Weight Loss Drugs and the Importance of FDA Approval

New weight loss drugs offer hope to millions struggling to shed excess pounds. However, before any drug can be marketed for weight loss—or any other use—it must go through a rigorous approval process with the U.S. Food and Drug Administration (FDA). FDA approval is critical to ensuring these drugs are safe and effective for people to use.

The FDA approval process typically takes years and involves multiple phases of testing. Drugs are tested on animals early to determine toxicity and safety risks. If results are positive, the drug moves on to human clinical trials, where it is tested on volunteers to study how it works in the body and its effects on health and weight loss. These trials also help determine proper dosage ranges and identify potential side effects. 

Phentermine is one of the earliest FDA-approved weight loss drugs. First approved in 1959, phentermine acts as an appetite suppressant and stimulant. Early clinical trials showed average phentermine results of 5 percent of body weight reduction. The FDA approved phentermine with certain restrictions around duration of use and patient criteria based on the initial research. Over decades, further studies have affirmed phentermine’s safety and efficacy when used short term, which is why it is still FDA-approved and prescribed today. 

Recently, drugs like Ozempic (semaglutide) and Wegovy (liraglutide) have been approved by FDA. Originally diabetes medications, Ozempic and Wegovy, were also shown to lead to weight loss. In clinical trials, people using Ozempic lost on average 6 to 8 percent of their body weight, while those on Wegovy lost even more—around 12 percent. Based on these trials, the FDA approved higher doses of Ozempic and Wegovy specifically for chronic weight management.  

The comprehensive FDA approval process for weight loss drugs is important because it helps ensure safety, efficacy, and proper usage guidelines. Without approval, drugs may lack critical safeguards to protect public health. The approval also allows for coverage under health insurance, making treatment more affordable and accessible. 

However, FDA approval alone does not guarantee effectiveness or safety. Rare side effects are still possible, and drugs do not work for everyone. Lifestyle interventions like diet and exercise continue to be the foundation of successful weight loss, with or without medication. FDA-approved drugs may help some people trying to make health changes.

New weight loss drugs are exciting tools, but consumers must make informed choices with guidance from medical professionals. FDA approval gives reasonable assurance of safety and effectiveness, allowing people to move forward confidently. But each person’s experience can differ based on some personal factors. By starting slowly, maintaining realistic expectations, making lifestyle adjustments and monitoring side effects and health changes with the help of your doctor, the benefits of weight loss medication may be achieved.


Weight Loss Drug Side Effects

Some common side effects of prescription weight loss drugs include:

Nausea and vomiting: Nausea is one of the most frequent side effects, especially when starting a weight loss medication. Anti-nausea drugs can help relieve symptoms until your body adjusts. Vomiting can typically be avoided by starting with a low dose and gradually increasing it under medical guidance.

Diarrhea and constipation: Changes in bowel movements are common, ranging from diarrhea to constipation and sometimes alternating between the two. Staying hydrated, eating a high-fiber diet, and using probiotics can help reduce problems. Your doctor may recommend over-the-counter medications if symptoms are persistent.

Dry mouth: Weight loss drugs can reduce saliva flow, leading to dry mouth. Sipping water, chewing sugar-free gum, and avoiding alcohol/caffeine can offer relief. Prescription medication may be needed in some cases.

Fatigue and dizziness: Some people feel tired, drained or lightheaded when starting a weight loss drug. Side effects are often temporary but can be a sign your body is adjusting to the medication or that the dosage needs to be modified. Discuss any ongoing fatigue or dizziness with your doctor. 

Insomnia and restlessness: Certain weight loss drugs may disrupt sleep or cause feelings of restlessness due to their stimulating effects. Taking medication earlier in the day, reducing dosage or switching to a different drug may help. Sleep hygiene practices can also promote better sleep.

Headache: Headaches are a possible side effect, especially during initial use or with dosage increases. Mild headaches typically subside over time, but severe or persistent headaches should be discussed with your doctor as the medication or dosage may need adjustment. 


Fast heart rate: Weight loss drugs that act as stimulants may temporarily raise your heart rate or blood pressure. Your doctor will monitor your vital signs and may lower or switch medications if there are ongoing concerns. Staying hydrated and limiting stimulants from other sources can also help.

The risk of side effects varies based on the specific medication and individual. Starting with a low dose and gradually increasing under guidance from your doctor can help minimize side effects. Be sure to report any severe or concerning side effects right away. 


In summary, FDA approval of weight loss drugs helps provide guidelines for appropriate usage based on scientific evidence from clinical trials. The approval also allows for insurance coverage, making treatment possible for more people. While not a guarantee of effectiveness for each individual, FDA approval gives reasonable confidence that benefits will likely outweigh risks when drugs are used properly under medical supervision. With lifestyle changes also in place, weight loss medication may be an option to discuss with your doctor.