CroFab Side Effects

Generic Name: antivenin (crotalidae) polyvalent

Note: This page contains information about the side effects of antivenin (crotalidae) polyvalent. Some of the dosage forms included on this document may not apply to the brand name CroFab.

Not all side effects for CroFab may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to antivenin (crotalidae) polyvalent: intravenous powder for solution

Along with its needed effects, antivenin (crotalidae) polyvalent (the active ingredient contained in CroFab) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking antivenin (crotalidae) polyvalent:

More common
  • Unexplained bleeding or bruising
Less common
  • Cough
  • difficulty in breathing
  • difficulty in swallowing
  • dizziness or lightheadedness
  • fast heartbeat
  • fever
  • hives or welts
  • itching of skin
  • joint pain
  • large, hive-like swellings on the eyelids, face, lips, mouth, and/or tongue
  • muscle pain
  • noisy breathing
  • redness of skin
  • shortness of breath
  • skin rash
  • wheezing

Check with your doctor as soon as possible if any of the following side effects occur while taking antivenin (crotalidae) polyvalent:

Less common
  • Areas of pain, redness, and swelling
  • chest pain
  • chills
  • discharge from wound
  • pain, tenderness, and warmth at wound site
  • unusual tiredness or weakness

Some side effects of antivenin (crotalidae) polyvalent may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Nausea
Less common

For Healthcare Professionals

Applies to antivenin (crotalidae) polyvalent: injectable solution


Hypersensitivity reactions have included immediate systemic reactions such as anaphylaxis and shock, characterized by apprehension, flushing, itching, urticaria, edema of the face, tongue, and throat, cough, dyspnea, cyanosis, vomiting, and collapse. Cardiac arrest and death have been reported rarely. Immediate-hypersensitivity reactions occurred in less than 1% of patients with negative skin tests.

Serum sickness may occur 5 to 24 days after administration of antivenin. Symptoms may include fever, malaise, urticaria, lymphadenopathy, edema, arthralgia, nausea, vomiting, meningismus, peripheral neuritis, pain, muscle weakness, and permanent atrophy. Serum sickness may occur within less than 5 days, especially in patients who have previously received horse serum. Its frequency may be related to the number of vials the patient has received.

Nervous system

Nervous system side effects have included meningismus, peripheral neuritis, pain, circumoral paresthesia, general paresthesia, nervousness, and permanent atrophy.


Hematologic side effects have included coagulation disorder and ecchymosis.


Cardiovascular side effects have included hypotension.


Dermatologic side effects have included rash and subcutaneous nodule.


Respiratory side effects have included asthma, cough, and increased sputum.


Musculoskeletal side effects have included myalgia and muscle weakness.


Gastrointestinal side effects have included nausea and anorexia.


Other side effects have included back pain, chest pain, cellulitis, wound infection, and chills.

More about CroFab (antivenin (crotalidae) polyvalent)

Consumer resources

Professional resources

Related treatment guides

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