What causes hyperhidrosis (excessive sweating)?

Causes of Excessive Sweating (Hyperhidrosis)

Excessive sweating (hyperhidrosis) is primarily classified as either primary (focal) or secondary, with secondary hyperhidrosis being caused by underlying medical conditions, medications, or other factors that require specific diagnosis and treatment. 1

Primary Hyperhidrosis

Primary hyperhidrosis is characterized by:

• Bilaterally symmetric, focal excessive sweating
• Typically affects specific areas: axillae, palms, soles, or craniofacial region
• Often has a genetic component
• Usually begins in childhood or adolescence
• Episodes occur at least weekly
• No sweating during sleep
• No underlying medical cause

Secondary Hyperhidrosis Causes

Endocrine Disorders

• Hyperthyroidism: Common cause with accompanying symptoms like tachycardia, tremors, nervousness, heat intolerance 2
• Diabetes mellitus: Particularly diabetic autonomic neuropathy affecting face and upper body 1
• Hyperpituitarism/Growth hormone excess: Can cause excessive sweating, especially in children with abnormal growth patterns 2, 1

Neurological Disorders

• Autonomic dysreflexia: Particularly in spinal cord injuries above T6 level 2
• Autonomic neuropathies: Can cause regional hyperhidrosis 1

Medications

• Antidepressants: Particularly serotonergic types 1
• Stimulants 2
• Opioid withdrawal 1
• Anticholinesterase inhibitors 1
• Antipsychotics 1
• Loop diuretics 1
• ACE inhibitors 1
• Proton pump inhibitors 1

Infectious Causes

• Tuberculosis: Often associated with night sweats
• Malaria
• HIV/AIDS
• Endocarditis

Malignancies

• Lymphoma
• Leukemia
• Carcinoid tumors
• Pheochromocytoma

Other Conditions

• Congestive heart failure 1
• Obesity 1
• Anxiety disorders and stress 1
• Social anxiety disorder: Often presents with hyperhidrosis, particularly in social situations 2
• Menopause: Hot flashes with sweating
• Alcohol or substance abuse
• Pregnancy

Diagnostic Approach

When evaluating excessive sweating, consider:

1. Pattern of sweating:

   • Generalized vs. focal
   • Symmetric vs. asymmetric
   • Areas affected (axillae, palms, soles, face)

2. Timing and triggers:

   • Onset (childhood vs. adult)
   • Occurs during sleep (suggests secondary cause)
   • Relation to stress, heat, or specific activities

3. Associated symptoms:

   • Weight changes
   • Palpitations
   • Tremors
   • Fever
   • Fatigue
   • Anxiety

4. Medication history:

   • Review all current medications
   • Recent changes in medications

5. Family history:

   • Primary hyperhidrosis often has genetic component

Evaluation Tools

• Hyperhidrosis Disease Severity Scale (HDSS): Validated tool to assess severity and impact on quality of life 1, 3
• Minor's starch-iodine test: Can help visualize areas of excessive sweating

Key Considerations

• Excessive sweating that is generalized, asymmetric, or occurs during sleep strongly suggests secondary hyperhidrosis
• New-onset hyperhidrosis in adulthood should raise suspicion for an underlying medical condition
• Focal, symmetric hyperhidrosis beginning in childhood or adolescence is more likely to be primary
• Consider thyroid function tests in all patients with hyperhidrosis to rule out hyperthyroidism, as it's a common and treatable cause 2
• In patients with diabetes, hyperhidrosis may be a sign of autonomic neuropathy and requires careful evaluation 1

Remember that identifying and treating the underlying cause is essential for managing secondary hyperhidrosis, while primary hyperhidrosis typically requires symptomatic treatments such as topical agents, iontophoresis, botulinum toxin, or in severe cases, surgical interventions.