The term is (from the Greek ἀν- (an-) = "without" and ὄρεξις (órexis) = "appetite"), and such drugs are also known as anorexigenic, anorexiant, or appetite suppressant.
Used on a short-term basis clinically to treat obesity, some appetite suppressants are also available over-the-counter. Most common natural appetite suppressants are based on Hoodia, a genus of 13 species in the flowering plant family Apocynaceae, under the subfamily Asclepiadoideae. Several appetite suppressants are based on a mix of natural ingredients, mostly using green tea as its basis, in combination with other plant extracts such as fucoxanthin, found naturally in seaweed. Drugs of this class are frequently stimulants of the phenethylamine family, related to amphetamine (informally known as speed).
The German and Finnish militaries issued amphetamines to soldiers commonly to enhance warfare during the Second World War. Following the war, amphetamines were redirected for use on the civilian market. Indeed, amphetamine itself was sold commercially as an appetite suppressant until it was outlawed in most parts of the world in the late 1950s because of safety issues. Many amphetamines produce side effects, including addiction, tachycardia and hypertension, making prolonged unsupervised use dangerous.
Epidemics of fatal pulmonary hypertension and heart valve damage associated with pharmaceutical anorectic agents have led to the withdrawal of products from the market. This was the case with aminorex in the 1960s, and again in the 1990s with fenfluramine (see: Fen-phen). Likewise, association of the related appetite suppressant phenylpropanolamine with hemorrhagic stroke led the Food and Drug Administration (FDA) to request its withdrawal from the market in the United States in 2000, and similar concerns regarding ephedrine resulted in an FDA ban on its inclusion in dietary supplements in 2004. A Federal judge later overturned this ban in 2005 during a challenge by supplement maker Nutraceuticals. It is also debatable as to whether the ephedrine ban had more to do with its use as a precursor in methamphetamine manufacture rather than health concerns with the ingredient as such.
Weight loss effects of water have been subject to some scientific research. Drinking water prior to each meal may help in appetite suppression. Consumption of 500 mL (approximately 17 fl oz) of water 30 minutes before meals has been correlated with modest weight loss (1–2 kg) in obese men and women over a period of 8 to 12 weeks.
Numerous pharmaceutical compounds are marketed as appetite suppressants.
The following drugs listed as "centrally-acting antiobesity preparations" in the Anatomical Therapeutic Chemical Classification System:
Other compounds with known appetite suppressant activity include: