GLP-1 FAERS Adverse Events: Safety Signals Explained

You’ve seen news stories about adverse events tied to GLP-1 medications. You may have read about FDA investigations or social media posts from people reporting problems. You want to know if those reports are real and whether they change your risk calculation.

This page exists to translate FDA data for you. It explains what FAERS is, how to read it without panicking or ignoring real signals, and what the major FDA safety reviews have actually found. The goal is to give you the facts so you can make an informed decision with your provider.

What FAERS Is and How to Read It

The FDA Adverse Event Reporting System, or FAERS, is a database of voluntary adverse event reports.^[2] Patients, providers, and drug manufacturers can submit reports when someone experiences a side effect or health problem while using a medication.

That’s it. A report in FAERS means someone reported an event. It does not mean the drug caused the event.

The Critical Distinction: Reporting vs. Causation

This is the foundation of understanding FAERS data. A high number of FAERS reports for a drug does not tell you how often an event happens in the population using that drug. It tells you how frequently someone reported that event while taking the drug.

Here’s why that matters: if a condition occurs naturally in 5% of obese adults, it will appear in FAERS data for a weight loss drug used by obese adults. Some of those events will happen coincidentally because the population has a high background rate. Others might be caused by the drug. FAERS cannot distinguish between the two.

How FAERS Is Used by the FDA

FAERS is a signal-detection tool. When the FDA sees a sudden spike in reports of a specific event, or an unusual pattern, it flags that as a potential safety signal. This signal then prompts a formal safety review. That review uses epidemiological methods (comparing event rates in treated vs. untreated groups, accounting for background rates, etc.) to determine whether a causal link exists.

Many FAERS signals do not result in regulatory action after formal review. Some do. The major GLP-1 safety reviews discussed below all started with FAERS signals, then were investigated formally.

Major FDA Safety Reviews for GLP-1 Medications

Suicidal Ideation and Self-Harm (2023-2024)

The FDA received reports of suicidal ideation in patients using GLP-1 medications. This prompted a formal safety review.

What the FDA found: The review found no causal link between GLP-1 medications and suicidal ideation.^[1] The FDA determined that the FAERS reports did not establish an elevated risk compared to background rates in the population being treated. The FDA published a safety communication in 2024 with these findings.

What this means for you: Suicidal ideation should be monitored during any treatment, and you should contact your provider immediately if you experience suicidal thoughts. However, GLP-1 medications themselves have not been found to increase that risk.

Aspiration During Anesthesia and Surgery (2023)

The FDA issued a safety communication in 2023^[3] after receiving reports of pulmonary aspiration during anesthesia procedures in patients on GLP-1 medications.

The mechanism is now understood: GLP-1 medications slow gastric emptying (the rate at which your stomach releases food into the small intestine). When a patient is sedated or under general anesthesia without proper fasting protocols before surgery, residual gastric contents can be aspirated, meaning they can be inhaled into the lungs.

What the FDA did: The FDA added labeling guidance and notified anesthesiologists. The American Society of Anesthesiologists (ASA) issued updated guidance^[4] on how to manage patients on GLP-1 medications before surgery.

What this means for you: Before any elective surgery, inform your surgeon and anesthesiologist that you are taking a GLP-1 medication. Follow all fasting instructions carefully. Your provider may recommend pausing the medication before the procedure or taking additional precautions. This is manageable with proper planning. For more detail, see the GLP-1 Surgery and Anesthesia page.

Ileus (Intestinal Obstruction) (2023)

FAERS reports described ileus, meaning an acute or prolonged blockage of intestinal movement, in GLP-1 patients. The FDA and European Medicines Agency (EMA) conducted reviews.

What was found: The EMA updated GLP-1 labeling to include ileus as a potential adverse event. Severe constipation that escalates to intestinal obstruction can occur, likely related to GLP-1’s effects on gut motility.

What this means for you: This is distinct from ordinary GLP-1-related constipation, which is common and manageable with hydration and fiber. Ileus is rare and represents severe, persistent intestinal dysfunction. If you develop severe abdominal distension, inability to pass stool for several days despite laxative use, or acute abdominal pain with nausea and vomiting, contact your provider immediately. Your provider should monitor for signs of severe constipation during treatment.

Gastroparesis (2023)

In 2023, researchers published data in JAMA^[5] showing that GLP-1 users had higher rates of gastroparesis (delayed gastric emptying severe enough to cause symptoms) compared to non-users.

This was an observational study, meaning it compared outcomes in two groups but did not randomize people to medication or placebo. The FDA reviewed the data and issued a safety communication adding gastroparesis to GLP-1 labeling as a potential adverse event.

What this means for you: Pre-existing gastroparesis is now considered a contraindication to GLP-1 use. If you have a history of gastroparesis or chronic stomach problems, your provider should evaluate whether a GLP-1 medication is appropriate. During treatment, delayed stomach symptoms like severe bloating, persistent nausea, or early satiety should be reported to your provider.

Pancreatitis

FAERS reports of pancreatitis have been associated with GLP-1 use since the drugs were first studied. This is one of the longest-standing safety signals.

