OpenClaim

Pembrolizumab Side Effects

The most commonly reported side effects of pembrolizumab include malignant neoplasm progression, death, and diarrhoea, based on 96,898 FDA adverse event reports from 2014 to 2025. 2.5% of reports found the drug to be ineffective.

Pembrolizumab side effects

Percentages show how often each reaction appears relative to total reports for pembrolizumab.

1
Malignant Neoplasm Progression11.5%11,109
2
Death5.7%5,525
3
Diarrhoea5.5%5,304
4
Fatigue4.9%4,790
5
Off Label Use4.6%4,421
6
Pyrexia3.8%3,650
7
Rash3.5%3,420
8
Product Use In Unapproved Indication3.5%3,388
9
Nausea3.5%3,364
10
Decreased Appetite3.2%3,119
11
Hypertension3.1%2,983
12
Hypothyroidism2.8%2,691
13
Asthenia2.7%2,614
14
Product Use Issue2.5%2,454
15
Drug Ineffective2.5%2,420

These are voluntary reports and do not establish that pembrolizumab caused these reactions.

Report severity

87.1%Serious84,413 reports
42.1%Hospitalizations40,778 reports
18.2%Fatal17,595 reports

Seriousness is determined by the reporter, not by OpenClaim.

Pembrolizumab drug interactions

Other drugs that appear in adverse event reports alongside pembrolizumab. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Lenvatinib-mesylate18.3%17,763
2
Carboplatin15.9%15,418
3
Pemetrexed9.7%9,447
4
Paclitaxel9.1%8,784
5
Cisplatin3.4%3,276
6
Axitinib3.3%3,198
7
Enfortumab-vedotin-ejfv2.8%2,686
8
Cyclophosphamide2.4%2,318
9
Fluorouracil1.8%1,780
10
Gemcitabine1.8%1,739
11
Bevacizumab1.6%1,544
12
Doxorubicin-hydrochloride1.5%1,444
13
Epirubicin-hydrochloride1.2%1,194
14
Nivolumab1.2%1,177
15
Oxaliplatin1.2%1,143

Taken alongside

1
Carboplatin4.1%3,965
2
Levothyroxine-sodium4.0%3,855
3
Acetaminophen3.6%3,479
4
Amlodipine3.5%3,411
5
Ondansetron2.7%2,569
6
Dexamethasone2.4%2,343
7
Paclitaxel2.3%2,239
8
Atorvastatin-calcium2.3%2,214
9
Aspirin2.2%2,151
10
Omeprazole2.2%2,131
11
Pantoprazole-sodium2.0%1,986
12
Oxycodone1.9%1,839
13
Prednisone1.8%1,728
14
Pemetrexed1.7%1,663
15
Folic-acid1.7%1,660

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports pembrolizumab side effects

47.0% of pembrolizumab adverse event reports involve female patients and 46.7% involve male patients. The largest age group is elderly at 56%. These figures reflect who reports side effects, not underlying risk.

Sex

Female47.0%
Male46.7%
Unknown6.3%

Age group

< 2<0.1%
2–11<0.1%
12–170.2%
18–6444.2%
65+55.5%

What is pembrolizumab used for

Conditions and purposes for which patients were taking pembrolizumab when the adverse event was reported.

Acinic Cell Carcinoma Of Salivary GlandAcoustic NeuromaAcral Lentiginous MelanomaAcral Lentiginous Melanoma Stage IAcral Lentiginous Melanoma Stage IiAcral Lentiginous Melanoma Stage IiiAcral Lentiginous Melanoma Stage IvActinic ElastosisActinic KeratosisAcute Biphenotypic LeukaemiaAcute Lymphocytic LeukaemiaAcute Lymphocytic Leukaemia RecurrentAcute Lymphocytic Leukaemia RefractoryAcute Myeloid LeukaemiaAcute Myeloid Leukaemia Recurrent

Showing 15 of 1,745 indications

Pembrolizumab brand names and reporting trend

Pembrolizumab is sold under the brand name Keytruda Qlex.

Brand names

Keytruda Qlex44,607

Quarterly reports (20142025)

20142016202020242025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking pembrolizumab with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.