Bad Body Odor – Causes of Foul, Fishy and Fecal Body Smell

People often refer to offensive smells coming from the body as body odor. However, the term “body odor”, in its true sense, does not have any positive or negative connotation. It simply refers to the natural smell of the skin, when a person is not masking it with artificial perfumes. In this sense, body odor is a mix of natural odors that emanate from different regions of the body. In addition to odors emanating from the skin, odors from orifices such as the vagina, ear, mouth, and urethra also contribute to the overall body odor. Body odor could be pleasant or bad under different conditions.

Sources of Body Odor

The skin does not emit any odors by itself. The odor attributed to the skin is caused by sweat, dirt, dust, and topical applications such as creams and lotions. Sweat is the most common source of body odor. It is present even when other odor-contributing substances on the skin are washed away.

The characteristics of body odor change with the amount of sweat produced. For example, one is more likely to have bad body odor due to profuse sweating in hot and humid summers. The sweat is produced by two distinct kinds of sweat glands in the skin: apocrine glands and eccrine glands.

Apocrine glands

Apocrine sweat glands are located in the hairy areas of the body, such as the axilla, groin, and scalp. The sweat produced by the apocrine sweat glands is more viscous than the sweat produced by eccrine glands. This is due to the presence to fatty substances in the sweat produced by the apocrine glands. The exact function of the sweat produced by the apocrine glands is not known.

It is suggested that this sweat may play a role in maintaining the texture of the hair. It is also possible that the apocrine sweat glands are actually scent glands. In fact, secretions from the apocrine sweat glands increase after puberty. This is also the time when secondary sexual characteristics in males and females begin to develop.

Hormonal and emotional changes also influence the production of sweat from the apocrine glands. Sweat production from the apocrine glands is less when compared to the amount of sweat produced by the eccrine glands.

Eccrine glands

Eccrine sweat glands are located in the skin throughout the body. These glands can produce a significant amount of sweat. The main function of sweat production by eccrine glands is thermoregulation. In hot weather, sweat production by eccrine glands increases as the body temperature rises. In these circumstances, sweating cools down the surface of the body.

The composition of sweat produced by the eccrine glands is different from that of the sweat produced by apocrine glands. Sweat from eccrine glands contains water, urea, potassium lactate, sodium, heavy metals, citrulline, proteolytic enzymes, organic compounds, aspartic acid, ornithine, and ammonia. The production of sweat from eccrine glands increases with ambient temperature and physical exertion.

Causes of Bad Body Odor

When the body odor becomes offensive, it is referred to as bad body odor. There are many different kinds of bad body odors. The causes of bad body odor also vary widely. The source of offensive body odor could either be the skin or any of the orifices. The foul smell may arise from different regions of the body, such as the groin, armpits, mouth, foot, and ears.


The skin itself is odorless. The sweat produced by the apocrine and eccrine glands also does not produce a bad odor on its own. However, when the substances contained in the sweat are broken down or transformed through bacterial action, bad odor may be produced. Bacteria are part of the normal flora on the skin. However, they thrive in areas of the skin that are warm and moist.

Therefore, there is a higher likelihood of bad odor emanating from such regions of the skin. Increased sweating (technically referred to as hyperhidrosis) also increases the likelihood of having bad body odor since it stimulates more bacterial activity. Individuals who chronically suffer from hyperhidrosis may have bad body odor that is persistent. Technically, persistent bad body odor that is associated with excessive sweating is referred to as bromhidrosis.

Read more on armpit odor.

Medical conditions

Bad body odor may also be caused by certain medical conditions. For example, hepatic failure, renal failure, starvation, and diabetes could cause production of different types of body odors. Hepatic (liver) failure may give rise to a mousy or musty odor due to methyl mercaptan. Renal (kidney) failure may result in the production of a fishy odor due to accumulation of ammonia. Increased fat breakdown into acetone during starvation and diabetes may result in the production of a disagreeable fruity smell.

Foul, Fishy and Fecal Body Odor

Bad body odor can assume many different characteristics, making it difficult to describe it properly. Three terms that are commonly used to describe bad body odors are foul, fishy and fecal odors.

Foul body odor

The term “foul odor” is a non-specific, umbrella term used to describe all types of bad odors. The term “foul odor” may refer to mousy, musty, putrid, fishy, sweet, fecal or fetid odors. Probable causes of a foul body odor include poor hygiene, bromhidrosis, smoking, dirty clothing, consumption of alcohol, halitosis (bad breath), skin infections, topical applications, bowel incontinence, urinary incontinence, and abnormal discharges from various orifices such as the vagina, penis, nose, and ear. The term “foul body odor” may also be used to describe bad odors caused by medical conditions.

Fishy body odor

Unlike the umbrella term “foul body odor”, the term “fishy body odor” describes a specific type of odor. This is the smell that is typical of ammonia. A fishy body odor is likely to occur when the concentration of ammonia in the body increases. The reason for increased ammonia is usually a kidney disease in which urea (a breakdown product of protein metabolism) is not excreted well enough through the urine. This leads to increased urea concentration in the blood (technically referred to as uremia) and a fishy breath.

A fishy body odor in women has also been associated with menstruation. However, this is more likely to occur due to poor hygiene during menstruation rather than menstruation itself. Bacterial action on menstrual blood clots or bacterial infections of the vagina may be the cause of the fishy body odor in these cases. Infections of the urinary tract may also cause a fishy odor in both males and females. Post-micturition dribble and urinary incontinence are other potential causes of fishy body odor in both the sexes.

Fecal body odor

Fecal body odor may be caused by the presence of residual fecal matter on the skin or clothes. Fecal incontinence, diarrhea, and inadequate cleaning up after passing stools are likely reasons for a fecal body odor. Mentally ill patients and debilitated elderly individuals who cannot use the toilet by themselves are more likely to have a fecal body odor. Gastrocolic fistula is a medical condition that can cause fecal body odor as well as foul smelling breath that resembles the smell of feces.

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