Pulmonary Aspiration and Related Outcomes Associated with Semaglutide and Tirzepatide: A Comparative Pharmacovigilance Study of the FDA Adverse Event Reporting System (FAERS)

Every year, millions of people turn to a specific class of medications to manage type 2 diabetes or to lose weight. These drugs, known as incretin mimetics, work by mimicking natural hormones that tell the body to release insulin after eating. Two of the most prominent members of this family are semaglutide and tirzepatide. While they are highly effective at controlling blood sugar and reducing appetite, they share a powerful side effect: they slow down the stomach. This delay in gastric emptying keeps food in the stomach longer than usual, which helps people feel full but also creates a specific medical risk. If a person taking these drugs needs surgery or falls ill and loses consciousness, the food sitting in their stomach can be regurgitated and inhaled into the lungs. This event, called pulmonary aspiration, can lead to severe pneumonia or even death. Because these medications are so widely used, doctors and safety regulators need to understand how dangerous this risk truly is and whether one drug might be riskier than the other.

To answer these questions, a researcher at Inonu University in Turkey conducted a large-scale review of real-world safety reports. The study focused on the FDA Adverse Event Reporting System, a massive public database where doctors, patients, and manufacturers submit stories about unexpected problems with medications. The researcher looked for reports specifically mentioning pulmonary aspiration or aspiration pneumonia linked to semaglutide or tirzepatide. A critical step in the process involved cleaning the data to ensure accuracy. The researcher found that some reports listed both drugs as suspects, likely because a patient had switched from one to the other or was taking both during a transition period. To prevent these mixed cases from confusing the comparison, the researcher separated them into their own small group, leaving two distinct groups for analysis: one containing only semaglutide reports and another containing only tirzepatide reports.

The final analysis examined 218 total cases of aspiration. The group linked to semaglutide included 132 reports, while the group linked to tirzepatide included 79 reports. The people in these reports were generally older adults, with an average age in the early sixties, and the groups were fairly balanced between men and women. When the researcher looked at the most serious outcomes, the picture was largely similar between the two drugs. In the semaglutide group, about 17 percent of the reported cases resulted in death, and roughly 62 percent required hospitalization. In the tirzepatide group, the numbers were nearly identical, with 16.5 percent of cases ending in death and 53 percent leading to hospitalization. Statistically, these differences were so small that they could easily be due to chance rather than a true difference in safety between the two drugs.

However, the study did uncover one significant difference regarding how the severity of the events was described. While the death and hospitalization rates were comparable, reports involving tirzepatide were much more likely to be labeled as "life-threatening" by the person filing the report. In the tirzepatide group, nearly 18 percent of the cases carried this designation, compared to only 7.6 percent in the semaglutide group. This suggests that when aspiration occurs with tirzepatide, it may be perceived as more immediately critical or severe, even if the ultimate outcomes of death or hospitalization remain similar. The small group of seven cases where both drugs were reported showed a different pattern, with no deaths or life-threatening labels, though the sample size was too small to draw firm conclusions about that specific scenario.

The researcher suggests that the higher frequency of "life-threatening" labels for tirzepatide could be due to the drug's unique mechanism. Unlike semaglutide, which targets a single hormone receptor, tirzepatide activates two different receptors simultaneously. This dual action might slow down the stomach even more profoundly, potentially leading to larger amounts of retained stomach contents and more acute aspiration events. Alternatively, the difference might reflect a reporting bias. Since tirzepatide is a newer medication, doctors and patients might be more vigilant and more likely to report severe outcomes for it compared to the older, more familiar semaglutide. The study concludes that while both drugs carry a serious risk of pulmonary aspiration with similar rates of death and hospitalization, the heightened severity signals for tirzepatide warrant careful attention. For now, the most important takeaway is that anyone taking these medications needs strict adherence to fasting rules before surgery and close monitoring during acute illness to prevent food from entering the lungs.