Drink cool fruit juice or a sports drink that contains electrolytes
• Get medical care if cramps become worse or don’t go away in about an hour
• Wait at least several hours before returning to strenuous activity

Heat exhaustion

Act quickly when someone develops signs and symptoms of heat exhaustion, such as nausea, dizziness and a rapid heartbeat:

• Move the person into a shady or air-conditioned space, and elevate his or her legs slightly.
• Loosen the person’s clothing, and remove any heavy pieces of clothing.
• Have the person drink a cool beverage that doesn’t have caffeine or alcohol.
• Spray or sponge the person with cool water.
• If symptoms don’t improve quickly, call 911 or emergency medical help.

Heatstroke

Heatstroke requires immediate medical care, so call your local emergency number and get emergency medical help. This condition can be fatal if left untreated.

Until help arrives:

• Move the person into a shady or air-conditioned space.
• Spray or sponge the person with cool water. Or wrap him or her in wet towels or sheets. Use a fan or newspaper to increase air circulation.
• Have the person drink a cool beverage that doesn’t have caffeine or alcohol if he or she is able.

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