Candida hypersensitivity

Candida hypersensitivity is a pseudoscientific disease promoted by William G. Crook, M.D. It is spuriously claimed that chronic yeast infections are responsible for many common disorders and non-specific symptoms including fatigue, weight gain, constipation, dizziness, muscle and joint pain, asthma, and others.
Background.
"Candida albicans" is a fungus that colonizes a large majority of the population (meaning it is present in the body but not causing an infection or any problems). Under certain conditions, however, it can cause an infection. The most common manifestations are thrush (a superficial "Candida" infection in the mouth) and vaginitis, also commonly referred to as a yeast infection. "Candida" can also cause serious systemic infection, but this is almost always restricted to those with compromised immune systems, such as patients undergoing chemotherapy or with advanced AIDS.
Symptoms.
After reading publications by C. Orian Truss, M.D., Crook proposed the idea that a condition he termed systemic candidiasis, or Candida hypersensitivity, was responsible for a long list of common conditions and non-specific symptoms including fatigue, asthma, psoriasis, sexual dysfunction, and many others. The list of symptoms is similar to that of multiple chemical sensitivity. Many patients presenting with symptoms of environmental sensitivity claim to suffer from multiple "fashionable" syndromes.
Criticism.
The American Academy of Allergy, Asthma, and Immunology strongly criticized the concept of "candidiasis hypersensitivity syndrome" and the diagnostic and treatment approaches its proponents use. AAAAI's position statement concludes: (1) the concept of candidiasis hypersensitivity is speculative and unproven; (2) its basic elements would apply to almost all sick patients at some time because its supposed symptoms are essentially universal; (3) overuse of oral antifungal agents could lead to the development of resistant germs that could menace others; (4) adverse effects of oral antifungal agents are rare, but some inevitably will occur; and (5) neither patients nor doctors can determine effectiveness (as opposed to coincidence) without controlled trials. Because allergic symptoms can be influenced by many factors, including emotions, experiments must be designed to separate the effects of the procedure being tested from the effects of other factors.
By 2005, scientists were taking note of "a large pseudoscientific cult" that had developed around the topic of yeast infections, with claims that up to one in three people were affected by yeast-related illnesses including Candida hypersensitivity. 
Legal action.
Some practitioners of alternative medicine have promoted dietary supplements as supposed cures for this non-existent illness, rendering themselves liable to prosecution. In 1990, alternative health vendor Nature's Way signed a FTC consent agreement not to misrepresent in advertising any self-diagnostic test concerning yeast conditions or to make any unsubstantiated representation concerning any food or supplement's ability to control yeast conditions, with a fine of US$30,000 payable to the National Institutes of Health for research in genuine candidiasis.