Keytruda: adverse event reports filed with FDA

63,638

reports as suspect product

0.3% of all reports · about 5,381 a year

8,465

reports, 12 months to June 2026

9,873 in the 12 months before

84%

marked serious by the reporter

89.9% across the class

19.1%

record death among outcomes, as reported

12,126 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 Keytruda reports recording the termmedian drug in programmed death receptor-1 blocking antibody

1. Malignant neoplasm progression13.8%8,783
2. Deaththe patient died; cause not stated by this term6.4%4,076
3. Diarrhoealoose or frequent stools4.8%3,062
4. Fatiguetiredness4.5%2,842
5. Product use in unapproved indicationused for a purpose not on the label3.9%2,465
6. Rashskin rash3.7%2,378
7. Pyrexiafever3.7%2,364
8. Hypertensionhigh blood pressure3.2%2,010
9. Decreased appetitereduced appetite3.1%2,003
10. Interstitial lung diseasescarring or inflammation of lung tissue3.1%1,960
11. Off label useused for a purpose or in a way not on the label3.1%1,959
12. Product use issuea problem in how the product was used3.1%1,954
13. Hypothyroidismunderactive thyroid2.9%1,823
14. Nauseafeeling sick2.7%1,731
15. Malaisegeneral feeling of being unwell2.7%1,719
16. Astheniaweakness or lack of energy2.4%1,519
17. Renal impairmentreduced kidney function2.2%1,392
18. Dyspnoeashortness of breath2%1,294
19. Arthralgiajoint pain2%1,243
20. Neuropathy peripheralnerve damage in hands or feet2%1,242
21. Platelet count decreasedlow platelet count1.9%1,224
22. Neutropenialow neutrophils, a type of white blood cell1.9%1,212
23. Acute kidney injurysudden loss of kidney function1.9%1,191
24. Pneumonialung infection1.8%1,157
25. Adverse eventan unwanted medical event, type not specified1.8%1,131
26. Pneumonitis1.8%1,129
27. Anaemialow red blood cells1.7%1,079
28. Weight decreasedweight loss1.7%1,066
29. Hepatic function abnormal1.6%1,043
30. Inappropriate schedule of product administrationthe product was taken at the wrong times1.6%1,040

Top 30 of 2,992 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. 33.4% 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 63,638 reports.

Drugs most often listed in the same reports

Other products listed in reports where Keytruda 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 Keytruda as a suspect or interacting product; reports listing it only as a concomitant medication (5,754) 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.