THURSDAY, July 19 (HealthDay News) -- The U.S. Food and Drug Administration's approval of two new weight-loss drugs within the past month -- the first such medications in 13 years -- won't be a panacea for America's obesity epidemic, health professionals say.

And as the FDA's drug regulators reiterated when approving the two drugs, Qysmia and Belviq, no weight-loss medication should be used without also making lifestyle changes to facilitate weight loss.

"The bottom line is there's no such thing as a magic pill and I hope that individuals do not think by taking this pill that it will ensure long-term weight loss," said Keri Gans, a registered dietitian in New York City. "We need to be reminded that diet and exercise are still critical."

Qysmia, formerly called Qnexa, was approved on Tuesday and is a combination of the weight-loss drug phentermine (brand name Adipex-P, among others) and the anti-seizure medication Topamax (topiramate).

It is only approved for people who are obese (a body mass index, or BMI, of 30 or above) or overweight people (BMI of 27 or higher) and who also suffer from conditions such as high blood pressure, type 2 diabetes or high cholesterol.

Phentermine once was prescribed widely as the "phen" part of the fen-phen weight-loss drug, which was withdrawn from the market in 1997 after it was linked to both high blood pressure in the lungs and heart valve disease. The problems appeared to be related to the "fen," or fenfluramine, part of the combination, not the phentermine.

Qsymia was initially denied FDA approval in 2010 because of potential side effects, including heart palpitations and birth defects -- such as cleft lip in babies -- if taken by pregnant women.

Phentermine is believed to work by controlling appetite and Topamax by speeding up metabolism.

But Topamax also has side effects, including, possibly, numbness in the arms and legs, said Dr. Michael Aziz, an internist at Lenox Hill Hospital, in New York City, who added that having two drugs together could compound the side effects.

The U.S. Food and Drug Administration is stressing that Qsymia not be used by pregnant women. Nor should it be taken by people who have had a recent stroke or unstable heart disease as it can speed up heart rate. Neither should it be taken by people with glaucoma or hyperthyroidism.

And the drug can only be sold via specially certified drug stores.

"The concern is with it being overprescribed," Gans said. "There's the concern that too many people may have access to it when they simply need to make diet modifications and not look for some magic solutions."

The second drug approved in the last month was Belviq (lorcaserin), also for obese adults who have high blood pressure, high cholesterol or type 2 diabetes.

Belviq seems to work by controlling appetite, Aziz said, but in trials it produced limited weight loss.

Belviq may cause serious side effects, including "serotonin syndrome," particularly when taken with certain medicines that increase serotonin levels or activate serotonin receptors, such as drugs used to treat depression and migraine. The drug may also cause problems with attention or memory, the FDA said.

Other common side effects of Belviq in non-diabetic patients include headache, dizziness, fatigue, nausea, dry mouth, and constipation. In patients with diabetes, side effects can include low blood sugar, headache, back pain, cough and fatigue, the FDA said.

The cost of the drug is relatively modest, at least compared to other medications on the market, and may range between $100 and $200 for a month's supply, Aziz said.

But neither drug, despite the splash they've made in the news, is likely to make a significant dent in America's obesity crisis, with two-thirds of the population either overweight or obese.

"The problem that all the drug companies are overlooking is the fact that obesity is really multi-factorial," Aziz said. "It's not only related to diet and exercise but also to hormonal imbalances, stress and lack of sleep."

More information

For more on obesity, visit the U.S. National Library of Medicine.

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