Sweating, or perspiration, is a normal physiological function of the body to control the body temperature. As the water in the sweat evaporates, it absorbs heat and cools the skin and body. Sweating especially at the underarm is expected after a vigorous exercise or on a hot day. However, when a person experiences excessive sweating at certain parts of the body, it is called focal hyperhidrosis. As excessive underarm sweating is very distressing, many patients seek treatments to stop underarm sweating permanently.
A person is diagnosed with primary focal hyperhidrosis when there is visible excessive sweating at limited areas for at least 6 months with no apparent cause. Typically, the symptom is at both left and right sides, occurs at least once a week, stops during sleep, and appears before 25 years old. It is usually limited to the axillae (underarms), palms and soles due to the normally large amounts of sweat glands in those areas. Besides, patients with underarm hyperhidrosis often complain of skin macerations, clothes staining and an increased tendency to get other skin disorders. Apart from the physical nuisance, patients also face psychological stress as excessive sweating impairs daily activities and often results in social problems on both personal and professional levels.
It is important to know that permanent solutions do not exist in medicine. Effective treatments, however, are able to control the symptoms and achieve satisfactory results. First-line therapies recommended for excessive underarm sweating are antiperspirants and topical glycopyrronium.
Antiperspirants are the most preferred choice as they are easily available, inexpensive and well-tolerated. These non-prescription antiperspirants containing low doses of aluminium work by obstructing the sweat glands and reducing sweating. This is helpful for those with very mild hyperhidrosis. Deodorant, on the other hand, only kills the odour but does not limit sweating. For patients that fail to respond to non-prescription antiperspirants, stronger acting antiperspirants such as 20% aluminium chloride hexahydrate may be prescribed. Apply antiperspirants every night when sweating is at a minimum and wash it off in the morning. Only apply it on dry clean skin, best after bathing, to allow medications to take its full effect. Once improvement is noted, the application can be spaced to once a week for a longer-lasting effect. Occasionally, skin irritation may occur with strong antiperspirants. Use 2.5% hydrocortisone cream to alleviate the skin irritation.
An alternative to antiperspirant is topical glycopyrronium, which is an anticholinergic drug that stops sweating by inhibiting the action of acetylcholine on sweat glands. Using a pre-moist cloth, apply topical glycopyrronium 2.4% once daily to the underarms. Side effects of this medication include skin irritation, dry mouth and dilated pupils that can cause blurry vision.
Second-line therapies are offered to patients who have more severe primary focal hyperhidrosis that do not respond well to antiperspirants or topical glycopyrronium. Examples are botulinum toxin and microwave thermolysis.
Botulinum toxin, commonly known as botox, can be injected into the skin at underarms to treat hyperhidrosis. It is a safe and effective method but treatment can be painful and expensive. Botulinum toxin works by blocking the release of acetylcholine from the presynaptic junctions of both neuromuscular and cholinergic autonomic neurons. By blocking acetylcholine, it can temporarily reduce the production of sweat. Presently, the FDA-approved formula of botulinum toxin as an underarm hyperhidrosis treatment is onabotulinumtoxinA (BTX-A). Patients should feel improvement in 2 to 4 days of injection and the effect typically lasts for the next 3 to 9 months. Subsequent injections may be needed to lengthen the effect. To reduce the pain during injections, a topical anaesthetic can be applied.
Lastly, microwave thermolysis uses wave energy to destroy sweat glands in order to reduce sweating in the underarms. Although this technique has been approved by the FDA, it is expensive and is only available in a few facilities. A study showed a reduction of up to 75% of sweat production in the underarms after 6 months of treatment. The recommended program consists of 2 30-minute sessions over 3 months. Common side effects include changes in skin sensation and discomfort.
