Reviewed on 7/27/2022

What Is Cemiplimab and How Does It Work?

Cemiplimab is a prescription medication used for the treatment of cutaneous squamous cell carcinoma and other types of cancer.

  • Cemiplimab is available under the following different brand names: Libtayo, cemiplimab-rwlc

What Are Side Effects Associated with Using Cemiplimab?

Common side effects of Cemiplimab include:

  • fatigue,
  • rash,
  • diarrhea,
  • itching,
  • nausea,
  • constipation,
  • fatigue,
  • musculoskeletal pain, and
  • decreased appetite

Serious side effects of Cemiplimab include:

  • new or worsening cough, shortness of breath;
  • chest pain, fast or irregular heartbeats;
  • swollen glands;
  • a seizure;
  • severe headache, confusion, hallucinations, eye pain or redness, vision problems (your eyes may be more sensitive to light);
  • severe muscle pain or weakness, neck stiffness;
  • severe stomach pain, nausea, vomiting, diarrhea, bloody or tarry stools;
  • unusual bruising;
  • transplant rejection--mouth sores, stomach pain, feeling sick or uneasy, rash, pain or swelling near your transplanted organ;
  • kidney problems--swelling in your ankles, blood in your urine, little or no urination;
  • liver problems--right-sided upper stomach pain, loss of appetite, drowsiness, easy bruising or bleeding, dark urine, jaundice (yellowing of the skin or eyes);
  • signs of a hormonal disorder--frequent or unusual headaches, dizziness, feeling very tired, mood or behavior changes, hoarse or deepened voice, increased hunger or thirst, increased urination, constipation, hair loss, sweating, feeling cold, weight gain, or weight loss.

Rare side effects of Cemiplimab include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheartedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


Self-examination is important in the detection of skin cancer. See Answer

What Are Dosages of Cemiplimab?

Adult dosage

Injectable solution

  • 50 mg/mL (7-mL single-dose vial)

Cutaneous Squamous Cell Carcinoma

Adult dosage

  • 350 mg IV every 3 weeks

Basal Cell Carcinoma

Adult dosage

  • 350 mg IV every 3 weeks

Non-Small Cell Lung Cancer

Adult dosage

  • 350 mg IV every 3 weeks

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Cemiplimab?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Cemiplimab has no noted severe interactions with any other drugs.
  • Cemiplimab has no noted serious interactions with any other drugs.
  • Cemiplimab has no noted moderate interactions with any other drugs.
  • Cemiplimab has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Cemiplimab?


  • None 

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Cemiplimab?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Cemiplimab?”


  • Infusion-related reactions reported (see Dosage Modifications)
  • Based on cemiplimab’s mechanism of action, it can cause fetal harm when administered to pregnant women
  • Severe and fatal immune-mediated adverse effects
  • May cause a wide variety of immune-mediated adverse effects
  • Programmed death receptor-1 (PD-1) or PD-ligand 1 (PD-L1) inhibitors, including cemiplimab, block the PD-1/PD-L1 pathway, thereby removing inhibition of immune response, potentially breaking peripheral tolerance and induction of immune-mediated adverse reactions
  • Immune-mediated pneumonitis, colitis, hepatitis, endocrinopathies, hypophysitis, hypothyroidism or hyperthyroidism, type 1 diabetes mellitus, nephritis, and dermatologic reactions reported
  • Other immune-mediated adverse reactions involving other systems (eg, neurological, cardiovascular, ocular) were also reported in <1% of patients or were reported with other PD-1/PD-L1 blockers
  • Usually manifest during treatment and after discontinuation treatment; immune-mediated adverse reactions affecting more than one body system can occur simultaneously
  • Immune-mediated dermatologic reactions, including erythema multiforme and pemphigoid, SJS, and TEN were reported; all dermatologic reactions were treated with systemic corticosteroids in clinical trial; ~22% recurrence of reactions after re-initiation of therapy
  • Evaluate clinical chemistries, including liver tests and thyroid function tests, at baseline and periodically during treatment; institute medical management promptly to include specialty consultation as appropriate
  • Complications of allogeneic hematopoietic stem cell transplantation (HSCT)
  • Fatal and other serious complications can occur in patients who receive allogeneic HSCT before or after being treated with a PD-1/PD-L1 inhibitor
  • Transplant-related complications include hyperacute graft-versus-host-disease (GVHD), acute GVHD, chronic GVHD, the hepatic veno-occlusive disease after reduced-intensity conditioning, and steroid-requiring febrile syndrome (without an identified infectious cause)
  • These complications may occur despite intervening therapy between PD-1/PD-L1 blockade and allogeneic HSCT
  • Closely monitor for evidence of transplant-related complications and intervene promptly; consider benefits versus risks of treatment with a PD-1/PD-L1 inhibitor before or after an allogeneic HSCT

Pregnancy and Lactation

  • May cause fetal harm when administered to pregnant females
  • Verify pregnancy status in females of reproductive potential before initiation
  • Advise women of the potential risk to a fetus
  • Contraception
    • Females of reproductive potential: Use effective contraception during treatment and for at least 4 months after the last dose
  • Lactation
    • There are no data regarding the distribution of human milk or the drug’s effect on breastfed children or on milk production
    • Advise women not to breastfeed during treatment and for at least 4 months after the last dose

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