Veggie Blog

Weight loss tablets and safety

What side effects can weight loss tablets cause?

It depends on the product. Even carefully tested prescription medicines can cause nausea, diarrhea or constipation, headache and other mild problems, and the National Institute of Diabetes and Digestive and Kidney Diseases says most side effects are mild and often improve with time, while serious ones are rare. Stimulant-type ingredients found in many over-the-counter products, such as caffeine, are another story. They can raise your heart rate and blood pressure, cause jitters and make it hard to sleep, and in some people they have been linked to chest pain, a racing heart and even heart attack or stroke.

Taking more than the recommended dose is dangerous. Overdoses of stimulant diet products can cause tremors, confusion, hallucinations, seizures and heart rhythm problems, and they need emergency care. If you have taken a product for a while and want to stop, some people report tiredness, low mood, irritability and trouble sleeping. If you are taking a prescription medicine, ask your doctor before you stop.

Are over-the-counter products held to the same standard?

No. In the United States, dietary supplements, including weight loss supplements, do not need FDA approval before they are sold. The manufacturers are responsible for their safety and label claims. The National Institutes of Health Office of Dietary Supplements points out that weight loss products sold as supplements are sometimes tainted with hidden prescription drugs. Of the dietary supplements that were subject to the most serious FDA recalls between 2004 and 2012, 27% were weight loss products. Ephedra, once a common ingredient, was banned from US supplements in 2004 because of safety concerns. The same office concludes that the evidence for supplements helping with weight loss is inconclusive and unconvincing.

Who should be extra careful?

Talk to a doctor before using any weight loss product if you have heart disease, high blood pressure, thyroid, kidney or liver problems, diabetes or a history of seizures or stroke. The same applies if you are pregnant or breast-feeding, under 18, or older, and if you take other medicines, including cold remedies, antidepressants and herbal products, because they can interact. Do not combine weight loss products with each other unless a doctor has prescribed it.

What should you ask your doctor or pharmacist?

Before you start, it helps to ask a few questions. Is this product approved by the FDA for weight management? What are the likely side effects, and which ones mean I should stop? Does it interact with my other medicines? How long should I take it, and what happens when I stop? What should we do if I am not losing weight after 12 weeks? Buy only from a pharmacy or supplier that your doctor or pharmacist trusts, and keep the original packaging so that you can follow the instructions.

Does a tablet work without diet and exercise?

No product does the work for you. Clinical tests show that weight loss tablets only work when they are combined with a lower-calorie diet and an exercise plan. Check with your doctor before starting to exercise, and aim for a mix of cardio and strength training. Adults need at least 150 minutes of moderate activity a week plus two days of muscle-strengthening, according to the CDC. Keep the plan realistic and steady, as we explain in our post on natural weight loss through eating right and keeping moving. For safe-use tips and who should avoid them, see our guide to what to know about diet pills.

To see what doctors can prescribe, and who qualifies, read our post on tablets to help with weight loss. For the ingredients in over-the-counter pills, see what is in a weight loss diet pill.