As your built-in cooling system, sweating is necessary. But excessive perspiration isn't, even in the summer. While there's no official definition of excess, here's a good gauge: If you need a wardrobe change after doing nothing more strenuous than grabbing lunch around the corner, you may want to rethink your stay-dry strategies. For advice, we turned to New York City dermatologist Francesca J. Fusco, M.D.

The basic facts
Most of your body's 2 million to 4 million sweat glands are found on your soles and palms and in your armpits. Fluctuations in temperature, hormones, and mood cause nerve endings in the skin to activate these glands, and perspiration (the process that regulates heat exchange) follows. You produce sweat, the fluid evaporates, and your skin is cooled.

What to look for
The most common triggers of excessive sweating include:

• A parent who perspired a lot
  Hyperhidrosis (the medical term for chronic, extreme perspiration) may be genetic.



• Anxiety
  Feeling stressed out or tense can activate the nerve endings that make you perspire.



Your period
Elevated levels of female hormones may cause your sweat glands to become primed to pump.


• Spicy foods
  Chili peppers and hot spices release histamines, chemicals that increase blood flow and make your body heat up, which brings on noticeable sweating.