GLP-1 Overdoses and Dosing Errors: Poison Center Data, Tenfold Vial Mistakes, and When to Get Help

Poison centers in the United States are getting more calls about GLP-1 drugs every year. Most of these calls are about dosing mistakes, not deliberate overdoses: a person injects a full dose instead of a starter dose, takes a weekly drug every day, or draws ten times too much from a vial.

Most of these cases are handled without a trip to a hospital or clinic. In national poison center data, the most common problems are nausea and vomiting, and serious outcomes are uncommon. But the drugs stay in the body for days, so a large mistake can mean days of vomiting, dehydration, and sometimes a hospital stay. A small number of published cases describe intensive care, a bowel that stopped moving, or dangerously low blood sugar.

The most error-prone setups are vials, not prefilled pens. Compounded semaglutide and tirzepatide, and unapproved drugs such as retatrutide sold online as "research chemicals," often come as vials that the patient measures with a syringe. That is where milligrams, milliliters, and "units" get mixed up.

Poison centers are staffed by nurses, pharmacists, and doctors trained in toxicology, and they log each call in a national database called the National Poison Data System (NPDS). An "exposure" in that database means someone had contact with a substance and a center was called about it, which is not the same as a confirmed overdose or a confirmed harm, and many mistakes are never reported at all.

Three national studies used NPDS data:

• 2017 to 2022. Researchers at Nationwide Children's Hospital counted 5,713 single-substance GLP-1 exposure cases. About 80% (79.9%) were therapeutic errors, meaning unintentional mistakes in taking or giving a medicine, and just over one in five (22.4%) were seen at a health care facility, and 6.2% had a serious medical outcome, including one death. The rate of cases jumped 80.9% from 2021 to 2022.
• 2012 to 2023. A UT San Antonio team found 10,033 exposures, 6,920 of them after semaglutide was approved for weight loss in 2021 (the study used July 1, 2021 as the dividing line). After that date, semaglutide made up 64.2% of exposures, and its call volume rose an extra 9.9% each quarter. Most cases were unintentional dosing errors with mild stomach symptoms, but the share managed in or referred to a hospital or clinic rose from 23.0% to 33.5%.
• 2017 to 2024. A second Nationwide Children's study counted 13,924 single-substance exposures. The rate per million people rose from 0.97 in 2017 to 18.79 in 2024. Therapeutic errors made up 86.2% of cases, and most exposures (91.7%) had no effect, minor effects, or were not followed up; 8.0% had moderate effects, and 42 had major effects.

The UT San Antonio authors note a practical problem with this data: because poison centers often record the dose as "clicks," "units," or volume, the researchers could not tell exactly how much drug people took, and they could not separate compounded products, whose strength varies, from brand-name pens.

The Washington Poison Center received 543 calls involving GLP-1 drugs from January through September 2026, double the 272 calls it took in the same months of 2025, KIRO 7 reported on November 4, 2026.

Jimmy Leonard, a pharmacist and toxicologist at the center, told KIRO 7 that medication errors are the most common reason for calls. They tend to happen when someone starts a drug, moves up a dose, or shares medicine. A common example is a tenfold overdose: a person meant to start at 0.25 mg and took 2.5 mg instead. He said the biggest concern is a person who cannot keep fluids down.

In a post on the center's website, Leonard wrote that GLP-1 exposures reported to U.S. poison centers grew from about 2,500 in 2022 to 4,700 in 2023 and 8,500 in 2024, with 10,745 through September 2025. The post does not name its data source, and these totals are larger than the peer-reviewed counts above, which include only cases involving a single substance. He also wrote that some patients inject daily for several days instead of once a week, and that people using compounded vials are often confused by doses written in "units," as with insulin.

Brand-name pens such as Wegovy, Ozempic, and Zepbound deliver a preset dose, but vials do not. With a vial, the patient draws liquid into a syringe and has to know three things: the dose in milligrams (mg), the concentration of the vial in milligrams per milliliter (mg/mL), and how the syringe is marked.

Many compounded GLP-1 vials are sold with U-100 insulin syringes, which are marked in "units." On a U-100 syringe, 100 units equals 1 mL, so the units measure the volume of liquid, not the amount of drug it contains. The same 0.25 mg dose can be a different number of units depending on the vial:

• At 2.5 mg/mL, 0.25 mg is 0.1 mL, which is 10 units.
• At 5 mg/mL, 0.25 mg is 0.05 mL, which is 5 units.

