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Generic Name: casirivimab and imdevimab (Regen-Cov) (KAS i RIV i mab and im DEV i mab)
Brand Name: Regen-Cov

Medically reviewed by on March 16, 2021. Written by Cerner Multum.

What is casirivimab and imdevimab?

Casirivimab and imdevimab are experimental medicines being studied for use in treating conditions caused by coronavirus. It is not yet known if casirivimab or imdevimab are safe and effective for treating any condition.

The US Food and Drug Administration (FDA) has authorized emergency use of casirivimab and imdevimab to treat mild to moderate COVID-19 in adults and children at least 12 years old and weighing at least 88 pounds (40 kilograms). Casirivimab and imdevimab is for use only in people who test positive for COVID-19 and have a high risk of symptoms becoming severe enough to need treatment in a hospital or with supplemental oxygen.

The risk of COVID-19 symptoms becoming severe may be higher in people with:

  • a body mass index (BMI) of 35 or higher;

  • chronic kidney disease;

  • diabetes; or

  • a weak immune system (caused by disease or by using certain medicine).

There also may be a higher risk of severe COVID-19 symptoms in adults who are:

There also may be a higher risk of severe COVID-19 symptoms in children (12 and older weighing at least 88 lbs or 40 kg) who have:

  • a BMI at or above the 85th percentile for age and gender;

  • sickle cell disease;

  • a heart problem;

  • a neurodevelopmental disorder such as cerebral palsy;

  • asthma or other chronic breathing disorder needing daily medication to control; or

  • a tracheostomy, gastrostomy, or positive pressure ventilation (not related to COVID-19).

Casirivimab and imdevimab are mixed together into a single solution to be injected into a vein. The mixture of these two medicines is called Regen-Cov.

Casirivimab and imdevimab have not been approved to treat coronavirus or COVID-19. However, these medicines may help prevent the need for emergency medical care or admission to a hospital because of COVID-19. Regen-Cov is not authorized for use in people who are already in the hospital or receiving supplemental oxygen for COVID-19.

Casirivimab and imdevimab may also be used for purposes not listed in this medication guide.


The FDA has authorized emergency use of casirivimab and imdevimab only in people with COVID-19 who are not in a hospital or using supplemental oxygen.

Casirivimab and imdevimab has not been approved to treat coronavirus or COVID-19. It is not yet known if Regen-Cov is an effective treatment for any condition.

Before taking this medicine

Tell your doctor if you have ever had:

  • any serious or chronic illness;

  • any allergies; or

  • if you are pregnant or breastfeeding.

COVID-19 is more likely to cause serious illness or death in a pregnant woman. Not all risks are known yet, but being treated with casirivimab and imdevimab is likely to be less harmful than being infected with COVID-19 during pregnancy.

How is casirivimab and imdevimab given?

Regen-Cov is given as an infusion into a vein. A healthcare provider will give you this injection.

Regen-Cov must be given slowly, and the infusion can take at least 1 hour to complete.

Regen-Cov is usually given as only one dose. The injection should be given within 10 days of when you first started having symptoms of COVID-19.

You will be watched closely for at least 1 hour after the injection, to make sure you do not have an allergic reaction.

Being treated with Regen-Cov will not make you less contagious to other people. Keep using infection control methods such as self-isolation, social distancing, hand-washing, using protective face covering, disinfecting surfaces you touch a lot, and not sharing personal items with others.

Regen-Cov also may not keep you from becoming infected with coronavirus again. Being treated with this drug combination could also affect your body's immune response to a coronavirus vaccine. Casirivimab and imdevimab are still being studied and all of their risks are not yet known.

What happens if I miss a dose?

Regen-Cov is given in a single dose and does not have a daily dosing schedule.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking casirivimab and imdevimab?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Casirivimab and imdevimab side effects

Get emergency medical help if you have signs of an allergic reaction: hives, itching; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your caregiver right away if you have:

  • throat irritation, swelling in your face or throat;

  • fever, chills, sweating, nausea;

  • rash or itching;

  • weakness, dizziness, a light-headed feeling (like you might pass out);

  • wheezing, shortness of breath;

  • chest pain, fast or slow heartbeats, pounding in your neck or ears;

  • headache, tiredness, change in your mental status;

  • muscle pain; or

  • pain, bruising, bleeding, swelling, or skin changes where the medicine was injected.

Call your doctor if you have new or worsening symptoms after the infusion, such as fever, trouble breathing, fast or slow heart rate, confusion, or tiredness.

Less serious side effects may also occur, or you may have none at all. Not all possible side effects are known.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect casirivimab and imdevimab?

Other drugs may affect casirivimab and imdevimab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

More about REGEN-COV (casirivimab / imdevimab)

Professional resources

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.