All About Prescription Diet Pills

All About Prescription Diet Pills


Update: Jul 10, 2024

Your questions answered about prescription diet pills, including the most frequently asked: Can I get prescription diet pills?

Let’s begin by pointing out that the best way to lose weight is to eat healthy, nutritious, portion-controlled meals and exercise regularly. Not a diet, but instead a lifestyle change. That’s what any good doctor will tell you. But that’s apparently not working (or being worked on, rather) for more than a third of American adults; obesity is an epidemic in the U.S.

Obese and Overweight America

You’re considered overweight if your body mass index (BMI) is between 25 and 30, and obese if it’s over 30. The way your BMI is calculated is fairly uncomplicated—essentially it’s the measure of your body fat based on your height and weight. [1]

According to the Centers for Disease Control (CDC), nearly 37 percent of adult Americans are obese. That’s the average. Some groups are more obese than others, like middle-aged (40 to 59) women. [2]

But we know ourselves and our bodies pretty well, and it doesn’t take much calculation to know if we are a little overweight, obese or morbidly so; the latter if you are 100 pounds over your ideal body weight or have a BMI of 40 or more, or if you have a BMI over 35 with health problems like high blood pressure or diabetes, which are most likely directly linked to obesity. It’s all connected.

What are Prescription Diet Pills?

For starters, these drugs are approved by the Food and Drug Administration (FDA). Of the handful of drugs that have been approved, they work as appetite suppressants (or make you feel like you’re full after eating even a small meal) or are drugs that block fat absorption from the foods you eat.

There are dozens, if not hundreds, of dietary supplements on the market that claim to do the same. The difference? Approved drugs must pass rigorous testing before getting the FDA blessing, and dietary supplements do not. In fact, a supplement can simply say it helps to help suppress appetite, for example, and then make sure to add that its claim has not been evaluated, much less approved by the FDA, that it’s not a drug and isn’t intended to treat anything, including being overweight or obese. Shaking your head? Yeah, me, too.

Who is Prescribed Prescription Diet Pills?

According to the National Institute of Diabetes and Digestive and Kidney Diseases, people who are overweight, obese, or morbidly obese, and have obesity-related health problems are candidates for prescribed diet medications, including one drug that is injected. Health problems like high blood pressure, diabetes, heart disease, stroke, some cancers, sleep apnea, pain in the joints from carrying that weight (osteoarthritis) and even diseases of the liver and kidneys related to being obese, might induce a physician to recommend diet, exercise, and an approved weight-loss drug. [3]

The Five FDA-Approved Diet Drugs

Since the 1950’s – probably long before then – American women in particular took you-name-it diet pills in a desperate effort to stay thin; mostly dangerous and addictive amphetamines. In 1991, the FDA banned more than 100 diet drug ingredients, and I have written about banned FDA substances and weight-loss supplements before. [4]

As proof, the Fen-Phen mania in the ‘90s: women were eating this stuff like candy to lose weight, and lose weight they did. But about 30 percent developed what could have been possibly fatal heart valve problems.

In fact:

[su_quote cite=”Mayo Clinic” url=”″]In July (1997), researchers at the Mayo Clinic and Mayo Foundation reported 24 cases of rare valvular disease in women who took the “fen-phen” combination therapy. FDA alerted medical doctors that it had received nine additional reports of the same type, and requested all health care professionals to report any such cases to the agency’s MedWatch program … or to the respective pharmaceutical manufacturers. [/su_quote] [5]

More than sixty other cases were reported almost immediately after the request was made. But it took the FDA until 1997 to ban the drug. [6]

So there’s not a good track record for federal regulators, manufacturers, and people using – and abusing – drugs and supplements to lose weight. In 1999, the FDA did finally approve a weight-loss drug. And in the past five years, approved four more. There are only a total of five prescription diet drugs approved by the FDA.

This list will begin with each drug’s brand name:

  1. Xenical, approved in 1999—many know it as Orlistat—is the same ingredient found in the over-the-counter diet pill called Alli, albeit on the shelves, this drug is just a smaller dose. [7]
  2. Belviq The drug is lorcaserin, and was approved in 2012. Previously, a diet drug hadn’t been approved by the FDA in almost 13 years. [8]
  3. Qsymia Approved in 2012, it’s another combo drug which consists of phentermine and topiramate. The former may sound familiar; phentermine is the FDA-approved, prescription-only stimulant that is illegally sold all over the Internet. [9]
  4. Saxenda. The drug is liraglutide, which is the only one of the five that is injected. Approved in 2014, it is also marketed for type 2 diabetes. [10]
  5. Contrave, approved in 2014, is a combination of the antidepressant bupropion and the drug naltrexone, used to treat alcohol and drug dependence. [11] [12]

How (and If) Each Diet Drug Works

A 2016 study published in the Journal of the American Medical Association (JAMA), which calculated the findings’ average of more than two dozen clinical trials with nearly 29,000 participants, showed that while each drug had a measure of efficacy, some are better than others in producing weight loss. [13] [14]