A misplaced decimal point, or instructions written for a vial of a different strength, can therefore make the dose ten times too high.

In July 2024 the FDA warned about exactly these errors with compounded semaglutide. In most reports, patients drew five to 20 times the intended dose from multiple-dose vials. In several, patients were told to draw 5 units (0.05 mL) on a U-100 syringe and drew 50 units. Health care providers also made calculation errors: one meant to prescribe 0.25 mg (5 units) and wrote 25 units, a fivefold overdose; another wrote 20 units instead of 2, a tenfold overdose that affected three patients. People reported nausea, vomiting, abdominal pain, fainting, headache, dehydration, pancreatitis, and gallstones, and some needed hospital care.

Published case reports show the same pattern. A regional poison control center described three patients who got compounded semaglutide from compounding pharmacies and an aesthetic spa; two injected tenfold doses, and one received a vial and syringes from a compounding pharmacy with no counseling from a pharmacist. New York toxicologists reported three people who injected 1.7 to 2.4 mg at the start of treatment, including one who took 2 mg instead of 0.1 mg.

Pens are not foolproof. Doctors in Switzerland reported a man on weekly semaglutide 2.4 mg who injected a total of 9.6 mg because of a pen-handling error. For how starting doses and step-ups are meant to work, see our guide to GLP-1 dosing schedules and missed doses.

The usual effects of too much GLP-1 drug are stronger versions of normal side effects: nausea, vomiting, stomach pain, and not being able to eat. In the 2012 to 2023 national data, nausea was reported in 30.7% of exposures after 2021 and vomiting in 28.5%. The Washington Poison Center says tenfold overdoses usually cause severe nausea, vomiting, and food intolerance, and some people need prescription anti-nausea drugs and intravenous (IV) fluids.

These drugs leave the body slowly. The half-life, the time it takes for half of a dose to be cleared, is about one week for semaglutide and about five days for tirzepatide, according to their FDA labels. Both labels say treatment is supportive, meaning doctors treat the symptoms because there is no antidote, and that a period of observation may be needed because of the long half-life. Both labels list the Poison Help line, 1-800-222-1222.

In that poison center's three cases, most symptoms lasted for days. The patient who went to a health care facility improved with an anti-nausea drug and IV fluids. Repeated vomiting can also cause dehydration, and the Zepbound label notes that kidney injury reported with these drugs has mostly occurred in people who became dehydrated from nausea, vomiting, or diarrhea.

Not every overdose causes symptoms. An 80-year-old man with type 2 diabetes and mild memory problems injected 1 mg of semaglutide every day for a week and reported no side effects, with normal kidney, liver, and pancreas tests five weeks later. The man who took 9.6 mg had no nausea at all, but developed a burning skin sensation (dysesthesia) and weakness that went away within seven days.

GLP-1 drugs lower blood sugar mainly when it is high, so on their own they rarely push it too low. The risk rises when they are combined with insulin or sulfonylureas, a class of diabetes pills. The Wegovy label says overdoses of GLP-1 drugs have caused severe nausea, severe vomiting, and severe hypoglycemia (low blood sugar).

Poison center data put numbers on this. At the Rocky Mountain Poison and Drug Safety Center in Denver, hypoglycemia was found in 8 of 237 GLP-1 cases (3.4%) from 2014 to 2023, and the authors said these patients often needed a hospital stay. In the national 2012 to 2023 data, hypoglycemia was recorded in 2.4% of exposures after 2021. Those records often lack a full medication list, so the authors could not rule out insulin or sulfonylureas.

Low blood sugar has also been reported in people taking these drugs for weight loss. A 50-year-old woman who accidentally injected 2 mg of compounded semaglutide as her first dose, ten times the usual starting dose, developed severe swelling of the lips and throat and needed a breathing tube for four days; her hospital stay was also complicated by low blood sugar that required IV dextrose. In the United Kingdom, a 39-year-old man with no major health problems who raised his tirzepatide dose quickly without supervision developed life-threatening hypoglycemia, aspiration pneumonia, and failure of several organs, and needed a long intensive care stay and complex rehabilitation.

The Washington Poison Center advises that anyone being watched at home after an overdose should know the signs of low blood sugar.

