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Wednesday, August 13, 2025

Excessive sweating (hyperhidrosis)


Introduction

Hyperhidrosis is a chronic condition characterized by excessive sweating beyond what is necessary for normal thermoregulation. It can affect specific localized areas (primary focal hyperhidrosis) or occur as a generalized phenomenon (secondary generalized hyperhidrosis). The condition can significantly impair quality of life, causing physical discomfort, social embarrassment, and occupational limitations.

Hyperhidrosis occurs due to overactivity of the sympathetic cholinergic fibers that innervate eccrine sweat glands. While sweating is a normal physiological response to temperature regulation and emotional stimuli, in hyperhidrosis, the sweating response is excessive and disproportionate to environmental or physiological needs.

Epidemiology

  • Prevalence: Approximately 2–3% of the population.

  • Age of onset:

    • Primary focal hyperhidrosis: often begins in childhood or adolescence.

    • Secondary hyperhidrosis: onset can occur at any age depending on underlying cause.

  • Gender: Affects both sexes, with some studies suggesting a slightly higher prevalence in women for axillary hyperhidrosis.

  • Family history: Seen in 30–50% of primary hyperhidrosis cases.

Etiology and Classification

1. Primary (Idiopathic) Hyperhidrosis

  • Localized excessive sweating without an underlying medical cause.

  • Thought to result from overstimulation of eccrine sweat glands by the sympathetic nervous system.

  • Common sites:

    • Palms (palmar hyperhidrosis)

    • Soles (plantar hyperhidrosis)

    • Axillae (axillary hyperhidrosis)

    • Face/scalp (craniofacial hyperhidrosis)

  • Typically bilateral and symmetrical.

  • Sweating often worsens with emotional stress but not during sleep.

2. Secondary Hyperhidrosis

  • Caused by an underlying medical condition or medication.

  • Possible causes:

    • Endocrine/metabolic disorders (hyperthyroidism, diabetes mellitus, hypoglycemia, menopause, pheochromocytoma)

    • Neurological disorders (Parkinson’s disease, spinal cord injury, peripheral neuropathies)

    • Infections (tuberculosis, HIV, malaria)

    • Malignancies (lymphoma, leukemia)

    • Cardiovascular disorders (heart failure)

    • Medications (SSRIs, opioids, hypoglycemics, cholinergic agents)

  • Usually generalized and may occur during sleep.

Pathophysiology

Sweating is regulated by the hypothalamic thermoregulatory center, which stimulates sympathetic cholinergic postganglionic fibers to release acetylcholine, activating muscarinic receptors (M3) on eccrine sweat glands.
In primary hyperhidrosis:

  • The number of sweat glands is normal.

  • The sweat output per gland is excessive due to overactive sympathetic stimulation.

Risk Factors

  • Family history of hyperhidrosis

  • Early onset before age 25 (for primary type)

  • Triggers: heat, humidity, stress, spicy foods, alcohol, caffeine

Clinical Features

Primary Hyperhidrosis

  • Symmetric excessive sweating localized to palms, soles, axillae, or face.

  • Episodes occur at least once per week during waking hours.

  • Sweating absent during sleep.

  • Significant impact on daily activities.

Secondary Hyperhidrosis

  • Generalized sweating affecting the entire body.

  • May occur during sleep.

  • Associated symptoms from underlying cause (e.g., weight loss, tachycardia, tremor).

Diagnosis

History

  • Onset, duration, pattern (localized vs. generalized), triggers, impact on quality of life.

  • Family history.

  • Review of medications.

  • Symptoms suggesting secondary causes.

Physical Examination

  • Distribution and symmetry of sweating.

  • Skin changes (maceration, erythema, secondary infections).

  • Signs of systemic disease.

Investigations

  • Primary hyperhidrosis is diagnosed clinically.

  • For suspected secondary causes:

    • Thyroid function tests (hyperthyroidism)

    • Blood glucose (diabetes, hypoglycemia)

    • CBC, ESR, CRP (infection, inflammation, malignancy)

    • Hormonal tests (cortisol, catecholamines if pheochromocytoma suspected)

  • Starch–iodine test (Minor’s test) – to map areas of excessive sweating.

  • Gravimetric measurement – quantifies sweat production.

Management

Management depends on whether hyperhidrosis is primary or secondary.

1. Treat Underlying Cause (Secondary Hyperhidrosis)

  • Endocrine disorders: Antithyroid drugs for hyperthyroidism (e.g., methimazole), hormone therapy for menopause.

  • Infection: Appropriate antimicrobial therapy.

  • Drug-induced: Dose adjustment or switching medications.

2. Symptomatic Management for Primary Hyperhidrosis

Topical Therapy

  • Aluminum chloride hexahydrate 20% (first-line for axillary, palmar, plantar hyperhidrosis)

    • Applied nightly to dry skin for 1–2 weeks, then 1–2 times weekly.

    • Blocks sweat gland ducts by precipitating proteins.

  • Side effects: Skin irritation, contact dermatitis.

Topical Anticholinergics

  • Glycopyrronium bromide 2.4% cloths – approved for axillary hyperhidrosis.

  • Oxybutynin gel – off-label for localized sweating.

Oral Medications

Used when topical measures fail or in generalized hyperhidrosis.

  • Anticholinergics:

    • Oxybutynin: Start 2.5–5 mg once or twice daily, titrate to effect.

    • Glycopyrrolate: 1–2 mg once or twice daily.

  • Side effects: Dry mouth, blurred vision, constipation, urinary retention.

  • Beta-blockers (e.g., propranolol) or benzodiazepines (e.g., clonazepam) may help if symptoms are anxiety-related.

Botulinum Toxin Injections

  • OnabotulinumtoxinA:

    • Injected intradermally into affected area.

    • Blocks acetylcholine release at neuromuscular junction of sweat glands.

    • Duration: 4–9 months of relief.

  • Used for axillary, palmar, plantar, and craniofacial hyperhidrosis.

  • Side effects: Injection site pain, transient muscle weakness (palms).

Iontophoresis

  • Electrical current passes through water to block sweat gland function.

  • Used for palms and soles.

  • Sessions: 3–4 times per week initially, then maintenance weekly.

  • May combine with anticholinergic agents in water for enhanced effect.

Microwave Thermolysis

  • Microwave energy (e.g., miraDry®) destroys sweat glands in the axillae.

  • Permanent reduction of sweating in treated area.

Surgical Intervention

Reserved for severe refractory cases.

  • Endoscopic Thoracic Sympathectomy (ETS):

    • Disruption of sympathetic chain at T2–T4 levels.

    • Indicated for severe palmar hyperhidrosis.

    • Risks: Compensatory sweating, Horner’s syndrome, pneumothorax.

  • Axillary sweat gland excision/curettage/liposuction for axillary hyperhidrosis.

Lifestyle and Self-Care

  • Wear breathable clothing, moisture-wicking fabrics.

  • Use absorbent pads in clothing for axillae.

  • Avoid known triggers (spicy foods, caffeine, alcohol).

  • Maintain healthy weight.

Prognosis

  • Primary hyperhidrosis often persists for years, but may improve with age.

  • Secondary hyperhidrosis resolves if the underlying cause is treated.

  • Quality-of-life impact can be significant, but multiple effective treatments exist.




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