Kalbitor Side Effects Center

Last updated on RxList: 1/6/2021
Kalbitor Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Kalbitor?

Kalbitor (ecallantide) Injection is a human plasma kallikrein inhibitor used to treat attacks of hereditary angioedema (an immune system disorder) in people who are at least 16 years old. Kalbitor is not a cure for hereditary angioedema.

What Are Side Effects of Kalbitor?

Common side effects of Kalbitor include:

  • injection site reactions (bruising, itching, redness, swelling of the skin, pain, rash, or irritation)
  • nausea
  • vomiting
  • stomach pain
  • fever
  • stuffy nose
  • headache
  • diarrhea
  • tired feeling, or
  • sore throat

Dosage for Kalbitor

The recommended dose of Kalbitor is 30 mg (3 mL), administered subcutaneously in three 10 mg (1 mL) injections.

What Drugs, Substances, or Supplements Interact with Kalbitor?

Kalbitor may interact with other drugs. Tell your doctor all medications and supplements you use.

Kalbitor During Pregnancy and Breastfeeding

During pregnancy, Kalbitor should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding./p>

Additional Information

Our Kalbitor (ecallantide) Injection Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.


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Kalbitor Consumer Information

Ecallantide can cause a serious allergic reaction within 1 hour after injection. Tell your caregivers right away if you have:

  • chest pain or tightness, fast or weak heartbeat;
  • wheezing, cough, throat irritation, trouble breathing;
  • hoarse voice, tight feeling in your throat, trouble swallowing;
  • swelling of your lips, tongue, or throat;
  • swelling or redness in your face;
  • itching, rash, or hives;
  • flushing (warmth, redness, or tingly feeling);
  • sneezing, runny or stuffy nose; or
  • dizziness, feeling like you might pass out.

An allergic reaction may have the same symptoms as hereditary angioedema. Your caregivers will watch you closely and will quickly treat an allergic reaction.

Common side effects may include:

  • headache;
  • nausea, diarrhea;
  • fever;
  • stuffy nose, sore throat; or
  • skin reactions where the medicine was injected (redness, rash, itching, bruising, swelling).

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.

Read the entire detailed patient monograph for Kalbitor (Ecallantide Injection)


Digestive Disorders: Common Misconceptions See Slideshow
Kalbitor Professional Information


Hypersensitivity reactions, including anaphylaxis, have occurred in patients treated with KALBITOR [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS].

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The safety data described below reflect exposure to KALBITOR in 255 patients with HAE treated with either intravenous or subcutaneous KALBITOR. Of the 255 patients, 66% of patients were female and 86% were Caucasian. Patients treated with KALBITOR were between the ages of 10 and 78 years.

Overall, the most common adverse reactions in 255 patients with HAE were headache (16%), nausea (13%), fatigue (12%), diarrhea (11%), upper respiratory tract infection (8%), injection site reactions (7%), nasopharyngitis (6%), vomiting (6%), pruritus (5%), upper abdominal pain (5%), and pyrexia (5%).

Anaphylaxis was reported in 4% of patients with HAE. Injection site reactions were characterized by local pruritus, erythema, pain, irritation, urticaria, and/or bruising.

The incidence of adverse reactions below is based upon 2 placebo-controlled, clinical trials (EDEMA3® and EDEMA4®) in a total of 143 unique patients with HAE. Patients were treated with KALBITOR 30 mg subcutaneous or placebo. Patients were permitted to participate sequentially in both placebo-controlled trials; safety data collected during exposure to KALBITOR was attributed to treatment with KALBITOR, and safety data collected during exposure to placebo was attributed to treatment with placebo. Table 1 shows adverse reactions occurring in ≥3% of KALBITOR-treated patients that also occurred at a higher rate than in the placebo-treated patients in the two controlled trials (EDEMA3 and EDEMA4) of the 30 mg subcutaneous dose.

Table 1: Adverse Reactions Occurring at ≥3% and Higher than Placebo in 2 Placebo Controlled Clinical Trials in Patients with HAE Treated with KALBITOR

Adverse ReactionsKALBITOR
N=100 n (%) a
N=81 n (%)a
Headache8 (8%)6 (7%)
Nausea5 (5%)1 (1%)
Diarrhea4 (4%)3 (4%)
Pyrexia4 (4%)0
Injection site reactions3 (3%)1 (1%)
Nasopharyngitis3 (3%)0
a Patients experiencing more than 1 event with the same preferred term are counted only once for that preferred term.

Some patients in EDEMA3 and EDEMA4 received a second, open-label 30 mg subcutaneous dose of KALBITOR within 24 hours following the initial dose. Adverse reactions reported by these patients who received the additional 30 mg subcutaneous dose of KALBITOR were consistent with those reported in the patients receiving a single dose.


In the KALBITOR HAE program, patients developed antibodies to KALBITOR. Rates of seroconversion increased with exposure to KALBITOR over time. Overall, 20.2% of patients seroconverted to anti-ecallantide antibodies. Neutralizing antibodies to ecallantide were determined in vitro to be present in 8.8% of patients and were not associated with loss of efficacy.

Anti-ecallantide IgE antibodies were detected at a rate of 4.7% for tested patients, and anti-P. pastoris IgE antibodies were also detected at a rate of 20.2%. Patients who seroconvert may be at a higher risk of a hypersensitivity reaction. The long-term effects of antibodies to KALBITOR are not known.

The test results for the ecallantide program were determined using one of two assay formats: ELISA and bridging electrochemiluminescence (ECL). As with all therapeutic proteins, there is a potential for immunogenicity with the use of KALBITOR. The incidence of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors, including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, comparison of the incidence of antibodies to KALBITOR with the incidence of antibodies to other products may be misleading.

Postmarketing Experience

Similar adverse reactions have been observed postmarketing as described for clinical trial experience. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate frequency or to establish a causal relationship with drug exposure.

Read the entire FDA prescribing information for Kalbitor (Ecallantide Injection)

© Kalbitor Patient Information is supplied by Cerner Multum, Inc. and Kalbitor Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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