The F.D.A. approved the newest prescription weight-loss drug, Qsymia. It’s been 13 quiet years since the last pound-shedding drug Orlistat came out. Qsymia’s approval makes it the second weight-loss drug to hit the market in just a few weeks (Belviq was approved last month). In clinical trials, Qsymia (formerly called Qnexa), from Vivus pharmaceuticals, helped obese individuals lose about 10 percent of their body weight.”Drugs like this are crucial to stemming obesity, which is such a vital issue,” says Michael Roizen, M.D., YouBeauty cofounder and chief wellness officer at the Cleveland Clinic. “We have to do something if we are going to get health costs under control. If this drug helps reverse the trend even a little bit, or at the very least raises awareness of the problem, then it can be extremely valuable.”QUIZ: Is Your Body Healthy?While patients on Qsymia shed twice as much weight as those who took Belviq, outlook for the latest newcomer isn’t all rosy. The once-a-day, time-release capsule combines topiramate, an anti-convulsion medication know to cause birth defects, and phentermine, the half of fen-phen that’s still legal.If this is sounding just a little too familiar, well, it’s not just you.In Vivus’s first attempt to get Qsymia past regulators back in 2010, the F.D.A. issued a letter expressing concerns over the safety of the two main ingredients. Phentermine has been on the market since 1959, but gained notoriety in the 1990s when fen-phen became all the rage—and then all the scourge. After widespread off-label use—which is to say, your aunt/best friend/boss using it to drop a dress size, as opposed to its official purpose to treat clinical obesity—it came to light that fenfluramine could cause fatal heart valve problems. The F.D.A. pulled the bad fen off the market in the fall of 1997. Qsymia will be dispensed only through pharmacies to try to head off abuse.Still, that’s not to say that the “good” phen doesn’t raise concerns of its own.“Medicines and surgery are now cornerstones of obesity treatment,” says YouBeauty Wellness Advisor Beth Ricanati, M.D. “The newest kid on the block is Qsymia, and like its pharmacological predecessors, it has side effects. Most of the other obesity medications on the market have been pulled for safety concerns. Currently, the only other F.D.A.-approved drugs on the market are Xenical and Belviq. These are serious drugs with serious side effects. They are for those with significant obesity and who have medical complications as a result.”MORE: Calorie Restriction, Longer Life & A Magic PillDuring Qsymia’s clinical testing, some patients experienced an increased heart rate, which could lead to other cardiovascular problems, such as increased chance of heart attack or stroke. (Though there is no confirmed direct cause-and-effect.) In order to gain F.D.A. approval, Vivus agreed to conduct further testing to show that Qsymia does not have dangerous cardiovascular side effects. In fact, the company is setting out to show that Qsymia actually improves cardiovascular health, including lowering blood pressure and reducing heart attack and stroke risk.But these tests won’t start until after the drug hits pharmacy shelves.The F.D.A.’s initial review also required Vivus to draw up an evaluation and “mitigation strategy” to address the risks of topiramate. Marketed as Topamax to treat epilepsy and to prevent migraines, the drug is known to increase the chance of children born with cleft lips or palates if women take it during the first trimester of pregnancy. Qsymia will come with a pregnancy warning label.Dr. Roizen contends that it’s too early to tell if women should be wary of the drug and stresses instead its potential: “This could be a powerful aid to help many people get a jump start or get past a plateau on the way to overcoming obesity. And if you take an extra 20-minute walk every time you take this pill, it is likely you’ll lose more weight and be healthier.”MORE: Start Feeling And Looking Younger