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Diseases and Conditions
Sweating and body odor
From MayoClinic.com
Special to CNN.com

Introduction

Sitting in the heat of the sun, working out at the gym, giving a presentation at work — all of these activities can make you sweat. It's both natural and healthy to sweat under these conditions. In fact, when you're exposed to heat, exercising strenuously or under extreme emotional stress, you may lose several quarts of fluid in perspiration. A pea-sized bead of sweat can cool nearly 1 liter (about 1 quart) of blood 1 degree Fahrenheit.

Sometimes, however, the complex mechanism of perspiration goes awry, resulting in either excessive perspiration (hyperhidrosis) or little or no perspiration (anhidrosis). Excessive sweating can be embarrassing and may sometimes signal a more serious health problem. Anhidrosis is potentially life-threatening.

Yet for most people, sweating is simply a minor nuisance. The odor that sometimes occurs when you sweat is probably more upsetting. Although perspiration is basically odorless, it can take on an unpleasant smell when it comes into contact with bacteria on your skin. If you find this offensive, you're not alone — Americans spend hundreds of millions of dollars a year on antiperspirants and deodorants.

Signs and symptoms

Healthy people sweat. But when, where and how much varies widely. Factors that cause most people to sweat include:

  • Exercise, especially strenuous exercise
  • Hot weather
  • Nervousness, anxiety or stress

Perspiration that's triggered by emotion is most likely to occur on your face, your underarms, your palms and the soles of your feet. But how much you sweat and even the way your sweat smells can be influenced by your mood, certain foods and beverages, some drugs and medical conditions, and even by your hormone levels. What's more — unfair as it seems — some people inherit a tendency to sweat heavily, especially on their soles and palms.

Because it's almost impossible to define normal sweating, try to learn what's normal for you. That will help you pinpoint any unusual changes.

Causes

Your skin has two types of sweat glands: eccrine glands and apocrine glands. Eccrine glands occur over most of your body and open directly onto the surface of your skin. Apocrine glands develop in areas abundant in hair follicles, such as your scalp, underarms and genitals.

You have between 2 million and 5 million eccrine sweat glands. When your body temperature rises, your autonomic nervous system stimulates these glands to secrete fluid onto the surface of your skin, where it cools your body as it evaporates. This fluid (perspiration) is composed mainly of water and salt (sodium chloride) and contains trace amounts of other electrolytes — substances that help regulate the balance of fluids in your body.

Apocrine glands, on the other hand, secrete a fatty sweat directly into the tubule of the gland. When you're under emotional stress, the wall of the tubule contracts and the sweat is pushed to the surface of your skin where bacteria begin breaking it down. Most often, it's the bacterial breakdown of apocrine sweat that causes a strong odor.

A number of factors can affect how much you sweat and even the way your sweat smells. Certain foods, drugs or medical conditions can cause excessive sweating, whereas drugs or conditions may interfere with your ability to perspire normally.

Excessive sweating (hyperhidrosis)
Some people sweat more than others for no apparent reason. But some factors may make you sweat heavily. These include:

  • Heredity. Some people inherit a tendency to sweat excessively, especially on their palms and the soles of their feet.
  • Certain foods and beverages. Drinking hot beverages and those that contain caffeine or alcohol can make you sweat. Eating spicy foods can do the same thing.
  • Certain drugs. Drugs that can cause excessive sweating include some antipsychotic medications used to treat mental disorders, morphine and excess doses of the thyroid hormone thyroxine. Overdoses of analgesics such as aspirin and acetaminophen (Tylenol, others) also can cause intense sweating.
  • Menopause. Women going through menopause may experience hot flashes — a rise in temperature accompanied by sweating and a feeling of intense heat — due to a drop in estrogen levels. Some menopausal women may also be awakened at night by soaking sweats followed by chills.

  • Low levels of male hormones. Men with low levels of the male hormone testosterone or a condition known as hypogonadism — which causes reduced functioning of the testicles — also can have hot flashes.

  • Low blood sugar (hypoglycemia). This occurs when the level of sugar in your blood drops below a certain level. It's most common in people with diabetes who take insulin or oral medications that enhance the action of insulin. Early signs and symptoms include sweating, shakiness, weakness, hunger, dizziness and nausea. Some people may develop low blood sugar after eating, especially if they've had stomach or intestinal surgery. In rare cases your body may produce too much of the pancreatic hormone insulin, leading to low blood sugar.

