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.

Simple solutions

Relax
Taking deep, slow breaths when you're anxious can keep the nervous system from triggering sweat production.


• Dust on body powder
  Soak up wetness with a talc-free formula like Origins Organics Refreshing Body Powder ($23; origins.com), which has a light, clean scent.



• Use a maximum-strength antiperspirant
  For best results, apply it at night and then again in the morning. Try one that contains aluminum zirconium trichlorohydrex glycine (which blocks pores and inhibits the release of sweat), like Dove Clinical Protection Anti-Perspirant/Deodorant ($8; at drugstores). Until recently, this ingredient was available only in prescription-strength products.

EXPERT STRATEGY If the soaking won't stop, ask your doctor about Drysol or Xerac AC, prescription antiperspirants with a higher percentage of sweat inhibitors. "Or try Botox," says dermatologist Francesca Fusco, M.D. The injections relax sweat gland—stimulating nerves for up to six months. Go to botoxseveresweating.com for details.

The bottom line You don't have to endure underarm stains just because over-the-counter remedies don't work. Doctor-administered treatments can help.