What Is Hypohidrosis and Anhidrosis?
Hypohidrosis is the medical term for a decreased ability to sweat, while anhidrosis refers to the complete absence of sweating. These conditions can affect the entire body or be localized to a specific area. When sweating is impaired across a large portion of the body, it can significantly compromise the body's ability to regulate its temperature, especially during exercise or in hot weather. This can put an individual at a higher risk for serious heat-related illnesses, such as heat exhaustion and heatstroke.
The Critical Role of Sweating
Sweating plays a crucial role in thermoregulation. When your core body temperature rises due to heat or physical activity, your eccrine sweat glands produce moisture. As this moisture evaporates from the skin's surface, it carries heat away, effectively cooling the body. For those with hypohidrosis, this natural cooling system is faulty, making them more vulnerable to overheating.
Causes of Decreased Sweating
The causes of hypohidrosis or anhidrosis are varied and can be categorized based on what part of the sweating process is affected, from nerve signals to the sweat glands themselves. They can be congenital (present from birth) or acquired later in life.
Neurological Causes
Nerve damage is a common culprit and can result from several conditions that disrupt the signals from the brain to the sweat glands.
- Autonomic Neuropathies: Disorders affecting the autonomic nervous system, which controls involuntary bodily functions, can impair sweating. Conditions like diabetes, alcoholism, and Guillain-Barré syndrome are examples.
- Central Nervous System Disorders: Conditions affecting the brain or spinal cord, such as Parkinson's disease, stroke, or multiple system atrophy, can interfere with sweating.
- Ross Syndrome: A rare syndrome characterized by a triad of symptoms, including segmental hypohidrosis.
Skin and Sweat Gland Issues
Problems directly with the skin or sweat glands can also cause decreased sweating.
- Skin Damage: Scarring from burns, trauma, or radiation therapy can destroy sweat glands in the affected area.
- Clogged Pores: Skin diseases that block sweat ducts, such as psoriasis or miliaria (heat rash), can lead to localized hypohidrosis.
- Connective Tissue Diseases: Disorders like systemic sclerosis and Sjögren syndrome can damage sweat glands.
- Genetic Disorders: Some people are born with a genetic condition like hypohidrotic ectodermal dysplasia, which causes underdeveloped or absent sweat glands.
Medication-Induced Hypohidrosis
Many prescription drugs can interfere with sweat gland function as a side effect.
- Anticholinergics
- Tricyclic antidepressants
- Antihistamines
- Bladder antispasmodics
- Antipsychotics
- Opioids
Other Potential Causes
- Dehydration: Excessive dehydration can temporarily cause a decrease in sweating as the body tries to conserve fluid.
- Idiopathic: In some cases, the cause of hypohidrosis cannot be identified.
Recognizing the Signs and Symptoms
Beyond the obvious lack of perspiration, individuals with hypohidrosis may experience other symptoms, especially during heat exposure or physical activity:
- Feeling excessively hot and unable to cool down
- Flushing of the skin
- Dizziness or lightheadedness
- Muscle cramps or weakness
- Nausea
- High fevers, particularly in children
It is also possible to experience compensatory hyperhidrosis (excessive sweating) in unaffected areas of the body, as the body tries to make up for the lack of sweat elsewhere.
Diagnosis and Management
If you suspect you have hypohidrosis, a healthcare provider can perform several tests to confirm the condition and determine its cause.
- Thermoregulatory Sweat Test: The patient is coated with a powder that changes color where they sweat and is then placed in a special chamber to raise their body temperature. This reveals where and how much they are sweating.
- Quantitative Sudomotor Axon Reflex Test (QSART): Electrodes stimulate the sweat glands to assess the function of the nerves that control sweating.
- Skin Biopsy: A small tissue sample may be taken to examine the sweat glands under a microscope.
- MRI: If a neurological cause is suspected, an MRI may be used to examine the brain or spinal cord.
Management focuses on treating the underlying cause, if possible, and preventing heat-related illness. If a medication is the cause, your doctor may suggest an alternative. If no treatable cause is found, a person must take precautions to avoid overheating.
Hypohidrosis vs. Anhidrosis
| Feature | Hypohidrosis | Anhidrosis |
|---|---|---|
| Sweating Level | Decreased, but some sweating still occurs | Complete absence of sweating |
| Effect on Body | Impairs the ability to cool down effectively | Severe impairment or inability to cool down |
| Severity | Can be mild and localized, but may become serious if generalized | Life-threatening if affecting large body areas |
| Symptoms | Heat intolerance, flushing, dizziness | Severe heat intolerance, high risk of heatstroke |
| Management | Depends on the cause, often includes heat avoidance | Critical heat avoidance, emergency cooling in severe cases |
Staying Safe with Decreased Sweating
For those living with this condition, managing symptoms and avoiding complications is key. The following are crucial precautions:
- Stay in air-conditioned environments during hot weather.
- Wear loose-fitting, light-colored clothing made of natural fabrics.
- Drink plenty of fluids, especially water or sports drinks, and avoid alcohol and caffeine.
- Limit strenuous physical activity, especially in the heat.
- Take regular cool showers or baths to help lower your body temperature.
- Use a cool mist humidifier or carry a spray bottle with water to mist your skin.
- Know the signs of heat exhaustion and heatstroke and seek immediate medical attention if they occur.
For more detailed information on living with anhidrosis, see the guide on the Cleveland Clinic's website: Anhidrosis (Lack of Sweat): Symptoms, Causes & Treatment.
Conclusion
Decreased sweating is a real medical condition with various potential causes, from genetics and nerve damage to medication side effects. While mild cases might go unnoticed, widespread hypohidrosis can significantly increase the risk of heat-related illnesses. Recognition of the symptoms and a proper diagnosis are essential for managing the condition and staying safe. By understanding the importance of sweating for thermoregulation, individuals can take proactive steps to avoid overheating and address any underlying health issues with a medical professional.
