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C1-Esterase Inhibitor (Recombinant) Injection

Why is this medication prescribed?

C1-esterase inhibitor (recombinant) is used to treat acute attacks of hereditary angioedema (HAE; an inherited condition that causes episodes of swelling in the hands, feet, face, airway, or intestines) in adults and adolescents 13 years of age or older. C1-esterase inhibitor (recombinant) is in a class of medications called complement inhibitors. It works by replacing C1-esterase inhibitor that is normally produced by the body and that helps control inflammation and swelling.

How should this medicine be used?

C1-esterase inhibitor (recombinant) comes as a powder in a vial to be mixed with a liquid to inject intravenously (into a vein) over a period of about 5 minutes. C1-esterase inhibitor (recombinant) injection is usually used when needed at the start of an HAE attack, according to your doctor's directions. If your symptoms do not respond to an initial dose of C1-esterase inhibitor (recombinant) injection, your doctor may tell you to inject a second dose. If your symptoms do not improve after you inject a second dose, call your doctor. You should not use more than 2 doses in a 24-hour period. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Use C1-esterase inhibitor (recombinant) injection exactly as directed. Do not use more or less of it or take it more often than prescribed by your doctor.

Your doctor or nurse will show you or a caregiver how to mix and inject a dose of C1-esterase inhibitor (recombinant) injection at home. Before you use C1-esterase inhibitor (recombinant) injection for the first time, you and the person who will be giving the injections should read the manufacturer's information for the patient that comes with it. These instructions describe how to mix and inject a dose of C1-esterase inhibitor (recombinant). Be sure that you understand these directions. Ask your healthcare provider if you have any questions about when you should use the medication, where on your body you should inject the medication, how to give the injection, what type of syringe to use, or how to dispose of used needles and syringes after you inject the medication. Always keep a spare syringe and needle on hand.

You should mix the medication right before you plan to inject it. However, you may mix the medication in advance, store it in the refrigerator, and use within 8 hours. Be sure to take the medication out of the refrigerator and allow it to come to room temperature before you inject it.

Always look at C1-esterase inhibitor (recombinant) solution before injecting it. Check that the expiration date has not passed and that the liquid is clear and colorless. The liquid should not contain visible particles. Do not use if it is expired or if the liquid is colored, cloudy, or contains particles.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before using C1-esterase inhibitor (recombinant) injection,

  • tell your doctor and pharmacist if you are allergic to C1-esterase inhibitor (recombinant), other C1-esterase inhibitor products, any other medications, or any of the ingredients in C1-esterase inhibitor (recombinant). Ask your pharmacist for a list of the ingredients. Also tell your doctor if you are allergic to rabbits or any rabbit-related products.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: androgens such as danazol, methyltestosterone (Android 25), or testosterone (Androderm, Jatenzo, Natesto, others) and medications that contain estrogen (including birth control pills). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have an indwelling catheter (a flexible plastic tube that is placed into the bladder to allow the urine to drain out) or if you have been on bedrest or unable to move around for a long time. Also tell your doctor if you have or have ever had atherosclerosis (narrowing of the blood vessels from fatty deposits) or blood clots in the legs, lungs, eyes, brain, or anywhere in the body.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while using C1-esterase inhibitor (recombinant) injection, call your doctor.
  • if you are having surgery or will be on bedrest, tell the doctor that you are using C1-esterase inhibitor (recombinant) injection.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What side effects can this medication cause?

C1-esterase inhibitor (recombinant) injection may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • nausea
  • diarrhea

Some side effects can be serious. If you experience any of these symptoms call your doctor immediately or get emergency medical treatment:

  • hives; rash; itching; difficulty breathing or swallowing; blue lips and skin; swelling of your face, tongue, or throat; sweating; hoarseness; lightheadedness; or fainting
  • warmth, pain, tenderness, or redness in one leg
  • coughing up blood
  • chest pain
  • shortness of breath

C1-esterase inhibitor (recombinant) may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in to protect from light, tightly closed, and out of reach of children. Store unmixed vials of medication in a refrigerator or at room temperature and away from excess heat and moisture (not in the bathroom). Store medication that has been mixed in the refrigerator and use within 8 hours. Do not allow the medication to freeze.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What other information should I know?

Keep all appointments with your doctor and the laboratory.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Ruconest®
Last Revised - 03/15/2022