<Things you should know> The correct knowledge about "odor": Causes, prevention, and treatment of "hyperhidrosis" About hyperhidrosis Main causes of hyperhidrosis Is this hyperhidrosis? A self-check method you can do right now Methods to prevent hyperhidrosis Treatments for hyperhidrosis Our bodies sweat when we exercise, eat spicy food, or feel nervous. However, some people may be troubled by sweating even when it's not hot, or by sweating more than others. This time, we will introduce hyperhidrosis, a condition where you sweat more than necessary, under the supervision of a dermatologist. About hyperhidrosis Even though we refer to it simply as hyperhidrosis, the areas where sweating occurs and the causes of excessive sweating vary from person to person. In other words, even if you receive the same diagnosis of hyperhidrosis, the symptoms and treatment methods will differ from person to person. Here, let's first cover the basic knowledge, such as the definition and types of hyperhidrosis. What is hyperhidrosis? We humans are "warm-blooded animals" that must maintain a constant body temperature regardless of the surrounding environment or our physical condition to survive. However, our body temperature rises on hot days, when we exercise, or when we eat and convert food into energy. That's when sweat comes in. Eccrine sweat glands on the surface of our skin secrete sweat, and as it evaporates, it absorbs heat through evaporation, thus lowering our body temperature.However, some people sweat more than is necessary for regulating their body temperature, which can interfere with their daily lives. This is called hyperhidrosis. For various reasons (more details below), the function of the eccrine sweat glands becomes abnormally high. Types of hyperhidrosis Hyperhidrosis can be classified into two types: "generalized hyperhidrosis," where excessive sweating occurs throughout the entire body, and "localized hyperhidrosis," where excessive sweating occurs locally, such as on the palms of the hands or soles of the feet. The causes differ for each type; for example, generalized hyperhidrosis can be caused by conditions such as hyperthyroidism or diabetes, while localized hyperhidrosis can be caused by mental stress or damage to peripheral nerves.Excessive sweating caused by some kind of disease is called "secondary hyperhidrosis." On the other hand, in some cases, the cause of both generalized and localized hyperhidrosis is unknown. This is called "primary hyperhidrosis," and it is said to be more common in younger generations.Key characteristics include similar symptoms in family members and the absence of excessive sweating during sleep. Areas where hyperhidrosis occurs In cases of generalized hyperhidrosis, the entire body sweats profusely. In cases of localized hyperhidrosis, sweating occurs in specific areas such as the palms of the hands, soles of the feet, head, face, and armpits.If excessive sweating is observed in the palms of the hands and soles of the feet, it is called "palmoplantar hyperhidrosis"; if it is only in the palms, it is called "manual hyperhidrosis"; if it is in the soles of the feet, it is called "plantar hyperhidrosis"; and if it is in the armpits, it is called "axillary hyperhidrosis." Main causes of hyperhidrosis As briefly mentioned earlier, there are various causes of hyperhidrosis. From here, let's look at the main causes, divided into generalized hyperhidrosis and localized hyperhidrosis. Causes of generalized hyperhidrosis ■ Thermoregulatory sweating: Exercise, high temperature environment, fever, etc. ■ Endocrine and metabolic sweating: Menopausal disorders, hyperthyroidism, diabetes, obesity, etc. ■ Sweating due to nerve disorders: Parkinson's disease, etc. ■ Sweating due to drug side effects: Taking psychotropic drugs, hypnotics, nonsteroidal anti-inflammatory drugs, steroids, etc. ■ Sweating due to infectious diseases: Tuberculosis, sepsis, etc. ■ Idiopathic sweating: Cause unknown Causes of localized hyperhidrosis ■ Psychogenic sweating: Caused by mental tension (palms, soles of feet, armpits, etc.) ■ Gustatory sweating: When eating spicy food (on the face) ■ Sweating due to nerve damage: such as after thoracic sympathectomy (trunk) ■ Other: Localized hyperhidrosis due to skin disease, etc. The most common cause of localized hyperhidrosis is said to be mental stress. Furthermore, localized hyperhidrosis other than in the palms and soles of the feet is often caused by neurological disorders. This possibility is even stronger if the areas of excessive sweating are asymmetrical.In addition, excessive sweating can also be caused by medication side effects. If you are prescribed antidepressants, anti-anxiety medications, oral nonsteroidal anti-inflammatory drugs, or steroids, the possibility of excessive sweating due to the medication is high, so it would be a good idea to check with your doctor. Is this hyperhidrosis?Self-check methods you can do right now If any of the following apply to you, you may have hyperhidrosis (excessive sweating). Sometimes I sweat even when it's not hot or I haven't exercised. I'm worried about foot odor. Yellowish sweat stains appear under the armpits of clothing. When I get nervous, my palms and armpits start to sweat. My palms are often sweaty. When you read a book or take notes, the paper gets wet. Have you ever had someone point out that you have body odor or sweat odor? If you experience the above symptoms