Hyperhidrosis · What Is It, Causes, Treatment, and More

Hyperhidrosis is a medical condition that causes a person to sweat much more than is physically necessary in one or more parts of the body. 

Sweating is an essential bodily function that helps to regulate body temperature and prevent the body from overheating. People with hyperhidrosis have overactive sweat glands that produce more sweat than required to cool the body. Although hyperhidrosis is not a dangerous condition, it can be a source of significant stress and social embarrassment for some individuals, as it can interfere with their everyday activities and personal relationships.   

Sweat comes from two types of sweat glands, the eccrine and apocrine glands, both of which are under the control of the sympathetic nervous system. The sympathetic nervous system is activated in response to stressful or frightening situations; it triggers the “fight or flight” response. Eccrine sweat glands are widely distributed throughout the body and produce an odorless, clear sweat. When there is a rise in body temperature, the sympathetic nervous system activates eccrine sweat glands to release sweat in order to cool the body down. Conversely, apocrine sweat glands are mainly located on the underarms and groin area. The apocrine glands typically produce a fatty sweat that gives those areas their characteristic body odor scent. Rather than responding to body temperature, apocrine glands release sweat in response to emotional stress or anxiety. 

Hyperhidrosis can be classified as primary or secondary, depending on the underlying cause.

Primary hyperhidrosis, also known as primary focal hyperhidrosis, is the type of hyperhidrosis that is not a symptom of an underlying medical condition or the side effect of medication. Primary hyperhidrosis often begins in childhood or adolescence, and it is thought to occur due to an overstimulation of the sympathetic nerve fibers that control sweating. Primary hyperhidrosis typically causes sweat in focal, or specific, areas of the body, such as the underarms, head, hands, or feet. Moreover, it tends to affect both sides of the body. Depending on the area affected, primary hyperhidrosis can be further classified into axillary hyperhidrosis (i.e., sweaty underarms), palmar hyperhidrosis (i.e., sweaty hands), plantar hyperhidrosis (i.e., sweaty feet), and craniofacial hyperhidrosis (i.e., sweaty face or head).  

Secondary hyperhidrosis occurs as a result of an underlying cause. Unlike primary hyperhidrosis, secondary hyperhidrosis affects the entire body and commonly presents later in life. There are a variety of conditions that can lead to secondary hyperhidrosis, including endocrine disorders (e.g., increased thyroid function), diabetes mellitus, infections (e.g., tuberculosis, malaria, HIV infection), neurological conditions (e.g., stroke or Parkinson disease), and certain types of cancer, (e.g., Hodgkin lymphoma). Finally, secondary hyperhidrosis can be a side effect of some medications, such as antidepressants (e.g., selective serotonin reuptake inhibitors), or substance use, including heavy alcohol consumption or withdrawal.

Primary hyperhidrosis appears to have a genetic component, as the condition can sometimes run in families. Regarding secondary hyperhidrosis, some individuals may be genetically predisposed to conditions that can cause secondary hyperhidrosis (e.g., diabetes, Parkinson disease), while others may develop secondary hyperhidrosis with no associated genetic factors.

Hyperhidrosis can be diagnosed clinically based on a careful medical history and physical exam. Initial assessment typically focuses on determining the severity and type of hyperhidrosis, as well as identifying any underlying medical conditions. 

In cases of focal hyperhidrosis, a Minor’s iodine-starch test may help assess the degree of excessive sweating and effectiveness of hyperhidrosis treatments. This test is performed by applying an iodine solution to the skin, followed by a thin layer of starch powder. Once sweating begins, the mixture turns dark blue in color, outlining the area affected by hyperhidrosis. 

Treatment of primary focal hyperhidrosis can be challenging and time consuming, as many treatments offer only temporary relief or do not work consistently over time. 

Over-the-counter (OTC) antiperspirants are most commonly applied to manage axillary hyperhidrosis, but they can also be applied to the hands or feet to reduce sweating in those areas. Most antiperspirants contain small amounts of aluminum salts, such as aluminum chloride, which interact with components of sweat and form a plug that temporarily blocks sweat release. Although antiperspirants can reduce visible sweating for a few hours, they may irritate the skin, possibly causing a burning or tingling sensation. Unlike antiperspirants, conventional deodorants do not reduce sweating; they only prevent growth of the bacteria responsible for body odor or mask the odor with fragrance. 

Surgery is another treatment option for primary focal hyperhidrosis. Surgeons can remove small areas of sweat glands from areas that produce excessive sweat, or, through a more invasive procedure called endoscopic thoracic sympathectomy (ETS), surgeons can cut off the sympathetic nervous supply to sweat glands. Because surgery is permanent and carries significant risks, it is usually considered only when excessive sweating persists despite more conservative measures. 

Finally, individuals with generalized hyperhidrosis may benefit from oral treatment with anticholinergic medications, like oxybutynin or glycopyrronium. These medications work by blocking the activity of the  sympathetic nervous system, thereby reducing sweating. Although anticholinergics can be effective for some individuals with hyperhidrosis, they may produce a variety of side effects, including blurry vision, dry mouth, palpitations (i.e., the sensation of the heart pounding inside the chest), and trouble urinating. In order to avoid the side effects of oral medications, pre-moistened cloths containing glycopyrronium, one of these medications, have been recently approved to treat excessive underarm sweat.

In cases of secondary hyperhidrosis, treatment often involves addressing the underlying medical condition or discontinuing any medications that may be causing the sweating as a side effect.