85/100 · Critical
Manufactured by Merck Sharp & Dohme LLC
High Serious Event Rate for Pembrolizumab
152,954 FDA adverse event reports analyzed
Last updated: 2026-05-12
PEMBROLIZUMAB is a medication tracked in the FDA Adverse Event Reporting System (FAERS), manufactured by Merck Sharp & Dohme LLC. Based on analysis of 152,954 FDA adverse event reports, PEMBROLIZUMAB has a safety score of 85 out of 100. This score indicates a relatively favorable safety profile, with fewer or less severe adverse events compared to many other tracked medications. The most commonly reported adverse reactions for PEMBROLIZUMAB include MALIGNANT NEOPLASM PROGRESSION, DEATH, DIARRHOEA, FATIGUE, OFF LABEL USE. This page provides a comprehensive breakdown of reported side effects, safety signals, patient demographics, and AI-powered safety analysis for PEMBROLIZUMAB.
Pembrolizumab has a safety concern score of 85 out of 100, placing it in the high concern category based on analysis of FDA adverse event data. The FDA has received approximately 152,954 adverse event reports for this medication, which is primarily manufactured by Merck Sharp & Dohme Llc.
The most commonly reported adverse events include Malignant Neoplasm Progression, Death, Diarrhoea. Of classified reports, 87.1% were designated as serious by the FDA, meaning they involved hospitalization, disability, or other significant medical outcomes. Pembrolizumab reports a high percentage of serious adverse events, particularly deaths and malignancies.
The most common reactions include diarrhea, fatigue, and rash, indicating a broad range of potential side effects. Interactions with other drugs are not well-documented, but patients should be monitored for immune-related adverse events.
Patients taking Pembrolizumab should monitor for the commonly reported side effects and contact their healthcare provider if they experience any unusual symptoms. Drug interactions are not extensively documented, but patients should be monitored for immune-related adverse events such as interstitial lung disease and immune-mediated hepatitis. This analysis is based on voluntary FDA adverse event reports and should not replace professional medical advice.
Pembrolizumab received a safety concern score of 85/100 (high concern). This is based on a 87.1% serious event ratio across 96,510 classified reports. The score accounts for 152,954 total adverse event reports and 100 distinct reaction types. This high score reflects a significant proportion of serious adverse events in the reporting data.
Adverse event reports by sex: Female: 45,404, Male: 45,014, Unknown: 6. The most frequently reported age groups are age 70 (2,446 reports), age 71 (2,416 reports), age 72 (2,391 reports). These demographics reflect reporting patterns and may not represent the full patient population.
Out of 96,510 classified reports for PEMBROLIZUMAB:
The FDA classifies an adverse event as “serious” if it results in death, hospitalization, disability, congenital anomaly, or requires intervention to prevent permanent damage.
Demographics reflect voluntary FDA adverse event reporting patterns and may not represent the full patient population.
Drug interactions are not extensively documented, but patients should be monitored for immune-related adverse events such as interstitial lung disease and immune-mediated hepatitis.
If you are taking Pembrolizumab, here are important things to know. The most commonly reported side effects include malignant neoplasm progression, death, diarrhoea, fatigue, off label use. While many of these may be mild and temporary, you should contact your healthcare provider if any symptoms are severe or persistent. Patients should report any new or worsening symptoms to their healthcare provider immediately. Regular monitoring for immune-related adverse events is crucial, especially for serious reactions. If you experience a serious adverse reaction, seek emergency medical attention immediately or call 911. You can report side effects to the FDA's MedWatch program at 1-800-FDA-1088.
Regulatory oversight is ongoing, with frequent updates to the drug’s labeling to include new safety information.
The FDA has received approximately 152,954 adverse event reports associated with Pembrolizumab. These reports come from healthcare professionals, consumers, and manufacturers through the FDA Adverse Event Reporting System (FAERS). Note that the number of reports does not directly indicate the frequency of side effects, as adverse events are voluntarily reported and may be underrepresented.
The most frequently reported adverse events for Pembrolizumab include Malignant Neoplasm Progression, Death, Diarrhoea, Fatigue, Off Label Use. By volume, the top reported reactions are: Malignant Neoplasm Progression (11,106 reports), Death (5,511 reports), Diarrhoea (5,281 reports). These figures reflect FDA adverse event reports and may not represent the true incidence rate of these side effects in all patients taking Pembrolizumab.
Out of 96,510 classified reports, 84,059 (87.1%) were classified as serious and 12,451 as non-serious. The FDA classifies an event as "serious" if it results in death, hospitalization, disability, or other medically significant outcomes. A higher serious-event ratio warrants closer attention but does not necessarily mean the drug is unsafe.
Adverse event reports for Pembrolizumab break down by patient sex as follows: Female: 45,404, Male: 45,014, Unknown: 6. This distribution reflects reporting patterns rather than actual risk differences between groups. Reporting rates can be influenced by prescribing patterns, disease demographics, and reporting behavior.
The most frequently reported age groups for Pembrolizumab adverse events are: age 70: 2,446 reports, age 71: 2,416 reports, age 72: 2,391 reports, age 67: 2,269 reports, age 69: 2,269 reports. Age-related reporting patterns can reflect both the demographics of the patient population and potential age-related susceptibility to certain side effects.
The primary manufacturer associated with Pembrolizumab adverse event reports is Merck Sharp & Dohme Llc. Multiple manufacturers may produce generic versions of this drug. The manufacturer listed reflects the most frequently reported brand in FDA adverse event data.
Beyond the most common reactions, other reported adverse events for Pembrolizumab include: Pyrexia, Rash, Product Use In Unapproved Indication, Nausea, Decreased Appetite. Less common side effects can still be clinically significant. Patients should report any unusual symptoms to their healthcare provider.
You can report adverse events from Pembrolizumab to the FDA through their MedWatch program at www.fda.gov/medwatch, by calling 1-800-FDA-1088, or by completing Form FDA 3500. Healthcare professionals, consumers, and manufacturers can all submit reports. Reporting helps the FDA monitor drug safety after approval.
Pembrolizumab has a safety concern score of 85 out of 100 (high concern). This score is calculated from the ratio of serious to non-serious adverse events, the diversity of reported reactions, and the overall volume of reports relative to usage. Pembrolizumab reports a high percentage of serious adverse events, particularly deaths and malignancies.
Key safety signals identified in Pembrolizumab's adverse event data include: High rate of deaths and malignancies progression. Significant number of immune-mediated adverse reactions. Common gastrointestinal and dermatological reactions. These signals are derived from patterns in FDA reports and should be discussed with a healthcare provider for personalized assessment.
Drug interactions are not extensively documented, but patients should be monitored for immune-related adverse events such as interstitial lung disease and immune-mediated hepatitis. Always inform your healthcare provider about all medications, supplements, and over-the-counter drugs you are taking before starting Pembrolizumab.
Patients should report any new or worsening symptoms to their healthcare provider immediately. Regular monitoring for immune-related adverse events is crucial, especially for serious reactions.
Pembrolizumab has 152,954 adverse event reports on file with the FDA. The most common reactions include diarrhea, fatigue, and rash, indicating a broad range of potential side effects. The volume of reports for Pembrolizumab reflects both the drug's usage level and the vigilance of the reporting community.
Regulatory oversight is ongoing, with frequent updates to the drug’s labeling to include new safety information. For the most current regulatory information, check the FDA's drug labeling database or consult your pharmacist.
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