Excessive sweating (“hyperhidrosis”) is a chronic condition that can involve many areas of the body and cause significant embarrassment. While there is often no cure, there are multiple treatment options with various pros and cons, including topical medications, pills, and lasers. Injectable neurotoxins are safe and durable treatment alternatives, with specific FDA approval for onabotulinum-A (Botox™) for use on underarms.
Onabatoulinum-A (Botox) is a purified protein that temporarily blocks acetylcholine release. The toxin specifically degrades a protein called SNAP-25, which helps tiny acetylcholine-carrying vesicles to fuse with the nerve surface, and spill their contents outward onto connecting nerves. Without acetylcholine, nerves signals are interrupted until the toxin degrades and SNAP-25 is regenerated.
Botox works on both facial muscular wrinkling and hyperhidrosis because both require acetylcholine: the exact same neurotransmitter molecule that facilitates both (1) muscular contraction and (2) sweat dilution and release from glands. This slight difference in mechanism likely accounts for the longer duration of action on sweat glands when compared to muscles (six months versus 3 months), but the biochemistry is still somewhat unclear.