You Should Think Twice Before Taking Prescription Diet Pills

You Should Think Twice Before Taking Prescription Diet Pills

Prescription diet pills are a big industry, but these medications are far from the miracle pill that they seem. Here’s why to avoid them!

With products promising everything from faster weight loss to appetite suppression to decreased cravings, prescription weight loss drugs may seem like a long-awaited solution for ever-increasing rates of obesity.

Unfortunately, these medications carry a high risk of side effects, are prohibitively expensive, and may prove addictive when taken at high doses or for long periods of time.

Prescription Obesity Medication In The US

Prescription weight-loss drugs are available for some obese patients with a body mass index (BMI) of 30 kg/m2 or greater.

Most anti-obesity medications are also available to overweight patients with a BMI of 27-30 kg/m2 plus one or more weight-related condition (e.g. type 2 diabetes, high cholesterol).

At this time, there are five prescription obesity medications approved by the FDA for long-term use. They are:

  1. Bupropion-naltrexone (Contrave);
  2. Liraglutide (Saxenda);
  3. Lorcaserin (Belviq);
  4. Orlistat (Xenical);
  5. Phentermine-topiramate (Qsymia).

However, the most popular weight loss medication is an older drug that is only approved for short-term use: phentermine hydrochloride.

American doctors wrote over 6.2 million prescriptions for phentermine in just three years (2008-2011).

Why Avoid Taking Prescription Diet Pills?

If these diet pills are so widely-prescribed, is there any reason not to jump on the bandwagon and ask your doctor for a prescription at your next appointment? Consider these disadvantages first:

1. Side Effects

The first major drawback of diet pills in general, and especially prescription diet pills, is the significant risk of dangerous side effects.

Here’s a summary of side effects caused by the six medications listed above:


This is the most popular prescription weight loss medication and may cause serious heart and lung problems. More specifically, heart valvulopathies and primary pulmonary hypertension.

These reactions are rare, but more common phentermine side effects include:

  • Dry mouth (experienced by over 80% of users);
  • Insomnia;
  • Constipation;
  • Headache;
  • And mood changes.

Combining this medication with other drugs or supplements can also cause serious, even fatal, reactions.

Qsymia (Phentermine-Topiramate)

It has all of the same side effects as phentermine but also carries the risk of additional reactions related to the topiramate. The most worrisome Qsymia side effects are:

  • An increased risk for serious birth defects (cleft lip/palate);
  • Increased heart rate;
  • Suicidal thoughts/actions;
  • And serious eye problems (secondary angle-closure glaucoma).

Contrave (Bupropion-Naltrexone)

It contains different active ingredients, so its side effects list is different. Serious potential reactions to this weight loss medication include:

  • Suicidal (or manic) thoughts or actions;
  • Seizures;
  • Sudden opioid withdrawal;
  • Elevated heart rate or blood pressure;
  • Liver damage/hepatitis;
  • And eye problems.

More common side effects of Contrave include nausea/vomiting, constipation, diarrhea, and headache.

Saxenda (Liraglutide)

This is an injectable weight loss medication. In humans, the medication has been shown to cause severe side effects including:

  • Pancreas or gall bladder problems;
  • Suicidal ideation;
  • Nausea/vomiting;
  • Low blood sugar;
  • Diarrhea;
  • Constipation;
  • And headaches.

However, Saxenda also comes with a black box warning because, based on animal studies, it may increase patients’ risk of medullary thyroid carcinoma (cancer).

Belviq (Lorcaserin)

Like other prescription appetite suppressants, it comes with a long list of side effects. The most common reactions are headache, dizziness, and fatigue.

But Belviq patients should also be monitored for serotonin syndrome, valvular heart disease, mental health changes (including suicidal thoughts), and low blood sugar.

Xenical (Orlistat)

It is the only medication on this list that is not an appetite suppressant and does not affect patients’ hormones or nervous system.

It acts by reducing fat absorption in the gut. As a result, Xenical does not cause the systemic side effects typical of other prescription weight loss medications.

These pills can, however, cause uncomfortable side effects like “flatulence with discharge”, diarrhea, and oily stools. In rare cases, it may also cause liver, kidney or gallbladder problems.

These risks are only exacerbated when a weight loss medication is combined with other substances.

Always tell your prescribing doctor and pharmacist if you take, or have recently taken, any other medications (prescription or OTC), supplements or drugs.

2. Cost

Most prescription weight loss medications are expensive and not covered by medical insurance in many cases.

Qsymia, for example, costs about $200 per month. The prices of Contrave and Belviq are even more outrageous at around $350 per month.

Coupons and discounts can help offset these costs, but the high price points put long-term treatments outside of many people’s reach.

Instead, patients often choose to take phentermine, which only costs about $30 per month – even before coupons, discounts or insurance.

3. Addictive Potential

Last but not least, some of these medications are considered controlled substances because their active ingredient poses a risk for addiction and abuse.

Phentermine, Qsymia, and Belviq are categorized as class IV controlled substances. According to the DEA, class IV substances are “drugs with a low potential for abuse and low risk of dependence”.

Other well-known medications in this drug class include Ambien, Valium, Xanax, and Tramadol.

While recent research indicates that long-term phentermine use probably does not precipitate addiction, first-hand reports of cravings and other withdrawal symptoms may indicate differently. As a result, the drug’s status as a controlled substance remains unchanged.

For all of these reasons, talk with your doctor before starting treatment with a prescription weight loss medication. While these pills are undoubtedly helpful in some cases, they are not a “miracle pill” solution for everyone.

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