Perspiration Facts

What is sweat?
Sweat is mostly water with small amounts of urea and salts, released by apocrine glands under the skin surface in the armpits and eccrine glands under the skin surface over the face, head, hands and feet.  Sweat’s purpose is to flow over the skin and evaporate, leading to cooling of the skin surface.

What is excessive sweating?
The average individual sweats about 1 liter (1 quart) of fluid/day, most of which goes unnoticed.  The sweating that concerns most people is armpit sweating, which accounts for only ~1% of our body’s daily sweat production.  Only ~1% of people have excessive sweating, known as hyperhidrosis.  Humans can sweat up to 10 liters per day if really hot or working hard.

How does a deodorant work?
Deodorants work by inhibiting or killing bacteria that accumulate on the skin and metabolize sweat into smelly compounds such as trans-3-methyl-2-hexenoic acid and 3-hydroxy-3-methyl-hexanoic acid.  Some deodorants also contain perfumes to mask sweat odors.

How does an antiperspirant work?
Antiperspirants work by reducing the amount of sweat released to the skin surface.  Aluminum salts in antiperspirants combine with the water and salts in sweat to form gel plugs that clog sweat ducts and reduce perspiration.

Does sweat smell?
Sweat has no smell.  It is mostly water, salt, small amounts of urea, proteins and oils.  Its only after bacteria accumulate and metabolize these proteins and oils that an odor develops. 
The primary compound excreted by bacteria causing sweat odor is trans-3-methyl-2-hexenoic acid.

How to reduce sweating and its effects.
Use an effective antiperspirant.
“Clinical strength” antiperspirants have ~3 times the amount of normal antiperspirants and can help to further reduce sweating.
Wear cotton clothing that quickly wicks away moisture from the skin.
Wear loose fitting clothing.
Wear shoes and socks made out of natural materials that draw away excess moisture from the feet.
Avoid spicy foods, alcohol, caffeine and nicotine.
Help sweaty feet by wearing sandals or flip-flops during the summer.

Does sweat stain fabric?
Sweat is colorless and odorless when it leaves the body and does not stain fabric by itself in most individuals.  Bacteria that metabolize sweat can excrete compounds that might stain fabric.    But the primary cause of yellow fabric stains in the armpits is the aluminum salts present in antiperspirants.  These stains can be removed by mixing 1 scoop of OxiClean in a sink full of warm water and let soak overnight.  Rinse and launder.  White sweat stains come from other ingredients in certain antiperspirants and deodorants.  Use a biological detergent to remove these stains.  Ironing fabric with sweat stains may set those stains permanently.

What are night sweats?
MOST night sweats are caused by getting too warm while sleeping.  Sleep with less clothing, or use fewer blankets, or a lighter comforter.  Night sweats can also occur because of illness, fever, infections, hypoglycemia, drug use, narcotic use, and sleep apnea.

What causes menopause sweats?

About 70% of women develop menopausal symptoms at the time menstrual periods cease in the 40s and 50s.  These symptoms include “hot flashes” and cold sweats or night sweats.  The flushes last 30 seconds to 30 minutes and result from diminishing estrogen levels.  Effective ways to combat excessive sweating with hot flushes include showering regularly, using an antiperspirant, wear loose-fitting clothing made of natural fibers, avoid alcohol, caffeine, spicy foods and smoking, keep well-hydrated, exercise regularly, and keep the bedroom cool at night.

What causes stress sweats?
Nervous sweating is a physical reaction to strong emotions like stress or anxiety.  Stress causes the heart rate to increase and can release adrenalin which will augment sweating.  Dehydration (not drinking enough fluids) can cause excessive sweating to help cool the body down.

Why do certain foods cause sweating?
Spicy foods and hot drinks can cause increased sweating.  This is known as gustatory sweating.  They do this by raising the internal body temperature which activates the body’s cooling system (sweating).  Caffeine stimulates sweat glands and alcohol increases blood flow to the skin which can make you sweat more.