Diaphoresis is perspiration (in which sense the name is synonymous with sweating) or, more commonly, excessive perspiration (in which sense the name can be either synonymous with hyperhidrosis or differentiable from it only by clinical criteria involved in narrow specialist senses of the words). A diaphoretic is something (such as a drug) that has the power to cause or increase perspiration.
The skin's sweat glands release a salty fluid, sweat, for evaporative cooling that aids in normal homeostasis (via thermoregulation) and in fever management. Sweating is an essential function and commonly occurs across most of the body's surface, most especially under the arms, on the feet, and on the palms of the hands. There are approximately two to four million sweat glands throughout the body that will become completely active during puberty. Although women tend to have more sweat glands, men's are generally more active.
Diaphoresis is a non-specific symptom or sign, which means that it has many possible causes.
Normal physical causes of diaphoresis include physical exertion, menopause, fever, spicy foods, and high environmental temperature. Strong emotions (anger, fear, anxiety etc.) and remembrance of past trauma can also trigger profuse sweating.
The vast majority of sweat glands in the body are innervated by sympathetic "cholinergic" neurons. Sympathetic postganglionic neurons usually secrete norepinephrine and are named sympathetic adrenergic neurons. However, when sympathetic postganglionic neurons innervate sweat glands they secrete acetylcholine and hence are termed sympathetic "cholinergic" neurons, the only sympathetic postganglionic neurons known to secrete acetylcholine instead of norepinephrine.
Diaphoresis may be associated with some abnormal conditions, such as hyperthyroidism and shock. If it is accompanied by unexplained weight loss or fever or by palpitations, shortness of breath, or chest discomfort, it suggests serious illness.
Diaphoresis is also seen in an acute myocardial infarction (heart attack), from the increased firing of the sympathetic nervous system, and is frequent in serotonin syndrome. Diaphoresis can also be caused by many types of infections, often accompanied by fever and/or chills. Most infections can cause some degree of diaphoresis and it is a very common symptom in some serious infections such as malaria and tuberculosis. In addition, pneumothorax can cause diaphoresis with splinting of the chest wall. Neuroleptic malignant syndrome and other malignant diseases (e.g. leukemias) can also cause diaphoresis.
Drugs (including caffeine, morphine, alcohol, and certain antipsychotics) may be causes, as well as withdrawal from alcohol, benzodiazepines, nonbenzodiazepines or narcotic painkiller dependencies. Sympathetic nervous system stimulants such as cocaine and amphetamines have also been associated with diaphoresis. Diaphoresis due to ectopic catecholamine is a classic symptom of a pheochromocytoma, a rare tumor of the adrenal gland. Acetylcholinesterase inhibitors (e.g. some insecticides) also cause contraction of sweat gland smooth muscle leading to diaphoresis.
Mercury is well known for its use as a diaphoretic, and was widely used in the 19th and early 20th century by physicians to "purge" the body of an illness. However, due to the high toxicity of mercury, secondary symptoms would manifest which were erroneously attributed to the former disease which was being treated with mercurials.
Infantile acrodynia (childhood mercury poisoning) is characterized by excessive perspiration. A clinician should immediately consider acrodynia in an afebrile child who is sweating profusely.
The most commonly experienced symptom of excessive sweating is body odor. Odor develops due to yeast or bacteria that live naturally in the skin. As the skin becomes moist and mixes with these, odor is released. Another explanation is when the apocrine gland release sweat directly into the tubule of the glands. When placed under stress, these tubules contract and sweat is pushed to the surface of the skin. Bacteria will begin to break down and odor is released. Medications that are used for other treatments and diet will also affect odor. Medical conditions like kidney failure and diabetic ketoacidosis will have the same effect. Areas that produce excessive sweat usually appear pink or white, but, in severe cases, may appear cracked, scaly, and soft.
When diaphoresis is pathologic, the underlying cause should be treated. When the cause is menopause, the woman may wish to ask her physician about estrogen replacement. Once potential pathological and environmental causes of diaphoresis are ruled out by a physician, it is more accurately referred to as hyperhidrosis.
Medications such as topical antiperspirants, iontophoresis, Botox and surgery have been tried to treat hyperhidrosis. Treatment of diaphoresis most often begins at home with over-the-counter antiperspirants. These contain certain compounds that block the sweat pores and reduce the amount of sweat that can reach the skin. Another typical over-the-counter product is deodorant. It eliminates odor, but does not block the sweat pores like antiperspirants. They work by turning the skin to an acidic state which is not a desired place for bacteria. Many antiperspirants will contain deodorants. If these products are not effective, prescription strength versions can be prescribed.
If the typical over-the-counter treatments are not effective, a physician can prescribe treatment based on a person's age, overall health, the cause and severity of the condition, and a patient's tolerance. Some regimens are as simple as placing topical solutions on the area at night, while others like the use of Botox or iontophoresis requires more tolerance. Botox injections help inhibit nerve impulses and are injected directly into the area that is affected most by sweating, while iontophoresis is the application of electric currents to the area. Some oral medications called anticholinergics have been found to reduce the amount of sweating as well. If all previous methods fail to work to the patients expectancy, sympathectomy surgery can be performed. This procedure can be used to control sweating on the hands and feet and works by destroying portions of the nerve supply to the sweat glands in these areas.
In some people, the body's mechanism for cooling itself is overactive, so overactive that they may sweat four or five times more than is necessary, or normal. Millions of people are affected by this condition, but more than half never receive treatment due to embarrassment or lack of awareness. While it most commonly affects the armpits, feet, and hands, it is possible for someone to experience this condition over their whole body. The face is another common area for hyperhidrosis to be an issue. Sweating uncontrollably is not always expected and may be embarrassing to sufferers of the condition. It can cause both physiological and emotional problems in patients. It is generally an inherited problem that is found in each ethnic group. It is not life-threatening, but it is threatening to a person's quality of life. A treatment modality is clipping of the sympathic nerve at the level of T4 by thoracoscopic means.
While many persons with diaphoresis issues are experiencing an overproduction of sweat, an absence of sweat is also possible and can be harmful. The condition, anhidrosis or hypohidrosis, lowers the body's ability to sweat and remove excess heat from the body. It causes heat exhaustion when experienced throughout the body. Symptoms of this condition include dizziness, flushing, muscle weakness, and little or no perspiration. Unaffected areas may try to compensate by producing more perspiration, so it's possible to sweat profusely on one part of the body and very little or not at all on another.
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