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Cemiplimab Side Effects

The most commonly reported side effects of cemiplimab include death, disease progression, and fatigue, based on 2,961 FDA adverse event reports from 2018 to 2025. 3.1% of reports found the drug to be ineffective.

Cemiplimab side effects

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

1
Death5.9%175
2
Disease Progression5.6%166
3
Fatigue5.2%155
4
Off Label Use5.2%155
5
Pyrexia3.7%109
6
Rash3.6%108
7
Dyspnoea3.2%96
8
Drug Ineffective3.1%93
9
Diarrhoea2.8%83
10
Asthenia2.7%81
11
Pneumonia2.7%79
12
Nausea2.6%78
13
Pneumonitis2.6%76
14
Pruritus2.5%75
15
Myocarditis2.2%66

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

Report severity

86.6%Serious2,565 reports
41.1%Hospitalizations1,217 reports
19.1%Fatal567 reports

Seriousness is determined by the reporter, not by OpenClaim.

Cemiplimab drug interactions

Other drugs that appear in adverse event reports alongside cemiplimab. 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
Carboplatin6.8%200
2
Pemetrexed3.4%102
3
Paclitaxel3.4%100
4
Prednisone2.0%58
5
Pembrolizumab1.8%53
6
Ipilimumab1.8%52
7
Cetuximab1.5%43
8
Nivolumab1.4%42
9
Atezolizumab1.3%39
10
Cisplatin1.3%38
11
Atorvastatin-calcium1.3%38
12
Tacrolimus1.2%37
13
Isatuximab-irfc1.1%34
14
Durvalumab1.1%34
15
Bisoprolol-fumarate1.1%33

Taken alongside

1
Acetaminophen6.8%201
2
Aspirin4.2%125
3
Amlodipine3.3%97
4
Levothyroxine-sodium3.2%94
5
Atorvastatin-calcium3.1%93
6
Prednisone3.0%90
7
Bisoprolol-fumarate2.9%85
8
Dexamethasone2.8%82
9
Pantoprazole-sodium2.6%76
10
Omeprazole2.5%75
11
Metformin2.5%74
12
Oxycodone2.2%66
13
Ondansetron2.2%66
14
Metoprolol1.9%57
15
Apixaban1.9%56

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 cemiplimab side effects

24.5% of cemiplimab adverse event reports involve female patients and 38.9% involve male patients. The largest age group is elderly at 67%. These figures reflect who reports side effects, not underlying risk.

Sex

Female24.5%
Male38.9%
Unknown36.6%

Age group

< 20.0%
2–11<0.1%
12–17<0.1%
18–6432.8%
65+67.0%

What is cemiplimab used for

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

Adenocarcinoma Of ColonAdenocarcinoma Of The CervixAnal CancerAngioimmunoblastic T-cell LymphomaActinic KeratosisAdenocarcinomaAdenocarcinoma Of The CervixAdenosquamous Carcinoma Of The CervixAdenosquamous Cell CarcinomaAdjuvant TherapyAnal CancerAnaplastic Thyroid CancerAngiosarcoma MetastaticAstrocytomaB-cell Lymphoma

Showing 15 of 245 indications

Cemiplimab brand names and reporting trend

Cemiplimab is sold under the brand name Libtayo.

Brand names

Libtayo1,517

Quarterly reports (20182025)

20182020202220242025

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

Taking cemiplimab with another medication?

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