Prescription Weight Loss Drugs: What Works, Risks & How to Choose

Did you ever wonder why some people seem to shed pounds with a single prescription while others struggle with diet alone? The answer often lies in the type of medication they’re using, how it’s combined with lifestyle changes, and whether they follow safety guidelines.

In the U.S., the FDA currently approves a handful of oral and injectable drugs specifically for weight loss. The most talked‑about ones include phentermine, liraglutide (Saxenda), the combination of bupropion/naltrexone (Contrave), and orlistat (Xenical). Each works differently, so knowing what to expect can help you pick the right option.

How the Main Prescription Options Work

Phentermine is an appetite suppressant that targets the brain’s reward centers. It’s usually prescribed for short‑term use (up to 12 weeks) and can give a noticeable drop in hunger. However, it may cause jitteriness, increased heart rate, or insomnia, especially if you take it late in the day.

Liraglutide is an injectable GLP‑1 receptor agonist originally used for diabetes. At a higher dose, it slows stomach emptying and tells the brain you’re full. People on Saxenda often report steady weight loss without the “crash” feeling of stimulants, but you need a weekly injection and may experience nausea during the first few weeks.

The bupropion/naltrexone combo works on both appetite and reward pathways. Bupropion lifts dopamine levels, while naltrexone blocks opioid receptors that can trigger cravings. This dual action can be helpful for those who binge eat, but it may raise blood pressure, so regular monitoring is key.

Orlistat is a lipase inhibitor that prevents about 30% of dietary fat from being absorbed. It’s taken with meals containing fat, and the effect is visible within days. The downside? Some users experience oily spotting or urgent bowel movements, so a low‑fat diet is essential while on the drug.

Safety Tips and When to Talk to a Doctor

Never start a prescription weight loss drug without a medical assessment. Your doctor will check your BMI, any existing conditions (like heart disease or thyroid issues), and potential drug interactions. For example, phentermine isn’t recommended if you have uncontrolled hypertension, and GLP‑1 drugs can interact with certain antibiotics.

Keep an eye on side effects. Mild nausea, headache, or dry mouth are common, but severe symptoms—chest pain, rapid heartbeat, severe depression—require immediate medical attention. Tracking your progress in a simple notebook (weight, hunger levels, any side effects) can help your provider adjust the dose or switch meds if needed.

Combine medication with realistic lifestyle changes. A prescription is not a magic bullet; most studies show the best results when you add a balanced diet and regular activity. Even a 30‑minute walk a few times a week can boost the drug’s effectiveness and improve your overall health.

Finally, consider the cost. Some insurance plans cover these drugs, especially if you have a documented obesity diagnosis (BMI ≥ 30 or ≥ 27 with a comorbidity). If coverage is limited, ask about patient assistance programs directly from the drug manufacturers.

Choosing the right prescription weight loss drug boils down to understanding how each one works, matching it to your health profile, and staying vigilant about side effects. Talk openly with your healthcare provider, set realistic goals, and remember that lasting weight loss is a marathon, not a sprint.