Weight-loss medications may help. They also may hurt. Here's what you need to know.

Could 93 million Americans benefit from taking weight-loss drugs? That's what a new study predicts. The population analysis of 3,999 adults estimates that a 2.4 milligram dose of Wegovy could be a good fit for those with obesity or overweight.

Weight-loss medications, including Wegovy (which was approved by the Food and Drug Administration (FDA) to treat adults with obesity in 2021) and similar medications like Ozempic (semaglutide) and Mounjaro (tirzepatide), have been tied to not only weight loss but also to a lowered risk of heart attack and stroke, making it seem like these are wonder drugs — for a while, at least. But there have been reports of certain medications leading to serious complications for users, including stomach paralysis and cyclic vomiting. Many of the studies that show large advances in weight loss were conducted by the drug manufacturers, making the results less reliable than studies led by independent parties. There are also allegations that doctors prescribe these medications for people who do not have overweight or obesity.

With all of these issues, it's understandable to be confused about weight-loss medications. Are they helpful, harmful or somewhere in-between? And who should be taking them? Here's what the research and doctors who work with patients who have obesity have to say.

What does the research say about weight-loss medications?

A lot of data indicates that these medications — which typically fall into a class known as GLP-1 receptor agonists — can lead to significant weight loss. But, again, such studies are largely conducted by the companies that make the drugs.

Ozempic, which has gotten a lot of attention for weight loss but has technically been FDA-approved only to treat type 2 diabetes, helped people in one study lose up to 14 pounds, according to the drug's official website. Novo Nordisk, which makes Ozempic, also notes that research found that people on Ozempic lost an average of 8 pounds on 0.5 milligrams of the medication and 10 pounds on 1 milligram of the medication (compared to 3 pounds on a placebo). Another study found that people lost 12 pounds on 1 milligram of Ozempic and 14 pounds on 2 milligrams, according to the company.

Fellow semaglutide medication Mounjaro led to weight loss of 15.7% over 72 weeks in people who took 15 milligrams of the drug, Eli Lilly, which makes the medication, announced in April. Study participants who took 10 milligrams of Mounjaro lost up to 13.4% of their body weight during that time, while people in the placebo group only lost an average of 3.3%, the company said.

Novo Nordisk, the company that makes Wegovy, said in a press release issued in early August that a recent clinical trial found that Wegovy lowered the risk of stroke, heart attack and cardiovascular deaths by 20% compared to people who used a placebo. The study, which hasn’t been peer-reviewed or published yet, was a double-blind, placebo-controlled trial of 17,604 adults ages 45 years or older who have overweight or obesity and had established cardiovascular disease, according to Novo Nordisk.

Patients were either given shots once a week of Wegovy or a placebo, along with the standard of care to prevent major cardiovascular events over five years. The researchers discovered that people who took Wegovy had a “statistically significant and superior reduction” in the risk of major cardiovascular events compared to those who took the placebo, Novo Nordisk says.

There are more medications in the pipeline, too. Phase 2 clinical trial results for Eli Lily’s experimental drug retatrutide show that the medication may be even more effective than Ozempic and others. The study, which was published in the New England Journal of Medicine, followed 338 adults with obesity who took retatrutide injections or a placebo for 48 weeks. At the end of the study, the researchers found that people in the retatrutide group who took 12 milligrams lost around 24% of their body weight. (People in the placebo group lost 2% of their body weight.)

Benefits of weight-loss medications

For all of the chatter, experts stress that these medications aren't for everyone. "Not everyone needs medications to treat their obesity," Dr. Fatima Cody Stanford, an instructor of medicine and pediatrics at Harvard Medical School and obesity medicine physician at Massachusetts General Hospital, tells Yahoo Life. "Some patients may need behavioral and lifestyle modifications, while others may need metabolic and bariatric surgery. Many patients may need a combination of lifestyle, behavior, medication and surgery."

The right treatment for a person "should be tailored to each individual person based upon a variety of factors, which include cardiovascular related conditions, obesity, related diseases, family, history, genetics and a host of others," Stanford says.

But those who qualify for these medications can see significant results, Dr. Dina Peralta-Reich, director of New York Weight Wellness Medicine, tells Yahoo Life. "They change lives," she says. "They are a fabulous group of medications when utilized correctly — but you need to be the right candidate."

Every medication is slightly different, but Wegovy, for example, is intended to be used by adults and children ages 12 and up who have obesity (defined by a BMI of 30 or higher for adults and being in the 95th percentile or greater for kids).

"These medications come with a significant benefit for those [who qualify] with minimal to no side effects," Stanford says. "They achieve an average of 15% total body weight loss, which is beneficial for weight regulation. This class of medications has been shown to reduce major adverse coronary events in patients with and without diabetes."

Nathan D. Wong, a professor, researcher and director of the Heart Disease Prevention Program at University of California, Irvine, tells Yahoo Life that the potential heart benefits shouldn't be discounted. "Semaglutide, in particular, as well as other GLP-1 receptor agonists can improve not only weight, but also other cardiovascular risk factors," he says. "They are much more than just about weight loss and patients with overweight or obesity need to know they are at increased risk of cardiovascular diseases such as heart attacks, strokes, peripheral arterial disease and heart failure. The cardiovascular risk-reducing effects of these therapies can beneficially impact their future risk of cardiovascular disease."

Drawbacks of weight-loss medications

These medications come with a risk of certain side effects. While they vary by medication, they generally include nausea, vomiting, diarrhea, heartburn and abdominal pain, Christina Inteso, a clinical pharmacist at Corewell Health, tells Yahoo Life.

There have been reports of stomach paralysis — where the stomach empties at an abnormally slow rate — and cyclic vomiting — sudden attacks of severe, repeat vomiting — with some of these drugs.

"It will slow down your gastrointestinal tract and could cause vomiting, especially if fatty or greasy foods are consumed, but stomach paralysis and cyclical vomiting were not found in other clinical trials that got the medication FDA-approved and is pretty rare in clinical practice," Inteso says.

Peralta-Reich also says that cyclic vomiting and stomach paralysis are rare. Stanford agrees. "At least 90 to 95% of the patients that I have placed on semaglutide have gotten great benefit with weight management and cardiometabolic health benefits," she says. "For those with significant side effects or minimal weight response, I discontinue the agent."

Those may not be the only serious side effects prospective users should keep in mind: Health authorities in the United Kingdom are also currently investigating a link between Ozempic and Wegovy and suicide after some patients who took the drugs said they had thoughts of suicide or self-harm. The U.K.'s Medicines and Healthcare products Regulatory Agency said that it received reports of five adverse reactions in people who used semaglutide that were linked with "suicidal and self-injurious behavior," according to Reuters. Clinical trials have also not established this link.

Who are these medications right for?

As of now, Wegovy is the only semaglutide medication approved in the U.S. for weight loss. Again, it requires that patients must be at least 12 years old and have obesity.

The medications aren't designed to help people just lose a few pounds, Jamie Alan, associate professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life, and it's difficult to know for sure how they'll affect people who are use them off-label. "Please work with a reputable physician when taking these medications," she says.

If you're interested in taking a weight-loss medication and think you're a good candidate, Inteso recommends talking to your doctor about your options. "There’s a lot of information in the media, online, and by word of mouth about semaglutide right now. It’s a very hot topic and with that comes conflicting news and personal anecdotes," she says. "It's important for people to know that it is an effective medication for many people but might not be the best choice for everyone."