Prescription vs. Over-the-Counter Diet Pills: What's changed and what still matters

Since 2006 the number of FDA-approved prescription medications for weight management has increased. Prescription drugs vary in mechanism, indication, and safety; some are for short-term use and others for long-term therapy under clinician supervision. Over-the-counter diet pills and supplements are not FDA-approved as drugs, may have inconsistent quality, and often lack good evidence. For durable results, combine medical options with sustained diet and activity changes and discuss risks and benefits with a clinician.

Many people consider pills to help with weight loss. Since 2006, the landscape of medically approved weight-loss medications has changed: there are now several FDA-approved prescription drugs for chronic weight management, but over-the-counter supplements remain largely unregulated.

How prescription weight-loss medications are used

Doctors prescribe medications for people with obesity or for those with overweight who also have weight-related health problems. Prescription drugs work in different ways: some suppress appetite, others slow fat absorption, and newer agents act on hormones that regulate hunger and blood sugar.

Currently prescribed options include older short-term stimulants (like phentermine) and several drugs approved for longer-term weight management: orlistat (prescription Xenical and OTC Alli as a lower-dose option), phentermine-topiramate (Qsymia), naltrexone-bupropion (Contrave), GLP-1 receptor agonists such as liraglutide (Saxenda) and semaglutide (Wegovy), and tirzepatide (Zepbound). These medicines have specific indications, dosing rules, and safety profiles. Some are intended for short-term use; others are approved for ongoing therapy when supervised by a clinician.

All prescription medications carry potential side effects and contraindications. For example, stimulants can raise heart rate and blood pressure, and some newer agents commonly cause gastrointestinal symptoms. Pregnant people and those with certain medical histories should not take specific drugs. A clinician evaluates benefits, risks, cost, and interactions before prescribing.

Over-the-counter pills and supplements

A large market of OTC diet pills and herbal supplements promises fast results. Unlike prescription drugs, most of these products are not evaluated or approved by the FDA for safety or effectiveness. In the U.S., dietary supplements are regulated under the Dietary Supplement Health and Education Act (DSHEA); manufacturers are responsible for product safety and labeling, and the FDA intervenes only after problems are reported.

That means ingredient quality, purity, and potency can vary. Some products have been found to contain undeclared prescription drugs or stimulants. Expect limited evidence for effectiveness and a higher risk of misleading claims.

Realistic expectations and long-term approach

Medications can help people lose weight and improve metabolic health, but they are not a cure on their own. Best outcomes combine medication (when appropriate) with sustained changes in diet, activity, and behavior. Many people regain weight after stopping a medication if they do not maintain lifestyle changes.

Talk with your clinician

If you are considering weight-loss medication or supplements, discuss goals, medical history, and other treatments with a clinician. Ask about evidence for effectiveness, side effects, duration of treatment, monitoring, and cost. If you choose an OTC product, look for third-party testing and be cautious of any product that promises rapid, effortless, or permanent weight loss.