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Botox is most well known for reducing facial expression activity and the wrinkles that they cause. Less known, but no less appreciated, is its use for excessive sweating or hyperhidrosis. This is another FDA-approved indication for Botox use. For those afflicted with excessive armpit or axillary hyperhidrosis, the relief from the constant wetting and staining of shorts and the embarrassment that it can cause is significant. For reasons not completely understood, the duration of action of Botox for hyperhidrosis is considerably longer than its effect on diminishing facial muscle movement.

Any type of excessive sweating not even as well recognized as axillary hyperhidrosis is what is known as craniofacial or scalp and forehead hyperhidrosis. This is excessive sweating of the scalp and forehead mainly. Patients report symptoms such as sweat pouring from their forehead while just sitting or beads of sweat that form and run down with nonstrenuous activities. From a diagnosis standpoint, it can be difficult to differentiate between heavy sweating from heat or exercise and true hyperhidrosis of the face or scalp. But if the sweating, regardless of the reason, is bothersome then treatment options should be considered.While the traditional  approach to any type of hyperhidrosis are topical solutions, these are problematic above the neck. Strong antiperspirant products can be irritating to the skin of the face, head, or scalp (can be impossible to apply due to hair) and are usually not  a good solution. Prescription medications, such as anticholinergics, can also be used but they have definite side effects including dry mouth, blurry vision, and constipation.

Like its use in the axilla, Botox can be very effective for excessive scalp and forehead sweating. Injection technique is critical and should not be confused with how it is placed for forehead and glabellar wrinkles. The injection should be placed just under the skin and not deeper into the muscle or galea. If Botox is injected deeper in the muscle or too close to it, diffusion may occur causing some forehead asymmetry. This is a very minor problem and can easily be balanced out with additional Botox injections. If the injections are well placed and symmetric, however, any effect on the frontalis muscle will be balanced and not problematic.

Given the limited zone of diffusion for Botox (1 cm. or less), the location of the injections is critical. I have found that the best location is along the hairline from one temporal area to the other. Since most excessive scalp and forehead sweating is in men, one should use the original hairline whether hair still exists there or not. There is always a pretty clear demarcation between the original scalp and the non-hair bearing forehead. Spacing 4 unit injections about 2.5 cms apart, the usual starting dose is 32 units. That can be adjusted to higher dosing dependent on the degree of response or residual sweating zones. 
For those bothered by excessive and embarrassing forehead and scalp sweating, Botox injections can offer a significant and sustained improvements. Reduction or elimination of the sweating lasts for at least six months or longer. The newer Dysport botulinum injection should be presumed to have similar success.

Dr. Barry Eppley

Indianapolis, Indiana

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