Body odor

Body odor is the unpleasant smell caused by the mixing of perspiration, or sweat, and bacteria on the skin. Sweat is generally an odorless body secretion. When bacteria multiply on the skin and break down these secretions, however, the resulting by-products may have a strong and disagreeable body odor. This body odor is often due to poor personal hygiene, but excessive perspiration or some other underlying disease are sometimes involved.

Many people find body odor to be disagreeable, and are embarrassed by their own smell, so they take measures to reduce it. These can involve bathing frequently with soap, using a bidet, oral hygiene, and wearing clean clothes, particularly fresh socks and underwear. It is also possible to mask odors, using perfume, or by chewing gum, if bad breath is the concern. Many people find the body odor of Corynebacterium tenuis and C. xerosis in the apocrine sweat of the underarms particularly offensive, so they use antiperspirants or deodorants. Antiperspirants stop the sweat, while deodorants kill or inhibit the offending bacteria. Some individuals find underarm perspiration uncomfortable (or visually offensive if it becomes noticeable on clothing), and use antiperspirants to counter this. Others refrain from using antiperspirants, sometimes due to a viewing perspiration as a natural bodily function that should not be hindered, and sometimes due to naturally low levels of perspiration that can be comfortably managed without antiperspirants. Individuals who choose not to use antiperspirants may or may not choose to use non-antiperspirant deodorants, according to personal preference. Some cultures, such as those in East Asia, and the Jews and Muslims who are required by their faith, have long placed an emphasis on daily bathing. In Europe, during the Middle Ages, bathing was discouraged by the Catholic Church as it was a "pagan" custom and often involved communal bathing and public nudity. Being clean was associated with catching diseases as body filth was thought to provide a protective layer against "vapors". Most Europeans at that time bathed only once or twice yearly. Since body odor often differs between cultures (because diet and hygiene differ between cultures), and because people find unfamiliar body odors to be disagreeable, body odor has long been used by societies to look down on others. 17th century Japanese encountering Europeans for the first time found their odor particularly strong, and likened it to the smell of rancid butter, assigned the name bata-kusai (roughly meaning "stinks of butter") to visiting Europeans at the time. In the period 1910-1920, the American advertising industry initiated the now-familiar strategy of advertisements intended to foster anxiety about social status, and concern about personal deficiencies that could be remedied by buying the advertised product. In 1919, Odo-Ro-No became the first company to use the term "B.O." in an advertisement.

Body odor is influenced by the major histocompatibility complex (MHC) molecules. These are genetically determined and play an important role in immunity of the organism. The vomeronasal organ contains cells sensitive to MHC molecules in a genotype-specific way. Experiments on animals and volunteers shown the potential sexual partners tend to be perceived more attractive if their MHC composition is substantially different. This behavior pattern promotes variability of the immune system of individuals in the population, thus making the population more robust against new diseases.

When someone complains of body odor, the doctor will need more information. Some of the questions he or she might ask include: