What to do about excessive sweating?
Sweating that exceeds the needs of the body—medically termed
hyperhidrosis—is fairly common, affecting 1%–3% of the
population. Hyperhidrosis may be generalized but most often it involves
the palms, underarms, feet, and groin; it can take a social toll, making
handshaking unpleasant and some handwork impossible.
We need sweating to control body temperature; water evaporating from
the skin cools the body. Sweating is under the control of the sympathetic
nervous system, which orchestrates the body’s reaction to stressful
situations and emergencies. The sympathetic nervous system activates
the sweat glands through the chemical messenger acetylcholine. People
with hyperhidrosis produce several times more sweat than normal because
they are particularly sensitive to this signal. Hyperhidrosis seems to
run in families, but we don’t know much more about what causes
Generalized sweating could be a sign of a hormonal condition, infection,
cancer, or anxiety disorder that requires treatment. To be sure, you
should see your clinician. Most of the time, though, excessive sweating
is not dangerous but simply embarrassing and inconvenient.
Hyperhidrosis can be treated in several ways. Topical antiperspirants
are the first-line treatment for underarm sweating and are also effective
on hands and feet. The best choice is a preparation containing aluminum
salts, such as aluminum chloride. The aluminum salt irritates the sweat
gland and causes it to swell, preventing the sweat from leaving. People
who sweat excessively generally need antiperspirants with 10%–15%
aluminum salts. These are applied at night once or twice a week and may
require sleeping with the armpits wrapped in plastic wrap, or plastic
wrap and gloves or socks on the hands or feet. The main side effect is
A procedure called iontophoresis has been used for more than 50 years
to treat excessive sweating on the hands or feet, and more recently,
in the underarm. Your hands or feet are submerged in lukewarm tap water
for 10–20 minutes while a mild electric current is passed through
the water. Apparently this temporarily blocks the sweat gland, although
experts don’t know exactly how it works. Sweating symptoms usually
improve after 5–10 sessions at the rate of three or four sessions
per week. Most people need one or two sessions per week thereafter to
maintain sweat relief. The main side effect is dry or irritated skin.
You should avoid iontophoresis if you are pregnant or have a cardiac
pacemaker or a metal orthopedic implant.
Botulinum toxin (Botox) injections are FDA-approved for treating underarm
hyperhidrosis. They have also been found effective for hands and feet
and are the treatment of choice for marked hyperhidrosis. Multiple injections
are required; a typical underarm treatment involves 12–14 injections
per armpit. Botox appears to work by temporarily paralyzing the nerves
that release acetylcholine. Patients notice complete relief within a
day or two, and the effects last 6–10 months. Injections into the
palms and soles can be painful; those in the armpits, less so. Risks
include bleeding at the injection site and muscle weakness in the hands.
Some doctors prescribe oral anticholinergic medications (drugs that
reduce the activity of acetylcholine) to curb the sweat glands, but this
approach is not approved by the FDA. Anticholinergic medications can
cause some undesirable side effects, such as dry mouth, constipation,
impaired taste, blurred vision, and heart palpitations.
In severe cases, surgery can be performed to cut the sympathetic nerves
to the sweat glands (sympathectomy). Sympathectomy works best for sweaty
To learn more
You can read more about hyperhidrosis at www.sweathelp.com,
the Web site for the International Hyperhidrosis Society.
October 2005 Update
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