As more people take the injectable weight-loss medication Wegovy, they should be aware of concerning reports of overdoses. That drug, more generally called semaglutide, can have unpleasant gastrointestinal side effects at prescribed doses. But if people take too much semaglutide, the adverse effects can be severe and even require hospitalization. The Food and Drug Administration recently alerted health care providers, pharmacies and the public about the dangers of overdoses from semaglutide, which is also prescribed under the name Ozempic to treat diabetes. Scientific American spoke to experts about how people using semaglutide and similar weight-loss medications can stay safe.
How can people overdose on semaglutide?
These incidents often happen when people are required to portion their own doses of the medication. Novo Nordisk, the company that produces semaglutide, provides injectable forms of the medication in disposable injector pens with preportioned doses. But many people are reportedly receiving such medication through a different (and usually cheaper) source: compounding pharmacies. These facilities are allowed to replicate and dispense patented medications that are in shortage.* Such drugs include semaglutide, which has been listed as “in shortage” by the FDA since 2022.
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Compounding pharmacies typically dispense these drugs in vials with accompanying syringes, leaving the patient to draw up their own dose as prescribed by their doctor. "You have to know conversions, and you have to know how much to draw up,” says Janice Jin Hwang, an endocrinologist at University of North Carolina at Chapel Hill.
These conversions can be complicated. Doses are sometimes prescribed in milligrams but dispensed in syringes that are marked in milliliters—and these may be ambiguously referred to as “units.” Additionally, the syringes people receive can be far larger than the intended dose, potentially leading to a much higher one. According to the FDA, some individuals injected anywhere from five to 20 times the prescribed dose.
These wonky conversions have even confused doctors. The FDA overdose alert cited two cases in which doctors prescribed patients an incorrect dose. (Doses can vary among people and throughout the course of treatment. Regimens should be determined at the discretion of a health care provider.)
"You really have to know exactly what you’re doing. Otherwise it's really, really easy to make mistakes," Hwang says.
What happens when people take too much of these medications?
Taking too much semaglutide can cause severe gastrointestinal symptoms, such as nausea, vomiting and abdominal pain. People who have experienced dosing errors have also reported fainting, headaches, migraines, dehydration, gallstones and acute pancreatitis, or inflammation of the pancreas, which can be life-threatening. (These drugs are known to carry a risk of pancreatitis and gallbladder disease.) Many of these people sought out medical care or were hospitalized.
The injections are formulated to stay in a person’s system for up to a week but can persist even longer. This means that the symptoms from an overdose may need to be monitored and treated for an extended period of time.
How much is too much?
Doses vary depending on the individual. Doctors typically start patients on a low dose and adjust, or “titrate,” the amount upward every four weeks until they find a dosage that’s tolerable and maintains the desired weight-loss effects, Hwang says. For adults, Wegovy’s dose starts at 0.25 milligram per week and can progress up to 2.4 milligrams.
How can people make sure they’re injecting the appropriate amount?
Pharmacists and the prescribing health care provider should help with any questions about dosing. “For someone who’s new to drawing up medications in a syringe, [you] just have to be taught how to do it correctly,” Hwang says. If you are picking up your prescription from a brick-and-mortar pharmacy, you can ask your pharmacist to demonstrate how to draw up the correct dosage.
In-person demonstrations aren't an option for people who receive medication in the mail, however. Many telehealth providers that prescribe injectable weight-loss medications partner with compounding pharmacies that send them to people’s doorstep. This may leave some people with only written instructions for drawing up doses and injecting themselves with the drug. “I’m actually really worried about that,” Hwang says. In one overdose case reported to the FDA, a person who received compounded semaglutide through a telehealth company found it “difficult to obtain clarity” about the dosing instructions from the provider and instead searched online for help. They accidentally took five times the correct dose.
“It’s really important with these types of drugs that pharmacists and providers make sure to provide their patients with adequate counseling, education, and materials and be available when patients have questions,” says Tenille Davis, a pharmacist and chief advocacy officer of the Alliance for Pharmacy Compounding, which represents the interests of compounding pharmacies in the U.S. Even if people receive the medication through the mail, there should be a pharmacy name and phone number on the label. “Just like a prescription filled from a mail-order pharmacy for [a] cholesterol medicine, there’s a pharmacist on the other end of that,” she says. If a relevant doctor isn’t available, Tenille says to reach out to the pharmacist for medical advice—not Facebook, Reddit or other online communities.
Hwang agrees. “I wouldn't trust the Internet with [dosing questions] because it depends on the syringe that you’re using, and it depends on the concentration of the medication.”
Beware the scams
Alongside legitimate telehealth providers that partner with compounding pharmacies, there are also a growing number of illegal operations and scam websites claiming to sell semaglutide. The National Association of Boards of Pharmacy (NABP) have identified more than 40,000 of these sites. Some of them can even look legitimate and may promise name-brand weight-loss drugs at a temptingly steep discount and without a prescription. In a recent article in the Journal of the American Medical Association, researchers describe what they found after purchasing products from some of these sites.
“These are the bottom-of-the-barrel type of sellers,” says Timothy Mackey, a co-author of the study, who researches counterfeit drug markets at the University of California, San Diego. Half of the research team’s orders were never fulfilled; they were so-called nondelivery scams. And the vials that they did receive were contaminated or impure or contained more semaglutide than disclosed.
“That may mean that [these drugs] weren’t intended for the human market,” Mackey says. The drug might have instead been prepared for research use in a lab. They may not be “up to the authorized standard that you would expect to receive if you bought it from a legitimate source.”
You can verify websites and online retailers on NABP’s search tool of accredited pharmacies. You can also check whether a pharmacy is legitimate and licensed in your state.
*Editor’s Note (8/20/24): This sentence was edited after posting to better clarify the description of compounding pharmacies.