Serious outcomes are uncommon in poison center data, but they do occur. In the 2017 to 2024 national study, 42 exposures had major effects and two people died. A 39-year-old woman had a reaction to tirzepatide that involved bowel damage and repeated cardiac arrest; the poison center judged the drug to have contributed. A 79-year-old man who took semaglutide doses too close together had confusion, low blood sugar, and a stopped heart, and the role of the drug was rated unknown.

Case reports add other examples. Doctors in Japan reported a 53-year-old woman with type 2 diabetes and bulimia who injected tirzepatide 7.5 mg, 10 mg, and 15 mg on three days in a row and developed paralytic ileus, a condition in which the bowel stops moving, that took three weeks to resolve. Her doctors linked the long duration to tirzepatide's long half-life.

These reports describe single patients and cannot show how often such outcomes occur. They do show that a large dose can cause more than a few bad days.

The 2017 to 2024 national study looked separately at children aged 6 to 17. They made up only 178 of the 13,924 exposures, but their rate rose from 0.04 per million in 2017 to 1.97 per million in 2024, with most of the increase after 2021.

Compared with adults, children in this age group were more likely to be admitted to a hospital and more likely to vomit, and teens aged 12 to 17 were more likely to have a more serious outcome. One in three exposures among children (32.6%) was coded as intentional misuse, which in this database means using a drug incorrectly on purpose, for reasons other than getting high. The study did not include children under 6. For background on the drugs in this age group, see our article on teens and GLP-1 drugs.

Unapproved drugs bought online carry all of the vial problems plus uncertainty about what is in the vial. These products are often sold as a dry powder that the buyer mixes with liquid at home, a step a pharmacist would normally do in a clean setting.

KIRO 7 described a woman who lost insurance coverage for Zepbound and bought retatrutide, an experimental drug from Eli Lilly that has not been approved, from a website that labeled it "not for human or veterinary use." She paid about $200, got vials of powder with no instructions, mixed them using directions she found online, and later realized she had probably doubled her dose. She had heavy sweating, nausea, an upset stomach, and a racing heart. Leonard told KIRO 7 that buyers of these products may not know what they are getting and that contaminated products could cause serious harm.

The Washington Poison Center says retatrutide callers have reported vomiting and being unable to keep down food or liquids for one to three days. The FDA says it has warned companies selling semaglutide, tirzepatide, retatrutide, and similar drugs falsely labeled "for research purposes" or "not for human consumption" and sold directly to consumers with dosing instructions. For lab tests of these products, see our article on buying retatrutide or zenagamtide online, and for what the label means legally, see why "research use only" peptides are treated as drugs. People who try very small "microdoses" from vials face the same measuring problem; see microdosing Ozempic.

Call Poison Help at 1-800-222-1222. The line connects you to your local poison center, and America's Poison Centers describes it as free, confidential, expert medical advice, staffed by nurses, pharmacists, and doctors at all hours, every day of the year. The FDA labels for Wegovy and Zepbound both give this number for overdoses. Have the vial or pen, the dose you meant to take, and the amount you think you took ready.

Know the warning signs. Get medical care if you:

• cannot keep fluids down, the concern Leonard called the biggest one;
• have severe stomach pain that does not go away, especially if it spreads to your back, which the Zepbound label lists as a sign of pancreatitis;
• have signs of low blood sugar, which the Zepbound medication guide lists as including shakiness, sweating, confusion, dizziness, and a fast heartbeat, especially if you also take insulin or a sulfonylurea;
• have swelling of the face, lips, tongue, or throat, trouble breathing, or fainting, which the same guide says need medical help right away.

Expect it to last. Because these drugs stay in the body for days, symptoms can continue for several days after the injection, so ask your prescriber before taking your next scheduled dose.

Prevent the next one. If you use a vial:

• Write down your dose in milligrams, the vial's concentration in mg/mL, and the matching number of units or milliliters, and check that the math agrees.
• Ask the pharmacy to confirm the units for your syringe each time the concentration or the dose changes. The FDA told compounders to supply the right syringe and to counsel patients.
• Do not reuse instructions from a different vial, pharmacy, or friend.
• Report errors and side effects to the FDA's MedWatch program; the FDA says many compounded-drug problems go unreported.

For help choosing a pharmacy, see how to evaluate a compounding pharmacy. For normal side effects at the start of treatment, see how long GLP-1 nausea lasts.