Common medication errors with GLP-1 therapies: What patients and providers should know

GLP-1 medications are transforming diabetes and obesity care, and their reach is about to expand dramatically. Medication safety experts at ISMP, an ECRI company, have identified common errors and provided guidance to help patients and clinicians get the most from these breakthrough treatments.

GLP-1 receptor agonists — including semaglutide and tirzepatide — are reshaping how clinicians treat type 2 diabetes and obesity, with clinical outcomes that are drawing significant attention. Experts at the Institute for Safe Medication Practices (ISMP), an ECRI company, are highlighting both the promise of these medications and practical steps patients and providers must take to use them safely.

Emerging evidence suggests GLP-1 medications could reduce all-cause mortality in the U.S. by 6.4% over 20 years. Clinical trials show weight loss ranging from approximately 5% to more than 20% when combined with lifestyle changes — even modest reductions can meaningfully lower blood pressure and cardiovascular risk. A CDC analysis estimated roughly one in four people with a diabetes diagnosis are currently using a GLP-1 medication.

"These medications represent an advancement in care for many patients," said Jana O’Hara, ISMP’s Director of Consulting and Education. "Our goal is to make sure patients and providers have the information they need to use them safely and know how to prevent the common errors we are seeing."

Access is also about to expand significantly. Starting July 1, 2026, CMS will offer eligible Medicare Part D beneficiaries GLP-1 medications for just $50/month through the Medicare GLP-1 Bridge program—making it all the more critical that patients and providers stay on top of safety concerns.

Most Errors Are Preventable -- and Reported Cases Point to Clear Patterns

As use has grown, so has the variety of products on the market — including compounded formulations that have introduced additional complexity. ISMP experts have identified several recurring error types that, while not widespread, carry real consequences when they occur:

• Dosing confusion. When prescriptions are written in milligrams or milliliters, but syringes are marked in units, this can create measurement mismatches. Patients and providers should confirm dosages and units of measurement at every step.
• Dispensing errors. Because GLP-1 doses are adjusted over time, often monthly, confirming the correct dose is essential at pickup from the pharmacy or when it is delivered to -the home.
• Multi-dose pen misuse. Patients should follow provider instructions precisely rather than attempting to estimate doses by counting clicks or splitting doses.
• Reusing single-dose vials. These vials do not contain preservatives and should be discarded after one use. Once punctured, they are not safe to store for later use.
• Counterfeit and substandard products. As out-of-pocket costs rise, some patients turn to compounded products from less regulated sources. Many lack clinical evidence for safety or efficacy and are not approved for human use, including those sold online as "research use only."  When buying medications outside traditional pharmacy channels, watch for warning signs including spelling errors on packaging, unclear or missing labels, or missing instructions.

What Patients Should Do 

• Verify your prescription is correct. Confirm that you have the correct dose and unit of measurement every time you receive your medication.
• Learn proper administration techniques. If the injection process is unclear, ask a physician, nurse practitioner, or pharmacist for a demonstration. Manufacturers also have video resources on their websites that provide this important education.
• Use medications as directed. Follow instructions carefully--do not estimate doses and only use single-dose vials once.
• Check for signs of counterfeit and substandard medications. Raise any concerns about medication authenticity with a clinician.
• Report medication errors to ISMP. Submitting a report to ISMP’s consumer error reporting program helps identify patterns and improve safety across the healthcare system.

What Clinicians Should Do

• Verify prescription accuracy. Ensure the prescribed dose and unit of measurement match the patient’s medication and device. Double-check dosing instructions, especially when transitioning between products or formulations.
• Educate patients on administration. Provide clear demonstrations or instructions for injection technique, including proper use of multi-dose pens and single-dose vials. Encourage questions and clarify any uncertainties during dispensing or follow-up visits.
• Check for counterfeit and substandard medications. Ask patients where they are obtaining their medications. Advise patients to use reputable pharmacies. Inspect packaging and labeling for accuracy, address patient concerns about medication authenticity, and report suspicious products.
• Encourage reporting of errors. Promptly report any medication errors, near misses, or unsafe situations to ISMP or other relevant safety organizations. Use these reports to identify patterns and improve practice safety.
• Stay informed about updates and best practices. Regularly review guidance from ISMP, ECRI, and other trusted sources on GLP-1 therapy safety. Share updated information with colleagues and patients.

For a video with more information and links to resources on GLP-1 safety: https://www.youtube.com/watch?v=RVdhSqzOKdQ

ISMP is the nation's first nonprofit devoted entirely to medication error prevention and safe medication use, and is a part of ECRI, a global organization advancing safe, evidence-based healthcare.