  • Fevers. A fever occurs when your temperature rises above its normal range. You may have a fever with many types of bacterial and viral infections. When your body temperature finally begins to return to normal, known as "breaking of the fever," you may sweat profusely, which is your body's way of dissipating the excess heat. Shaking chills after the fever are your body's attempt to raise its core temperature. Repeated episodes of fever followed by sweating may indicate a serious infection or other illness.

  • Overactive thyroid (hyperthyroidism). Sometimes the thyroid gland produces excess amounts of the hormone thyroxine. This can cause a number of signs and symptoms, including weight loss, a rapid or irregular heartbeat, nervousness and increased sensitivity to heat. It may also cause you to perspire much more than normal.

  • Heart attack. This occurs when a loss of blood supply damages or destroys part of your heart muscle. The signs and symptoms of a heart attack include pressure; fullness or squeezing pain in your chest that lasts for a few minutes or pain that extends beyond your chest to your shoulder, arm or back; shortness of breath; and intense sweating. If you experience these symptoms, get immediate medical care. Every minute counts after a heart attack.

  • Tuberculosis. In 2002, this chronic bacterial infection of the lungs affected more than 15,000 people in the United States. When left untreated, tuberculosis can be fatal. Among its signs and symptoms are a cough, slight fever and night sweats.

  • Malaria. Malaria affects millions of people worldwide. The disease occurs primarily in tropical and subtropical countries, but just over 1,000 new cases are reported each year in the United States, primarily among people returning from other parts of the world. The signs and symptoms are related to the life cycle of the parasite that causes malaria, and may begin anywhere from eight days to one year after you've been infected. Initially, you may have chills, headache, vomiting and nausea, but as your body temperature falls, you begin to sweat profusely. The cycle may recur every 48 to 72 hours.

  • Certain types of cancer. Leukemia and lymphoma can produce unusual sweating patterns.

Decreased or nonexistent sweating (anhidrosis)
Most people worry about excessive sweating. But some people sweat very little or not at all — a condition that can be potentially life-threatening. Factors that may affect your ability to perspire normally include:

  • Certain drugs. Antipsychotic medications used to treat serious mental disorders may interfere with the functioning of the sweat glands.
  • An inherited condition. Children with hypohidrotic ectodermal dysplasia (HED), a rare disorder, are born without sweat glands, which puts them at high risk of death from overheating (hyperthermia) — especially in hot environments. So far scientists have identified two genes that may be responsible for HED.
  • Autonomic neuropathy. This disorder damages the nerves that help control some of the involuntary functions of the autonomic nervous system, which regulates your internal organs, sweat glands and blood pressure. Damage to these nerves can interfere with the activity of your sweat glands, making it hard for your body to maintain its normal temperature.
  • Infections. Severe infections of the sweat glands — such as hidradenitis — may prevent the glands from functioning normally.
  • Burns. Major (third-degree) burns — either from fire, chemicals or electricity — can damage the skin as well as sweat glands, muscle and even bone.
  • Dehydration. This occurs when you don't have enough water in your body to carry on normal functions. You can easily become dehydrated when you work or exercise in hot weather and don't drink enough fluids to replace what you've lost through perspiration. Other common causes of dehydration include persistent vomiting or diarrhea or the use of medications that increase the flow of urine (diuretics). Eventually, you may lose so much fluid that you're no longer able to sweat. Signs and symptoms may include thirst, weakness and confusion. Severe dehydration can be fatal. Older adults and young children are especially at risk.
  • Heatstroke. Like dehydration, heatstroke can occur when you work or exercise strenuously in hot weather and don't drink enough to replace the fluids you've lost. Older adults, people who are obese and children with HED are at high risk of heatstroke. Heatstroke is particularly serious because your body's normal mechanisms for dealing with heat stress, such as sweating, are lost. The main heatstroke signs are a high body temperature — generally greater than 104 F — with hot, dry skin and confusion or even coma.

When to seek medical advice

See your doctor if you suddenly begin to sweat more than usual or experience night sweats for no apparent reason. A cold sweat is usually your body's response to a serious illness, anxiety or severe pain. Seek immediate medical attention for a cold sweat, especially if you have symptoms of lightheadedness or chest and stomach pains.

