We know why we sweat. It's in response to an increase in body temperature. The brain tells the sympathetic nervous system the body needs to cool down, the nerves tell the sweat glands to secrete fluid, and the sweat glands do their thing.
What we don't know is exactly why some people sweat so much more than they need to. The sweat glands are secreting too much, yes; but precisely why the sweat glands are doing this is not entirely clear. The problem could originate in the brain, specifically in the anterior cingulated cortex, according to the Mayo Clinic. The New Zealand Dermatologic Society reports that it may, alternately, be a malfunction in the sympathetic nerves that trigger the sweat glands.
In the case of primary, focal hyperhidrosis, there is evidence the condition is genetic, and it typically shows up by the end of adolescence. It's unclear exactly what triggers episodes of focal hyperhidrosis: Some believe it can be caused by stimuli similar to those that trigger normal sweating, such as heat, anxiety, exercise or spicy food; others propose it results mostly from emotional triggers like nervousness and anxiety.
Secondary, generalized hyperhidrosis, on the other hand, most often happens during sleep, when most people don't sweat much at all. It's triggered by a medical condition or a medication, not only prescription but also over-the-counter.
Because hyperhidrosis could indicate a bigger, underlying problem, it's especially important to seek medical advice if you think you sweat excessively. Some conditions that can cause overactive sweat glands include:
- Heart disease
- Parkinson's disease
A few of the possible trigger medications for secondary hyperhidrosis include:
- Desipramine (Norpramin)
- Esomeprazole (Nexium)
- Fluoxetine (Prozac; Sarafem)
- Nortriptyline (Pamelor)
- Pilocarpine (Isopto Carpine; Pilopine HS; Salagen)
- Protriptyline (Vivactil)
- Zinc supplements
For extensive lists, see IHHS: Diseases and Conditions and Drugs/Medications.
Regardless of the exact cause, hyperhidrosis does have a fairly broad range of treatment options. Which treatment is appropriate depends on the severity of the sweating.