Morgellons is poorly understood but the general medical consensus is that it is a form of delusional parasitosis in which individuals have some form of actual skin condition that they believe contains some kind of fibers.

Morgellons (/mɔː(ɹ)ˈdʒɛlənz/) is the informal name of a self-diagnosed skin condition in which individuals have sores that they believe contain some kind of fibers. Morgellons is poorly understood but the general medical consensus is that it is a form of delusional parasitosis; the sores are the result of compulsive scratching, and the fibers, when analysed, turn out to originate from textiles.

The name was coined in 2002 by Mary Leitao, a mother who rejected the medical diagnosis of her son's delusional parasitosis. She revived it from a letter written by a physician in the mid-17th century. Leitao and others involved in her Morgellons Research Foundation successfully lobbied members of the U.S. Congress and the U.S. Centers for Disease Control and Prevention (CDC) to investigate the condition in 2006. CDC researchers issued the results of their multi-year study in January 2012, indicating that there were no disease organisms present in people with Morgellons and that the fibers found were likely cotton, and concluded that the condition was "similar to more commonly recognized conditions such as delusional infestation".

Treatment of secondary forms of delusional parasitosis are addressed by treating the primary associated psychological or physical condition. The primary form is treated much as other delusional disorders and schizophrenia. In the past, pimozide was the drug of choice when selecting from the typical antipsychotics. Currently, atypical antipsychotics such as olanzapine or risperidone are used as first line treatment.

However, it is also characteristic that sufferers will reject the diagnosis of delusional parasitosis by medical professionals, and very few are willing to be treated, despite demonstrable efficacy of treatment.

Delusional parasitosis, also known as delusional infestation or Ekbom's syndrome, is a delusional disorder in which individuals incorrectly believe they are infested with parasites, insects, or bugs, whereas in reality no such infestation is present. Individuals with delusional parasitosis usually report tactile hallucinations known as formication, a sensation resembling insects crawling on or under the skin.

Delusional parasitosis is a mental disorder characterized by a fixed, false belief that a skin infestation exists, which is in contrast to cases of actual parasitosis, such as scabies and infestation with "Demodex", in which a skin infestation is present and identifiable by a physician through physical examination or laboratory tests.

The alternative name, Ekbom's syndrome, was named after Swedish neurologist Karl-Axel Ekbom, who published seminal accounts of the disease in 1937 and 1938. It is differentiated from Willis-Ekbom Disease (WED), another name for restless legs syndrome. Morgellons is another form of this condition, with nonspecific "fibers" as the infective agent.