Hyperhidrosis

What is Hyperhidrosis?

Hyperhidrosis is a medical condition characterised by sweating that exceeds what is physiologically required for temperature regulation. It is not simply a response to heat, exertion, or emotional stress, but rather a dysregulation of the body's autonomic control of sweat production.

Sweating is an essential thermoregulatory function mediated by eccrine sweat glands. In hyperhidrosis, however, this system becomes overactive, resulting in persistent or excessive sweating even in the absence of appropriate triggers. For affected individuals, the process is continuous or disproportionate, often interfering with daily function and quality of life. At a physiological level, the sweat glands themselves are structurally normal. The dysfunction lies in the signalling pathways that regulate them.

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What are the Types of Hyperhidrosis?

Hyperhidrosis is broadly classified into two distinct forms based on distribution and underlying cause.

1. Primary Focal Hyperhidrosis - This is the most common presentation. It typically begins earlier in life and affects specific anatomical areas, most frequently the palms, soles, axillae, and face. It is characterised by symmetrical sweating and occurs without an identifiable underlying medical condition. Primary hyperhidrosis does not typically occur during sleep, reflecting its basis in daytime autonomic overactivity rather than systemic disease.
2. Secondary Generalised Hyperhidrosis - This form involves more widespread sweating and is usually secondary to an underlying systemic factor. Potential causes include hormonal imbalance (such as hyperthyroidism or menopausal changes), medication-related side effects, and metabolic or neurological conditions. The onset is often later in life, and sweating may occur during sleep. New-onset or nocturnal sweating warrants further medical evaluation to exclude an underlying systemic cause.

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What Causes Hyperhidrosis?

Hyperhidrosis is fundamentally a disorder of neural signalling rather than glandular structure. Sweat production is controlled by the sympathetic nervous system through the release of acetylcholine, a neurotransmitter that activates eccrine glands. In individuals with hyperhidrosis, these signals are exaggerated or inappropriately sustained, resulting in continuous gland stimulation regardless of thermal need. A genetic predisposition is frequently observed, particularly in primary focal hyperhidrosis, suggesting an inherited sensitivity within these neural pathways.

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How is Hyperhidrosis Treated?

Management follows a structured, stepwise approach, guided by severity, distribution, and impact on daily life.

1. Topical Antiperspirants - High-strength formulations containing aluminium salts are typically first-line. These act by forming temporary occlusion within the sweat ducts, reducing surface sweat production. Application technique is critical; products are most effective when applied to completely dry skin, usually at night, when gland activity is reduced.
2. Iontophoresis - This modality is particularly effective for palmar and plantar hyperhidrosis. It involves the use of a low-intensity electrical current delivered through water to disrupt sweat gland activity. Regular sessions are required initially, with maintenance treatments over time to sustain results.
3. Neuromodulator Therapy - Botulinum toxin is an established treatment, particularly for axillary hyperhidrosis. It works by inhibiting acetylcholine release at the neuroglandular junction, thereby reducing sweat production. The effect is temporary but sustained, typically lasting several months.
4. Systemic Therapy - Oral anticholinergic medications may be considered in more extensive or generalised cases. These act centrally to reduce cholinergic stimulation of sweat glands. Their use requires careful clinical supervision due to potential systemic side effects.

Hyperhidrosis is often under-recognised, as individuals may attribute symptoms to lifestyle or environmental factors. However, excessive sweating particularly when persistent, symmetrical, or disproportionate represents a defined medical condition. Distinguishing between primary and secondary forms is essential, as management strategies differ and, in some cases, may require investigation of underlying systemic disease.