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Antivenin (crotalidae) polyvalent Side Effects

Not all side effects for antivenin (crotalidae) polyvalent 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

In addition to its needed effects, some unwanted effects may be caused by antivenin (crotalidae) polyvalent. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when 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

If any of the following side effects occur while taking antivenin (crotalidae) polyvalent, check with your doctor or nurse as soon as possible:

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

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.[Ref]

Nervous system

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


Hematologic side effects have included coagulation disorder and ecchymosis.


Cardiovascular side effects have included hypotension.[Ref]


Dermatologic side effects have included rash and subcutaneous nodule.[Ref]


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.


1. Cannon R, Ruha AM, Kashani J "Acute Hypersensitivity Reactions Associated With Administration of Crotalidae Polyvalent Immune Fab Antivenom." Ann Emerg Med (2008):

2. "Product Information. Crofab (antivenin (crotalidae) polyvalent)" Savage Laboratories, Melville, NY.

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