Systemic medications may be used for the treatment of generalized or focal hyperhidrosis. They may be useful for patients with cranio-facial hyperhidrosis, focal hyperhidrosis affectiong large areas such as the back, multifocal hyperhidrosis, hyperhidrosis that is not satifactorily treated with other methods, or temporary, short-term event-specific hyperhidrosis management (ex. for a wedding, speech, or performance).
Many of the drugs reported useful for hyperhidrosis have not been studied in controlled trials, their use being based only on anecdotal evidence. Furthermore, at the doses likely to inhibit hyperhidrosis, side effects can be limiting. In addition many of these drugs are not approved by the US Food and Drug Administration specifically for the treatment of hyperhidrosis.
The most commonly used agents are anticholinergics, which block the sympathetic stimulation of eccrine glands by inhibiting the action of acetylcholine at the synapse. Use of these drugs is limited, however, by the common side effects of the anticholinergic class—dry mouth, urinary retention, constipation, and visual disturbances such as mydriasis and cycloplegia.[9,19] It may be possible to manage such side effects by adjusting the dose. It should be noted that studies (in JAMA Neurology 2016 and JAMA Internal Medicine 2015) have reported a potential link between the development of dementia and/or brain atrophy and long-term, high-level anticholinergic use in patients over the age of 65.
Anticholinergics used for hyperhidrosis include propantheline, glycopyrronium bromide, oxybutynin, and benztropine. Anticholinergic therapy is generally not recommended in patients with glaucoma (especially narrow-angle glaucoma) and those who have impaired gastric emptying or a history or symptoms of urinary retention. Patients should be aware of risks of overheating when using anticholinergics. Athletes, people who work outdoors and anyone who may potentially cause themselves injury by becoming overheated must use extra care when considering these treatments. Patients or parents of children taking the medication must remain aware of temperature, water intake, exertion, and any symptoms of overheating.
Two common anticholinergic medications are available in liquid formulations, which may helpful for children who suffer from hyperhidrosis: a liquid form of glycopyrrolate (Cuvposa) indicated to reduce drooling in pediatric cerebral palsy patients. Oxybutynin is also available in a liquid formulation indicated for pediatric patients with certain bladder and urinary conditions.
Some physicians have had success treating palmar and/or plantar hyperhidrosis by adding a crushed anticholinergic to iontophoresis water.
When stressful situations are a trigger for hyperhidrosis, use of an anticholinergic agent or a benzodiazepine prior to an event likely to provoke anxiety may be helpful. Long-term use of benzodiazepines such as diazepam is limited by development of dependency, and many patients cannot tolerate the sedative effects of these drugs. Some patients are able to take diazepam 5 mg at bedtime for several weeks to get used to its sedating effect and then use it as needed for anxiety-provoking events.