Also talk to your doctor if you notice a change in body odor — it may be a sign of certain medical conditions. A fruity smell, for example, may be a sign of diabetes and an ammonia smell could indicate liver or kidney disease. In addition, a rare condition known as fish-odor syndrome (trimethylaminuria) causes an odor similar to rotting fish. People with fish-odor syndrome have a defective gene that prevents them from metabolizing trimethylamine (TMA), a natural byproduct of the digestion of foods such as saltwater fish, eggs and liver.

Complications

Complications associated with too much or too little sweating can range from annoying to life-threatening problems. Common complications of excessive sweating include:

  • Fungal nail infections. People who sweat profusely are prone to many types of fungal infections. That's because fungi thrive in warm, moist environments such as sweaty shoes. That's also why you're more likely to get an infection in your toenail than in your fingernail. A nail infection usually begins as a white or yellow spot under the tip of your nail. As the fungal infection spreads deeper, your nail may discolor, thicken and develop crumbling edges. Sometimes your nail may separate from the nail bed, and the skin around it may become red and swollen. You may even detect a slight odor.
  • Athlete's foot. Sometimes sweaty feet just smell bad. That unmistakable foot smell, which occurs when sweat and bacteria mix, may or may not occur along with athlete's foot — a fungal infection that usually begins between your toes and causes your skin to itch, burn and crack. Athlete's foot can also affect the soles and sides of your feet, causing your skin to peel or thicken.
  • Jock itch. This fungal infection causes an itching or burning sensation around your groin. You may also have a red rash on your inner thighs and buttocks. Jock itch is mildly contagious and can spread by contact or shared towels.
  • Bacterial infections and warts. Excessive sweating can contribute to bacterial infections, especially around hair follicles or between your toes. It can also lead to warts — skin growths caused by the human papillomavirus (HPV).
  • Heat rash or prickly heat. This rash occurs when the pores around the sweat glands become blocked. As a result sweat becomes trapped under your skin, causing fine red spots or bumps — usually on your upper back, chest or arms. It most often occurs in hot, humid weather and generally affects babies and young children. Heat rash can also occur if your baby is dressed too warmly or has a fever.

When you stop sweating or don't perspire enough to cool your body, the results can be serious or even fatal. Complications of a lack of perspiration include:

  • Heat exhaustion. This can occur suddenly, often because of excessive exercise and inadequate fluid intake. The signs and symptoms include faintness, nausea, a rapid heartbeat, ashen appearance and hot, dry skin. If you have heat exhaustion, you need to cool down immediately by getting into the shade and drinking cool — not cold — fluids. Heat exhaustion can quickly progress to heatstroke.
  • Heatstroke. Heatstroke can occur when you work or exercise strenuously in hot weather and don't drink enough to replace the fluids you've lost. Older adults, people who are obese and children with HED are at high risk of heatstroke. Heatstroke is particularly serious because your body's normal mechanisms for dealing with heat stress, such as sweating, are lost. In some cases, heatstroke can be fatal. The main signs and symptoms of heatstroke are a high temperature; hot, dry skin; and confusion or even coma.

Treatment

For some people who sweat excessively, the answer may be simple: an over-the-counter (OTC) antiperspirant used on the hands and feet as well as the underarms. Antiperspirants block your sweat ducts with aluminum salts, thereby reducing the amount of perspiration that reaches your skin. Deodorants, which can eliminate odor but not perspiration, turn your skin acidic, which makes it less attractive to bacteria. Although you may have heard stories linking antiperspirants and breast cancer, there's no evidence of such a link.

Antiperspirants can cause irritation or even contact dermatitis — red, swollen, itchy skin. In fact, antiperspirants are the cosmetic product most associated with skin irritation. Deodorants, especially herbal or crystal deodorants, may be less irritating for most people.

