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After years of fad diets and even gastric bypass surgery, Robin Demoy turned to the weight-loss drug Wegovy. The once-a-week injection helped the New Hampshire travel agent shed more than 60 pounds.

But when she got up one morning several weeks ago, Demoy was so dizzy it felt like she had motion sickness. Her legs turned weak, and she was nauseous. She vomited and had little desire to eat for weeks.

The 52-year-old did not want to stop taking Wegovy, part of a wave of medications that have exploded in popularity, sparking a cultural phenomenon, sporadic shortages and a potential gold rush for pharmaceutical firms. For Demoy, the benefits of weight loss exceed the discomfort.

“Dealing with these side effects is new territory for everybody,” Demoy said. “Even the doctors.”

As more people turn to blockbuster diabetes and obesity drugs such as Wegovy, Ozempic and Mounjaro, some are grappling with an unwelcome trade-off: how to balance uncomfortable, sometimes painful, side effects with the benefits of reduced food cravings and the loss of substantial weight.

Most people who take the drugs don’t experience serious side effects, and even minor ones — nausea, diarrhea, vomiting — mostly can be controlled with a careful diet and medical supervision. But patients say some unwelcome and scary effects — including heart palpitations — surprised them, forcing them off the medication.

In the case of Demoy, who lives in Moultonborough, N.H., she tried staving off nausea by drinking electrolytes to stay hydrated and eating more protein. Finally, her doctor lowered her weekly dose — and her symptoms eased.

Diabetes and weight-loss drugs in the United States have a troubled history, but the new generation, which includes Ozempic and Wegovy, offers greater effectiveness and fewer safety problems, studies show. The drugs raise the tantalizing potential of helping millions of people lose weight, easing the nation’s epidemics of diabetes and obesity. More than 14 percent of adults in the United States have diabetes and almost 42 percent have obesity, according to the Centers for Disease Control and Prevention.

Americans are increasingly aware of the drugs’ promises. According to a KFF health tracking poll released Friday, nearly half of adults indicated they would “generally be interested” in taking a “safe and effective” weight-loss drug, and nearly 7 in 10 adults had heard at least “a little” about the medications.

Ozempic is approved for Type 2 diabetes but is often taken off-label for weight loss. Wegovy, which has the same active ingredient, called semaglutide, is cleared for obesity and reduces body weight by an average of 15 percent, according to a key study.

An Eli Lilly diabetes drug called tirzepatide helped people reduce body weight by up to 26 percent, on average, in late-stage studies, the company said recently. The medication is already approved for diabetes under the brand name Mounjaro and is expected to be cleared for obesity by the end of the year.

All three drugs mimic a naturally produced hormone — called glucagon-like peptide-1 — that increases insulin production, suppresses appetite and slows the emptying of the stomach, creating a full feeling even when patients eat less. Mounjaro also mimics a second, closely related hormone called GIP, which also stimulates insulin production. Researchers say having two targets produces a more powerful effect.

Drugmakers are developing versions of the drugs that can be taken as pills and that target additional hormones. Lilly recently bought a company called Versanis, whose drug, bimagrumab, targets fat cells directly.

Novo Nordisk, which makes Ozempic and Wegovy, said gastrointestinal side effects are mild to moderate and well-recognized. “Semaglutide has been extensively examined in robust clinical development programs, large real world evidence studies and has cumulatively over 9.5 million patient years of exposure,” a statement from the pharmaceutical company said.

Lilly said side effects from tirzepatide “were mostly mild to moderate, usually occurred during the dose-escalation period, and subsided once treatment discontinued.”

The drugs’ list prices are about $1,000 to $1,300 a month. Private insurance generally covers diabetes drugs but often does not pay for medicines used for weight loss. A recently published analysis of pharmacy and medical claims data showed nearly 70 percent of patients who had taken Wegovy and another weight-loss drug, Saxenda, were no longer using the medications; the analysis did not address patients’ reasons for stopping the medications.

Obesity experts say patients’ experiences with side effects vary.

“Some people get very sick, and others have no side effects at all,” said Robert F. Kushner, a professor of medicine and medical education at Northwestern University who conducted pivotal trials involving semaglutide, which were paid for by Novo Nordisk. Kushner also has worked with other health-care companies.

On Facebook support groups devoted to the weight-loss drugs, patients post inspirational accounts of their journeys, before-and-after photos and their latest healthy recipes. The pages are also hubs for complaints and home remedies: peppermint oil for constipation, ginger chews for nausea, pickle juice for dehydration.

In a Mayo Clinic study presented in May, half of 305 patients using semaglutide drugs for weight loss over one year suffered side effects, the most common being nausea and diarrhea. Another study published in Nature noted that 82 percent of participants taking a semaglutide drug reported adverse effects, generally mild to moderate gastrointestinal problems. Just nine participants, less than 6 percent of the group, quit because of the side effects, the study reports.

Courtney Blair, 40, was not able to handle the stomach pains caused by Ozempic. She started on the lowest dose, 0.25 milligrams, in February and took Pepto-Bismol or Pepcid tablets for occasional nausea. By mid-April, her doctor had upped her dose to 0.5 milligrams.

