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Phentermine

How it works: Curbs your appetite.

Your doctor may prescribe this under the names Adipex or Suprenza.

Approved for long-term use? No. It's approved for short-term use (a few weeks) only.

Side effects can be serious, such as raising your blood pressure or causing heart palpitations, restlessness, dizziness, tremor, insomnia, shortness of breath, chest pain, and trouble doing activities you've been able to do.

Phentermine may make you drowsy, hampering your ability to drive or operate machinery. As with some other appetite suppressants, there's a risk of becoming dependent upon the drug.

Less serious side effects include dry mouth, unpleasant taste, diarrhea, constipation, and vomiting.

Don't take it late in the evening, as it may cause insomnia.

If you take insulin for diabetes, let your doctor know before you take phentermine, as you may need to adjust your insulin dose.

You should not take phentermine if you have a history of heart disease, stroke, congestive heart failure, or uncontrolled high blood pressure. You also shouldn't take it if you have glaucoma, hyperthyroidism, or a history of drug abuse, or if you are pregnant or nursing.

What else you should know: Phentermine is an amphetamine. Because of the risk of addiction or abuse, such stimulant drugs are "controlled substances," which means they need a special type of prescription.

Qsymia

How it works: Curbs your appetite.

Qsymia combines phentermine with the seizure/migraine drug topiramate. Topiramate causes weight loss in several ways, including helping you feel full, making foods taste less appealing, and burning more calories.

Approved for long-term use? Yes. Qsymia has much lower amounts of phentermine and topiramate than when these drugs are given alone.

Side effects: The most common side effects are tingling hands and feet, dizziness, altered sense of taste, insomnia, constipation, and dry mouth.

Serious side effects include certain birth defects (cleft lip and cleft palate), faster heart rate, suicidal thoughts or actions, and eye problems that could lead to permanent vision loss if not treated.

Women who might become pregnant should get a pregnancy test before taking Qsymia, and should use birth control and get monthly pregnancy tests while on the drug.

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Weight Loss Basics

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Is Your Weight Loss Goal Realistic?

Learn why losing weight slowly is best for long-term results. Discover how to adopt new behaviors, like eating less and exercising more, to boost weight loss.

How to Lose Weight Fast

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Choosing a Weight Loss Program

Learn what to look for when selecting a weight loss program. Discover how to stick with the program once you get going.

Get the Truth About Fad Diets

Get the real facts about fad diets, and learn some healthy weight loss strategies that really work.

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Review All Popular Diet Plans A-Z

Which diet plan is right for you? See reviews of all the popular plans.

Diet Pills

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Herbal Weight Loss Supplements

Because of the uncertainty of the ingredients in weight loss supplements, the FDA strongly recommends that you talk to your health care provider before trying them.

Weight Loss Strategies

Whether it's keeping the weight off or managing cravings, get tips for reaching and keeping your weight loss goals. 

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Top 10 Habits That Can Help You Lose Weight

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These tools will help you assess your weight, track your food calories and activity calories burned, and learn about portion sizes. 

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Portion control is a critical part of successful weight loss and weight management. The WebMD Portion Size Plate gives you easy-to-understand guidelines to help you avoid some common portion-size pitfalls.

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