Benzoyl peroxide is a chemical compound (specifically, an organic peroxide) with structural formula  (C6H5−C(=O)O−)2, often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as two benzoyl (C6H5−C(=O)−, Bz) groups connected by a peroxide (−O−O−). It is a white granular  solid with a faint odour of benzaldehyde, poorly soluble in water but soluble in acetone, ethanol, and many other organic solvents. Benzoyl peroxide is an oxidizer, which is principally used as in the production of polymers.As a bleach, it has been used as a medication and a water disinfectant. In specialized contexts, the name may be abbreviated as BPO. As a medication, benzoyl peroxide is mostly used to treat acne, either alone or in combination with other treatments. Some versions are sold mixed with antibiotics such as clindamycin. It is on the WHO List of Essential Medicines, and, in the US, it is available as an over-the-counter and generic medication. It is also used in dentistry for teeth whitening. Benzoyl peroxide is also used in the plastics industry and for bleaching flour, hair, and textiles. It is also used to remove stubborn stains from dolls and other plastic toys, although some users have claimed that the product has unwanted long-term effects of discolouring the item, particularly with the My Little Pony brand. History
Benzoyl peroxide was first prepared and described by Liebig in 1858.
A somatic symptom disorder, formerly known as a somatoform disorder, is any mental disorder that manifests as physical symptoms that suggest illness or injury, but cannot be explained fully by a general medical condition or by the direct effect of a substance, and are not attributable to another mental disorder (e.g., panic disorder). Somatic symptom disorders, as a group, are included in a number of diagnostic schemes of mental illness, including the Diagnostic and Statistical Manual of Mental Disorders. (Before DSM-5 this disorder was split into somatization disorder and undifferentiated somatoform disorder.) In people who have been diagnosed with a somatic symptom disorder, medical test results are either normal or do not explain the persons symptoms (medically unexplained physical symptoms), and history and physical examination do not indicate the presence of a known medical condition that could cause them, though the DSM-5 cautions that this alone is not sufficient for diagnosis. The patient must also be excessively worried about their symptoms, and this worry must be judged to be out of proportion to the severity of the physical complaints themselves. A diagnosis of somatic symptom disorder requires that the subject have recurring somatic complaints for at least six months.Symptoms are sometimes similar to those of other illnesses and may last for years. Usually, the symptoms begin appearing during adolescence, and patients are diagnosed before the age of 30 years. Symptoms may occur across cultures and gender. Other common symptoms include anxiety and depression.