This drug works in your gut to reduce the amount of fat your body absorbs from ingested food. This drug was the least effective weight loss medication in the study, with an average 5.5 pound weight loss. And, the NIH conclusion said “…the modest efficacy, undesirable adverse effects, and serious health risks combine to highlight the deficiencies of orlistat and underscore the pressing need for other obesity drug options.” [14]


Belviq works in your brain to make you “feel” full by acting on serotonin receptors. In the study, Belviq was found to be among the least effective; participants lost an average 7 pounds in a year. The NIH is not convinced of the drug’s potential rewards-versus-risks payoff. [14]


A mix of two medications—phentermine, which decreases appetite, and topiramate, which is used to treat seizures or migraine headaches—Qsymia may make you less hungry or feel full even when you’ve eaten a small meal. And this is the drug where people lost the most weight (which is not surprising, since it contains a powerful stimulant that acts as an appetite suppressant.) In the study people lost an average of 20 pounds. For the NIH, it’s the complementary nature of the two-drug combination that make it effective. [14]


Like every drug that follows, this one is supposed to be used with a reduced-calorie diet and exercise or activity plan to help overweight and obese people lose weight and keep from gaining it back. This drug may suppress your appetite or make you feel full sooner (the common term among research reports is “satiety”). At a lower dose under a different name, it’s known as Victoza, FDA-approved to treat type 2 diabetes. In the study published in JAMA, participants lost an average of 11.5 pounds in a year. And, an NIH-published study says, “with diet and exercise, to provide sustained weight loss over 2 years, greater efficacy compared to orlistat.” [15]


A mix of two medications (naltrexone, which is used to treat alcohol and drug dependence, and bupropion, which is used to treat depression or help people quit smoking), Contrave may make you feel less hungry or full sooner. In the 2016 study, people who used this drug for a year lost an average of 11 pounds. The NIH says:

Contrave may serve as a valuable treatment adjunct to lifestyle modifications by promoting satiety, reducing feeding, enhancing energy expenditure, and ultimately helping patients achieve weight loss goals. [16]

Proceed with Caution; Side Effects and Warnings

First, a note from me: tell your doctor about any and all supplements you take, including herbs in capsule or even tea form.

Just because the FDA has given its stamp of approval, doesn’t mean there can’t be interaction effects with these drugs, some serious, even deadly. The NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) list of side effects for the five approved drugs runs the range from the uncomfortable to the frightening.


All about the tummy, Orlistat side effects are mostly limited to gas, loose stools, stomach ache, diarrhea and the like, so rather unpleasant. This drug absorbs a quarter of the fats you ingest so if you eat too much fat, the gastrointestinal symptoms become worse. Nutrients may be lost with Orlistat, so a good multivitamin is recommended.


Some typical gastrointestinal effects and a number of other side effects that on their own may not be deal-breakers. What is a potential problem is drug interactions, so make sure your doctor knows exactly what you take: over-the-counter remedies to herbs, and supplements.


Another possibly very effective diet pill but with a lot of side effects; some you maybe can live with, some you cannot, the latter if you are pregnant or even planning on having children as this drug can cause birth defects. Other side effects include constipation, dizziness, dry mouth taste changes, extremity tingling and insomnia. Plus, if you have glaucoma or have had issues with mood or suffered heart attack or stroke, have abnormal heart rhythm, or kidney disease, all of these may rule this drug out as a weight loss medication for you.


Mild and moderate side effects include nausea, diarrhea, constipation, abdominal pain and headache. There is some research that shows a rare tumor found in animals in clinical studies. But the NIH has not put this as a warning. In other words, no big scary red flags.


Side effects that include all of the above and many more moderate to uncomfortable to precarious side effects like dizziness, increased blood pressure, increased heart rate, insomnia and liver damage. Plus, an all-caps warning: “MAY INCREASE SUICIDAL THOUGHTS OR ACTIONS.” There’s also contraindications for people who have a number of conditions ranging from anorexia to seizures. This med could be very effective, but could also be potentially risky.

Bottom Line: Can (or Should) You Get Prescription Diet Pills?

If you fit the criteria—overweight with health problems or obese—the answer is probably yes. But which drug, if any, will depend.

For example, if you already take an antidepressant or have a history of drug dependency, Contrave isn’t for you. And if you are pregnant or ever want to have children, Qsymia can cause birth defects, so that drug might be better suited for post-menopausal women or men. Your doctor is the person who’ll know best, if they have a complete medical history, a list of all your other meds and, most importantly, your honesty.

Remember, there’s no magic pill. Diet drugs are an aid. Even with diet pills, it’s best to change your lifestyle if you want to live a longer life; eat as healthy as you can, control your portions, and exercise regularly.

Obesity is not only a public health crisis; it can lead to the three major killers of American adults: cardiovascular disease, cancer, and diabetes. [14]

It’s a disease, and if you need help to treat it, talk to your doctor. They’ll help you decide.

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