Obesity can be caused by excess food intake, excess sleep, lack of physical work or it may be a hereditary problem. There are tons of ways to get past it. Prominent amongst them are – surgery, liposuction, exercises, controlled food intake and diet pills. Surgery and liposuction are painful, short-term and costly affair plus the results are not same for every individual. Weight loss with exercise and controlled food regimen is natural but time consuming. Diet pills can have short term side effects and are not for long-term use. So, the best way to run over obesity is the combination of diet pills with exercises and restricted food program. Phentermine is such a diet pill which has been in use for treating obesity for short-term since 1959. Phentermine Hydrochloride is a sympathomimetic amine which is prescribed to lower appetite in an obese individual. Till 1997 a cocktail of Phentermine with Fenfluramine known as Fen-Phen was in use to treat obesity. But in 1997 due to reports of pulmonary hypertension and heart valve diseases reported by its users, Fenfluramine was banned in US market but Phentermine was not. Then a new combination of Phentermine with Prozac known as Phen-Pro came into picture. These cocktails were necessary as over a period of time, effect of Phentermine goes on diminishing and the other constituent in these cocktails were used to prolong its effect. FDA has not approved the cocktail but the drugs have FDA approval individually so it is up to a doctor to decide whether one should have the cocktail or not. Side effects like sleeplessness, blurred vision, dry mouth, stomach upset, irritability, and constipation may be visible for the first few days after taking Phentermine. But these side effects are for short term and are mild. Phentermine may also elevate heart rate and blood pressure. However, before going for this drug one should always consult a doctor. A person with heart disease, asthma, blood pressure, allergy or diabetes must tell his doctor about his health history. Children, pregnant women and breast feeding women should consult doctor if they are to use Phentermine. For more than five decades Phentermine has been in use and many obese persons have benefited from it. But use of it without exercise and controlled diet has been futile for reducing weight.