Drugs Home > Precautions and Warnings With C1 Esterase Inhibitor

For some people, C1 esterase inhibitor may cause serious complications, including dangerous allergic reactions. Other precautions for C1 esterase inhibitor include warnings for women who are pregnant or breastfeeding. If you have had a stroke or heart attack, tell your healthcare provider before starting this medication.


What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to using C1 esterase inhibitor (Berinert®, Cinryze®) if you have:
Also, let your healthcare provider know if you are:
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
Make sure to tell your healthcare provider about all other medications you are taking, including prescription and nonprescription medicines, vitamins, and herbal supplements.

Specific C1 Esterase Inhibitor Warnings and Precautions

Some warnings and precautions to be aware of prior to using this medication include the following:
  • This medication can cause a severe, life-threatening allergic reaction. The symptoms of an allergic reaction to C1 esterase inhibitor may be similar to the symptoms of hereditary angioedema, the condition the medication is used to treat. Stop using this medicine and seek immediate medical attention if you develop signs of an allergic reaction during or after your injection, such as:
    • Rash
    • Hives
    • Chest tightness
    • Wheezing or trouble breathing
    • Dizziness or faintness
    • Swelling of the face, lips, tongue, or throat
    • A rapid heart rate
    • A bluish tinge to the skin or lips.
  • C1 esterase inhibitor medications have been associated with blood clots and strokes, especially when used in higher-than-recommended doses. Seek immediate medical attention if you develop signs of a stroke or blood clot, such as:
    • Chest pain or pressure
    • Pain, warmth, or swelling in one or both legs
    • Abdominal (stomach) pain or swelling
    • Sudden weakness or numbness, especially on one side of the body
    • A sudden, severe headache
    • Sudden confusion
    • Difficulty speaking or understanding speech
    • Problems with vision
    • Difficulty breathing.
  • If you use a C1 esterase inhibitor to treat a laryngeal (voice box) hereditary angioedema attack, you should seek immediate medical attention immediately after using the medication. Laryngeal attacks can be life-threatening.
  • If you use the medication to treat an abdominal (stomach) attack, let your healthcare provider know afterwards. Other medical problems, such as stomach ulcers or appendicitis, can cause similar symptoms, and your healthcare provider may need to rule out these other possible causes.
  • Because C1 esterase inhibitor is made from human blood, it may contain infectious agents, such as viruses or the agent that may cause Creutzfeldt-Jakob (CJD) disease (a rare brain disease).
  • If you will be traveling, you will need to plan to bring enough C1 esterase inhibitor for treatment while you are away. Talk to your healthcare provider about this before you travel.
  • C1 esterase inhibitor is a pregnancy Category C medication, which means it may not be safe for use during pregnancy, although the full risks are currently unknown (see C1 Esterase Inhibitor and Pregnancy).
  • It is not known whether C1 esterase inhibitor passes through breast milk. Therefore, if you are breastfeeding or plan to start, discuss this with your healthcare provider prior to using the drug (see C1 Esterase Inhibitor and Breastfeeding).
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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