Anorexia (symptom)

Anorexia (deriving from the Greek "α(ν)-" (a(n)-, a prefix that denotes absence) + "όρεξη" (orexe) = appetite) is the decreased sensation of appetite. While the term in non-scientific publications is often used interchangeably with anorexia nervosa, many possible causes exist for a decreased appetite, some of which may be harmless, while others indicate a serious clinical condition, or pose a significant risk.

Clinically important causes

 * Acute radiation syndrome
 * Acute viral hepatitis
 * Addison's disease
 * Atypical pneumonia (mycoplasma)
 * AIDS
 * Anorexia nervosa
 * Anxiety disorder
 * Cancer
 * Chronic renal failure
 * Congestive heart failure, perhaps due to congestion of the liver with venous blood
 * Crohn's disease
 * Dementia
 * Depression
 * Hypervitaminosis D
 * Metabolic disorders, particularly urea cycle disorders
 * Sickness behavior
 * Superior mesenteric artery syndrome
 * Tuberculosis
 * Thalassemia
 * Ulcerative colitis
 * Zinc deficiency

Drugs

 * Amphetamine (Adderall), dextroamphetamine (Dexedrine & Dextrostat)
 * Antidepressants can have anorexia as a side effect
 * Byetta, a Type II Diabetes drug, will cause moderate nausea and loss of appetite
 * Dextromethylphenidate (Focalin)
 * Abrupt cessation of appetite-increasing drugs, such as cannabis and corticosteroids
 * Methamphetamine (Desoxyn) (treatment of ADD & ADHD and narcolepsy)
 * Methylphenidate (Ritalin & Concerta)
 * Chemicals that are members of the phenethylamine group. (Individuals with anorexia nervosa may seek them to suppress appetite)
 * Stimulants
 * Topiramate (Topamax) (as a side effect)
 * Other drugs may be used to intentionally cause anorexia in order to help a patient preoperative fasting prior to general anesthesia. It is important to avoid food before surgery to mitigate the risk of pulmonary aspiration, which can be fatal.
 * Opiates act upon the digestive system and can reduce the physical sensation of hunger in the same way that they reduce physical sensations of pain. They also frequently cause delayed gastric emptying (gastroparesis) and can sometimes lead to changes in metabolism with long-term use.

Other

 * During the post-operative recovery period for a tonsillectomy or adenoidectomy, it is common for adult patients to experience a lack of appetite until their throat significantly heals (usually between 10-14 days).
 * Altitude sickness
 * Significant emotional pain caused by an event (rather than a mental disorder) can cause an individual to temporarily lose all interest in food