Anorectic drugs are also known as diet pills. These types of drugs have replaced diet pills containing amphetamines. These types of drugs produce some amphetamine-like effects such as loss of appetite, mental alertness, feelings of exhilaration, and increased heart rate. Not all people who have taken anorectic drugs have had these types of side effects. Of these diet pills, phentermine is the most widely prescribed and most frequently encountered on the street. Pulmonary hypertension and heart valve damage associated with pharmaceutical anorectic agents have led to these drugs being taken off the market.