“My body violently rejected it,” said Blair, a business systems analyst in Vancouver, Canada, who does not have diabetes and was taking Ozempic to lose weight.

Stomach pain hit Blair so hard that she could see her skin rippling from the intense cramps. “I was projectile vomiting and other gross things,” she said. “It was so painful that I thought I was going to have to call 911.”

Barely able to get out of bed, Blair missed three days of work. She took a break from Ozempic for one week but had the same reaction after restarting it.

Her doctor switched her to Saxenda, a daily-injection drug from the class known as liraglutide approved by the Food and Drug Administration for managing obesity. The drug causes only occasional nausea and slight headaches, she said. But Blair says Ozempic — which helped her lose 17 pounds, down to 220 — was more effective in curbing obsessive thoughts about food.

“It really does encourage you to make better food choices,” said Blair, who is now seeing an obesity specialist.

Obesity experts say many side effects can be reduced by a cautious approach to two important areas: dosing and diet. To avoid nausea and vomiting, high-fat foods — which take longer to digest — or large amounts of food should be avoided, particularly right after the injections.

“Have a modest dinner, watch out for fatty foods and oils for a day or two, and stop eating as soon as you feel full,” Kushner said. “Don’t take a shot on Friday night when you are planning on partying over the weekend.”

Terry Simpson, a weight-loss surgeon in Ventura, Calif., said some patients who get their drugs from online providers are not getting adequate advice on what to eat when taking the drugs.

“When you ask them what they were told, they say, ‘I was just told to eat better,’ without any specifics,” Simpson said.

In some cases, providers who lack experience with the drugs are being too aggressive about ramping up dosages, experts say. Wegovy doses should be increased gradually, taking five months to go from 0.25 to 2.4 milligrams. If the treatment causes nausea, the dose should be kept the same — or decreased — until the patient adjusts.

“We should titrate the drug as tolerated by the patient,” said Ania M. Jastreboff, associate professor of medicine and pediatrics at Yale School of Medicine.

Jastreboff said her motto is: “Start low, go slow.” Jastreboff led a key trial for Mounjaro, which was sponsored by Lilly, and she also advises other pharmaceutical firms.

Still, the recommended dosing schedules don’t always prevent side effects.

Tia Koch, 40, a schoolteacher in Reading, Pa., was on the lowest dose of Wegovy before increasing it after a month. The next day, nausea hit her in waves. At school, co-workers gave her ginger ale and a motion-sickness pill, but she threw up and retreated to a classroom closet to agonize in pain. That night, the symptoms were so bad that Koch checked into a hospital, where she had nausea and an elevated heart rate for several days.

The nausea disappeared. But days after leaving the hospital, Koch’s chest and throat still felt sore from the vomiting. She has stopped taking Wegovy and plans to cut food portions in half.

“We want instant results, and this seemed like a miracle drug,” Koch said.

This month, a Louisiana woman with a similar story sued Novo Nordisk and Eli Lilly, alleging the companies have downplayed severe gastrointestinal issues. The patient asserted that she was prescribed Ozempic, then Mounjaro, over the course of a year and a half, and wound up hospitalized because of stomach pains and vomiting so violent she lost teeth. The woman’s law firm, Morgan and Morgan, says it has been retained by more than 500 clients in 45 states with similar stories.

Another undesirable result of the drugs is potential loss of lean muscle along with fat, which can occur when there is rapid weight loss, regardless of the method used, doctors said. Lean muscle is important for keeping bones strong, protecting against diabetes and reducing the risk of falls, a concern especially for older people. Loss of lean muscle can happen to anyone who loses weight quickly, regardless of the method, doctors said.

Sahar Takkouche, assistant professor in the division of endocrinology, metabolism and diabetes at Vanderbilt University Medical Center, said patients can take steps to minimize the loss of lean muscle, including eating enough protein and exercising. Strength training is especially important.

There are other things to consider when taking the medications. The drugs should be stopped before elective surgery, the American Society of Anesthesiologists said in June.

“We’ve received anecdotal reports that the delay in stomach emptying could be associated with an increased risk of regurgitation and aspiration of food into the airways and lungs during general anesthesia and deep sedation,” the organization said in a statement.

Recently, the European Medicines Agency, which regulates pharmaceutical products, said it had begun investigating the class of drugs that includes Ozempic and Wegovy following three reports from Iceland’s health regulator of patients thinking about self-harm or suicide. The review has been expanded to evaluate 150 reports of possible cases of self-injury or suicidal thoughts, the European agency said in a statement.

The FDA said it generally “does not comment on third-party research or individual reports” but may evaluate them.

Demoy, the travel agent, said she plans to stay on Wegovy despite her bouts of lethargy and nausea. She originally had been taking Saxenda, but she said it stopped working as effectively — the obsessive thoughts about food crept back.

The side effects started only after she switched to Wegovy, initially at a weekly dose of 2.4 milligrams. Still, Demoy is pleased with the greater health benefits. Her cholesterol and sodium levels have dropped. Her blood pressure has come down enough that her doctor wants to wean her off two additional medications, she said.

“I’m staying on this the rest of my life,” Demoy said. “I’m doing this because it’s right for my health.”