If OTC products aren't strong enough, your doctor may suggest a prescription antiperspirant. For more severe problems with sweating, he or she may recommend other treatments, including:

  • Iontophoresis. In this procedure, a dermatologist uses a battery-powered device to deliver a low current of electricity to the affected area. Although iontophoresis is painless and quite safe, it may be no more effective than a topical antiperspirant.
  • Botulinum toxin (Botox). This is the same product that helps smooth facial wrinkles by paralyzing certain muscles. Researchers have discovered that Botox injections are also an effective way to treat severe hyperhidrosis by blocking the nerves that trigger the sweat glands. Botox isn't a cure-all, however. It may take several injections to achieve the desired results, the treatment can be painful, and the results last only about four months. In addition, although Botox stops sweating, it doesn't prevent body odor.
  • Surgery. In rare cases surgery may be an option. If excess sweating occurs just in your armpits, removing the sweat glands may help. Another procedure involves cutting the nerves that carry the messages from the sympathetic nerves to the sweat glands. At one time this was a major operation, requiring large incisions in the chest or back to reach the spinal column, where the nerves are located. You typically stayed in the hospital a week and could expect to spend a month recovering. But today the surgery can be performed using a procedure known as endoscopic thoracic sympathectomy. It requires just three small incisions for a video telescope and small surgical instruments. Although the operation is delicate, it typically requires only a day in the hospital and produces minimal scarring. Following the surgery, sweating on the hands permanently stops. But increased sweating can occur elsewhere on your body, such as your back or the back of your legs.
  • Anticholinergic drugs. If you have generalized sweating, your doctor may prescribe an anticholinergic drug such as glycopyrrolate (Robinul, Robinul-Forte). Anticholinergics work by blocking the actions of acetylcholine, a chemical messenger in your body that helps to stimulate your sweat glands, among other things. Signs and symptoms generally improve in about two weeks. But because acetylcholine acts on a number of different structures in your body, not just your sweat glands, it can have various side effects. These are generally mild. They may include dry mouth, constipation, blurry vision, urinary retention, loss of taste, dizziness and confusion. If you experience diarrhea, rash or hives, or difficulty breathing or swallowing, seek prompt medical help, as these may signal a more serious problem.

Self-care

You can do a number of things on your own to reduce sweating and body odor. The following suggestions may help:

  • Bathe daily. Regular bathing helps keep the number of bacteria on your skin in check.
  • Dry your feet thoroughly after you bathe. Microorganisms thrive in the damp spaces between your toes. Use OTC foot powders to help absorb sweat.
  • Choose shoes and socks made of natural materials. Shoes made of natural materials, such as leather, can help prevent sweaty feet by allowing your feet to breathe.
  • Rotate your shoes. Shoes won't completely dry overnight, so try not to wear the same pair two days in a row if you have trouble with sweaty feet.
  • Wear the right socks. Cotton and wool socks help keep your feet dry because they absorb moisture. When you're active, moisture-wicking athletic socks are a good choice.
  • Change your socks often. Change socks or hose once or twice a day, drying your feet thoroughly each time. Women may try pantyhose with cotton soles.
  • Air your feet. Go barefoot when you can, or at least slip out of your shoes now and then.
  • Choose natural-fiber clothing. Wear natural fabrics, such as cotton, wool and silk, which allow your skin to breathe. When you exercise, you might prefer high-tech fabrics that wick moisture away from your skin.
  • Apply antiperspirants nightly. At bedtime, apply antiperspirants to sweaty palms or soles of the feet. Try perfume-free antiperspirants.
  • Try relaxation techniques. Consider relaxation techniques such as yoga, meditation or biofeedback. These can help you learn to control the stress that triggers perspiration.
  • Change your diet. If foods or beverages cause you to sweat more than usual or your perspiration to smell, consider eliminating caffeinated drinks from your diet as well as foods with strong odors, such as garlic and onions.

To help prevent dehydration, heat exhaustion and heatstroke:

  • Drink plenty of water. Don't wait until you're thirsty to drink water — by the time you feel thirsty, you're already dehydrated. If you're exercising, drink before, during and after you exercise.
  • Exercise when it's cooler. In hot weather, try to exercise early in the morning or in the evening.
  • Choose appropriate clothing. When the weather's warm, wear loose, lightweight, natural-fiber clothing. In cooler temperatures, layer your clothes.
  • Wear a hat. Keep your head covered when exercising or working outdoors in hot weather.
  • Avoid drinking caffeine or alcohol. Both these liquids are dehydrating.
  • Pay attention to your body. Don't ignore the warning signs and symptoms of heat stress, such as muscle cramps, nausea, dizziness or weakness.

  • Night sweats
  • December 09, 2004

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