There have been many advances in obesity treatment, including life-style modification and pharmacological and surgical treatments. It seems that the most remarkable advances in obesity treatment are those of pharmacological strategies. However, weight loss medications have a long history of development. The FDA has withdrawn anti-obesity drugs such as fenfluramine, dexfenfluramine, and phenylpropylamine due to unwanted side effects. Sibutramine was voluntarily withdrawn from the market, and new drugs such as rimonabant have been suspended in the middle of clinical study due to unacceptable side effects. Last year, the FDA approved two new anti-obesity drugs for the treatment of obesity. Lorcaserin is a selective 5-hydroxytryptamine receptor 2c (5-HT2c) agonist whose pharmacological mechanism of action is similar to those of fenfluramine and dexfenfluramine. However, lorcaserin is specific for 5-HT2c, which is located almost exclusively in the CNS and is not found on heart valves. Three exciting phase 3 clinical trials for lorcaserin have been published recently. Lorcaserin has been shown to successfully result in weight reduction, and the drug was not found to lead to heart disease, as is the case with some other such drugs. Furthermore, the FDA also approved controlled release phentermine/topiramate (PHEN/TPM CR), a drug composed of immediate-release phentermine and controlled-release topiramate. Weight reduction by PHEN/TPM CR is better than any other anti-obesity drugs in the world. Along with this excellent efficacy, however, come painful side effects that clinicians should consider.