occasionally or regularly in your daily life, there is a high possibility that you have severe hyperhidrosis.If your hyperhidrosis is secondary to an underlying medical condition, you may need to seek immediate treatment for the disease causing it, so you should go to the hospital as soon as possible.In addition to these factors, irregular lifestyles, unbalanced diets, alcohol consumption, and smoking are also thought to exacerbate hyperhidrosis. Please reflect not only on your symptoms but also on your lifestyle. Methods to prevent hyperhidrosis The following are some methods for preventing hyperhidrosis (excessive sweating). However, these are all methods to prevent sweating caused by sympathetic nervous system dominance due to stress, etc. They do not prevent hyperhidrosis caused by other factors such as nerve damage. Improving your diet Spicy and sour foods stimulate the sympathetic nervous system, making you sweat more easily. If you suffer from hyperhidrosis (excessive sweating), you should avoid excessive consumption of these stimulants. Caffeine also stimulates the sympathetic nervous system, so it's best to avoid coffee and tea as much as possible. And most importantly, try to eat a well-balanced diet. Lifestyle improvements Maintaining moderate alcohol consumption, refraining from smoking, and getting enough sleep at appropriate times are all essential lifestyle improvements to prevent the sympathetic nervous system from becoming dominant, and in other words, to avoid excessive sweating. Create time to relax Creating time to relax your mind and body, and effectively managing stress, is also an effective way to prevent hyperhidrosis. Cherish the time you spend freeing yourself from tension. Treatments for hyperhidrosis There are several types of treatments for hyperhidrosis used in medical institutions, and the appropriate approach varies depending on the cause and severity of the symptoms. Use topical medications Applying aluminum chloride solution to the affected area is an effective method, as it blocks sweat glands and suppresses sweat secretion. For the armpits, simply applying it directly is sufficient, but for the palms of the hands and soles of the feet, applying the solution to the skin and then covering it with a dressing will provide a more effective treatment for hyperhidrosis. Use oral medication Treatment options include oral medications such as propantheline bromide (covered by insurance), oxybutynin (off-label), and solifenacin succinate. However, the effectiveness of these medications can vary, and they may have side effects, so be sure to listen carefully to your doctor's or pharmacist's explanation before making a choice. Take herbal medicine In the treatment of hyperhidrosis, herbal medicines are sometimes used. The prescribed medication varies depending on the type of hyperhidrosis, but for example, Boi-Ogi-to is recognized for its effectiveness in improving hyperhidrosis and is sold as an over-the-counter (OTC) medicine. Other herbal medicines that may be used, depending on the individual's constitution, include Byakko-ka-ninjin-to, Ryutan-shakan-to, and Daijoki-to. Botulinum injection This method involves injecting botulinum toxin into the affected area to suppress sweating. In Europe and the United States, it is commonly used to treat localized hyperhidrosis of the armpits. In Japan, however, this treatment is not covered by insurance for areas other than the armpits, so it is important to carefully consider the cost and effectiveness before choosing this option. Iontophoresis Iontophoresis is a treatment covered by insurance that involves immersing the palms of the hands or soles of the feet, which tend to sweat a lot, in a container of water and applying an electric current of 10-20 mA for about 30 minutes. It is believed that performing this treatment 8 to 12 times can be effective in improving hyperhidrosis. Sympathetic nerve block This treatment aims to suppress excessive sweating caused by the sympathetic nervous system by surgically removing or cauterizing the sympathetic nerves in the chest. While this used to require major surgery, it's now possible to perform the procedure through a small incision of a few millimeters in the armpit, inserting a camera. The procedure usually takes about 10 minutes. Furthermore, if the cause is a disease such as nerve damage or diabetes, it is necessary to not only implement the treatments described above but also to address the underlying cause. Excessive sweating can very well be a distress signal from your body, so if you notice anything unusual, it is recommended that you consult a doctor first. Furthermore, if hyperhidrosis becomes so severe that it interferes with social communication, there is a risk of developing fear and anxiety about sweating, leading to emotional instability. If you are experiencing mental stress due to sweating, it is advisable to consult a doctor and seek medication if necessary. Supervised by: Dr. Hiroyuki Sato, Director of Jimbocho Station Front Dermatology ClinicAfter graduating from the University of Tokyo Faculty of Medicine, he worked at several hospitals, including the university's affiliated hospital, the Cancer Institute Hospital of Japan, and the Japanese Red Cross Medical Center, before opening Jimbocho Ekimae Dermatology Clinic in 2014. He is a certified dermatologist by the Japanese Dermatological Association. 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