Hyperhidrosis: How safe and effective is oxybutynin?

There are numerous treatment options for excessive sweating, but they all have their drawbacks. What about the anticholinergic oxybutynin?

Types of hyperhidrosis

• A distinction is made between a primary and a secondary forms.
• The cause of primary hyperhidrosis is unclear. It shows a genetic predisposition and often manifests itself before the age of 25.
• Secondary hyperhidrosis is caused by other illnesses or medication.
• According to the Hyperhidrosis Disease Severity Scale (HDSS), four degrees of severity are differentiated.

Why do we sweat?

Sweating is an important physiological mechanism for thermoregulation. The sweat glands secrete a watery secretion that cools us down through evaporation. Sweat also keeps the skin supple and ensures a correct pH value. Finally, sweat glands are also used for detoxification by excreting the body's own waste substances.

Sweat glands are particularly numerous on the face, hand palms, and feet soles, as well as in the axillary region. And this is precisely where they cause problems for people with hyperhidrosis. The emotional, social and occupational impairment can be so great that those affected are severely restricted in their everyday lives.

There is a wide range of treatments available, from topicals and oral substances to injections, tap-water iontopheresis, or microwave therapy, through to invasive procedures such as laser or endoscopic thoracic sympathectomy as a last resort. The first choice is topical aluminium chloride hexahydrate, although this is also a potent irritant and can lead to skin irritation.

How does oxybutynin work in hyperhidrosis?

The muscarinic receptor antagonist oxybutynin acts on the cholinergic innervation of the sweat glands. It occupies their receptors so that acetylcholine can no longer bind to them. However, the substance does not act selectively and can therefore lead to typical anticholinergic side effects.

Oxybutynin has so far only been authorised for the treatment of incontinence and overactive bladder - although its effect on hyperhidrosis has been known since the 1980s and has been proven time and again since then. Researchers led by Egyptian scientist Mohamed El-Samahy scrutinised the active ingredient once again. In their meta-analysis, they included 6 studies with a total of 293 patients suffering from primary or secondary hyperhidrosis who received either oxybutynin or placebo. Efficacy, side effects and quality of life were analysed.

The anticholinergic drug proved to be superior to placebo in terms of its effect as measured by HDSS. It also performed better in terms of central nervous system side effects such as headaches, weakness and dizziness. Quality of life was also improved by the treatment. However, there was no significant difference in dry mouth or transepidermal water loss, which measures diffusion through the skin.

Great potential for oxybutynin, but there are limits

Despite some limitations, the study once again shows the potential of oxybutynin in the treatment of hyperhidrosis. However, whether it is suitable for the individual sufferer must be weighed up individually. Long-term treatment in particular is often limited by the systemic anticholinergic side effects.