What the clinical trials showed: Large pivotal trials (STEP 1, SURMOUNT-1) did not show a statistically significant increase in acute pancreatitis in GLP-1 users compared to placebo. The 5-year SELECT trial,^[6] which followed weight loss patients long-term, showed a pancreatitis rate of approximately 0.3%, low in absolute terms but worth monitoring.

What the labeling says: Acute pancreatitis is included as a warning in GLP-1 medication labeling. Prior history of pancreatitis is considered a relative contraindication, meaning your provider should carefully weigh whether the benefits of the medication outweigh the risks for you specifically.

What this means for you: If you have a personal history of pancreatitis, inform your provider before starting. During treatment, pancreatitis presents as severe upper abdominal pain that radiates to the back, often with nausea and elevation of pancreatic enzymes (detectable by blood work). If you develop severe, persistent upper abdominal pain, seek medical attention immediately.

Thyroid Cancer and C-Cell Hyperplasia (Medullary Thyroid Carcinoma Warning)

GLP-1 medications carry a black box warning for medullary thyroid carcinoma (MTC) based on animal studies in rodents.^[7] Those studies showed that GLP-1 receptor agonists caused C-cell hyperplasia (overgrowth of thyroid cells) and, in some cases, medullary thyroid carcinoma.

What human data shows: Large observational studies in humans have not confirmed an elevated risk of thyroid cancer in GLP-1 users. The black box warning remains because of the animal findings, even though human epidemiological evidence has not established a causal link.

What the contraindications are: Medullary thyroid carcinoma and Multiple Endocrine Neoplasia type 2 (MEN2) are absolute contraindications. Your provider should screen your personal and family history for these conditions before prescribing.

What this means for you: If you have a personal or family history of medullary thyroid carcinoma or MEN2, you are not a candidate for GLP-1 medications. If you do not have that history, the FDA black box warning applies, but human evidence does not support an elevated risk. Discuss any personal or family history of thyroid disease with your provider before starting.

What FAERS Does Not Cover: The Compounded Medication Gap

One critical piece of FAERS data to understand: it does not track compounded GLP-1 medications.

FAERS tracks adverse events reported for FDA-approved medications.^[2] Each approved medication has a unique National Drug Code (NDC) number, and reports are linked to that specific product. Compounded medications do not have NDC numbers because they are not FDA-approved products. They are prepared by state-licensed compounding pharmacies and are not tracked systematically in FAERS.

This means there is no equivalent pharmacovigilance system for compounded GLP-1 products. Safety signals that would be detected in FAERS for branded medications are invisible for compounded versions. This is a meaningful distinction you should understand when comparing options.

If you are using a compounded GLP-1 medication, you rely on your provider to monitor for adverse effects and to report problems to you. You do not benefit from the systematic surveillance that FAERS provides for branded medications.

How to Report an Adverse Event

If you experience a serious side effect or adverse event while taking a GLP-1 medication, you can report it to the FDA.^[2]

You can submit a report through MedWatch, the FDA’s adverse event reporting program. You can also contact your provider or the medication manufacturer, and they can submit a report on your behalf.

Reporting is voluntary. Your report will be added to FAERS data, which means it contributes to signal detection and helps the FDA identify patterns that warrant formal safety reviews.

Citations

[1] FDA. “Evaluating Risk of Suicidal Thoughts or Actions in Incretin Mimetic Drugs.” Safety Evaluation. 2024. https://www.fda.gov/drugs/drug-safety-communications/update-fdas-ongoing-evaluation-reports-suicidal-thoughts-or-actions-patients-taking-certain-type

[2] FDA. “FDA Adverse Event Reporting System (FAERS) Public Dashboard.” https://www.fda.gov/drugs/questions-and-answers-fdas-adverse-event-reporting-system-faers/fda-adverse-event-reporting-system-faers-public-dashboard

[3] FDA. “FDA Alert: GLP-1 Receptor Agonist and Aspiration Risk During Anesthesia.” Safety Communication. 2023. https://www.fda.gov/drugs/drug-safety-and-availability

[4] American Society of Anesthesiologists. “Consensus-Based Guidance on GLP-1 Receptor Agonist Use and Perioperative Management.” 2023. https://www.asahq.org/about-asa/newsroom/news-releases/2023/06/american-society-of-anesthesiologists-consensus-based-guidance-on-preoperative

[5] Sodhi M, Loomis TL, Stokes A, et al. “Gastroparesis After Initiation of GLP-1 Receptor Agonist Medications.” JAMA. 2023;330(13):1277-1280. https://pubmed.ncbi.nlm.nih.gov/

[6] Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. “Semaglutide and Cardiovascular Outcomes in Obesity without Previously Diagnosed Cardiovascular Disease.” New England Journal of Medicine. 2023;389(25):2221-2232. https://pubmed.ncbi.nlm.nih.gov/37952131/

[7] FDA. “Prescribing Information for semaglutide for chronic weight management.” Center for Drug Evaluation and Research. 2021. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/215256s000lbl.pdf