Pembrolizumab: adverse event reports filed with FDA

30,990

reports as suspect product

0.2% of all reports · about 2,464 a year

6,212

reports, 12 months to June 2026

5,011 in the 12 months before

95.7%

marked serious by the reporter

89.9% across the class

16.7%

record death among outcomes, as reported

5,167 reports · not verified by FDA

Reports by month, five years

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Pembrolizumab reports recording the termmedian drug in programmed death receptor-1 blocking antibody

1. Malignant neoplasm progression8.6%2,654
2. Off label useused for a purpose or in a way not on the label5.9%1,836
3. Diarrhoealoose or frequent stools5.7%1,780
4. Fatiguetiredness4.5%1,380
5. Nauseafeeling sick3.9%1,213
6. Deaththe patient died; cause not stated by this term3.9%1,204
7. Anaemialow red blood cells3.8%1,166
8. Drug ineffectivethe medicine did not work as expected3.7%1,142
9. Pyrexiafever3.6%1,121
10. Acute kidney injurysudden loss of kidney function3.6%1,110
11. Pneumonitis3.3%1,030
12. Neutropenialow neutrophils, a type of white blood cell3.3%1,014
13. Rashskin rash3%932
14. Product use in unapproved indicationused for a purpose not on the label3%928
15. Pneumonialung infection2.8%877
16. Hypothyroidismunderactive thyroid2.8%873
17. Astheniaweakness or lack of energy2.8%859
18. Colitisinflamed bowel2.8%855
19. Vomitingbeing sick2.7%839
20. Dyspnoeashortness of breath2.5%790
21. Therapy partial responder2.5%784
22. Thrombocytopenialow platelets2.4%751
23. Decreased appetitereduced appetite2.4%750
24. Disease progressionthe disease advanced2.1%656
25. Neuropathy peripheralnerve damage in hands or feet1.9%601
26. Febrile neutropeniafever with low white blood cells1.9%597
27. General physical health deteriorationgeneral decline in health1.8%561
28. Hypertensionhigh blood pressure1.8%560
29. Product use issuea problem in how the product was used1.8%547
30. Pancytopenialow counts of all blood cells1.7%540

Top 30 of 2,461 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 8 drugs in the programmed death receptor-1 blocking antibody class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 225,959 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 22.4% of reports give the United States as the country of the event or reporter.

Reason for use recorded

The indication field is filled in by the reporter and is often blank; shares are of all 30,990 reports.

Drugs most often listed in the same reports

Other products listed in reports where Pembrolizumab is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the programmed death receptor-1 blocking antibody class

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Pembrolizumab as a suspect or interacting product; reports listing it only as a concomitant medication (4,522) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.