Medical Editor: John P. Cunha, DO, FACOEP
CroFab [crotalidae polyvalent immune fab) (ovine)] is an antivenin product used as an anti-venom to bites from certain snakes (e.g., rattlesnakes, cottonmouths/water moccasins, copperheads). Common side effects of CroFab include:
- itching, and
Less common side effects of CroFab include:
- blood clotting problems,
- back pain,
- chest pain,
- low blood pressure,
- loss of appetite,
- muscle pain,
- numbness and tingling, and
Administration of antivenin should be initiated as soon as possible after crotalid snakebite in patients who develop signs of progressive envenomation (e.g., worsening local injury, coagulation abnormality, or systemic signs of envenomation). The recommended initial dose of CroFab is 4 to 6 vials. CroFab may interact with other drugs. Tell your doctor all medications and supplements you use. During pregnancy, CroFab should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.
Our CroFab [crotalidae polyvalent immune fab) (ovine)] 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.
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 clinical practice.
- The most common adverse reactions reported in the clinical studies were urticaria, rash and nausea. Adverse reactions involving the skin and appendages (primarily rash, urticaria, and pruritus) were reported in 12 of the 42 patients (Table 1).
- Of the 19 patients who experienced adverse reactions, 3 patients experienced severe or serious
- The 1 patient who experienced a serious adverse reaction had a recurrent coagulopathy due to envenomation, which required re-hospitalization and additional antivenin administration. This patient eventually made a complete recovery.
- The other 2 had severe adverse reactions that consisted of 1 patient who developed severe urticaria following treatment and 1 patient who developed a severe rash and pruritus several days following treatment. Both patients recovered following treatment with antihistamines and prednisone.
- One patient discontinued CROFAB therapy due to an allergic reaction.
Table 1 Incidence of Clinical Adverse Reactions in Studies of
CROFAB by Body System
|Advers e Reaction||n=42*
Number of Events
|Body as a Whole|
|*Of the 42 patients receiving CROFAB in the clinical studies, 19
experienced an adverse reaction. A total of 26 adverse reactions was
experienced by these 19 patients.
†Allergic reaction consisted of urticaria, dyspnea and wheezing in 1 patient.
In the 42 patients treated with CROFAB for minimal or moderate crotalid envenomations, there were 7 events classified as early serum reactions and 5 events classified as late serum reactions, and none were serious (Table 2). In the clinical studies, serum reactions consisted mainly of urticaria and rash, and all patients recovered without sequelae.
Table 2 Incidence of Early and Late Serum Reactions (Reactions As s ociated with
CROFAB Infus ion)
Number of Events
|Early Serum Reactions|
|Late Serum Reactions|
|*6 of 42 patients experienced an adverse reaction associated with an early serum reaction
and 4 experienced an adverse reaction associated with a late serum reaction. Two
additional patients were considered to have a late serum reaction by the investigator,
although no associated adverse reaction was reported.
**Allergic reaction consisted of urticaria, dyspnea and wheezing in 1 patient.
†Serum sickness consisted of severe rash and pruritus in 1 patient.
Additional Published Clinical Studies Experience
From a literature review of nine publications on CROFAB containing patient exposure data, 15 of 313 (4.8%) patients receiving CROFAB experienced acute hypersensitivity reactions.
The most common signs and symptoms associated with these reactions were rash (10 patients) and wheezing (3 patients). Most reactions were mild, resolved after antihistamine therapy, and did not require discontinuation of antivenom therapy. No patient developed a life-threatening hypersensitivity reaction, required intubation, suffered lasting ill-effect, or died as a result of CROFAB administration.
Follow up data (minimum of six days after treatment) were available in 94 of the 313 patients and delayed hypersensitivity reactions were reported in 10 cases. The most common signs and symptoms of delayed hypersensitivity were rash (9 patients) and fever (3 patients). Most were mild and treated with antihistamines and steroids.
The following additional adverse reactions have been identified during the post approval use of CROFAB. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to product exposure:
- Delayed allergic reaction manifested by fever, pruritis and/or rash
- Delayed or recurrent coagulopathy or thrombocytopenia
- Failure to achieve initial control
- Recurrent swelling refractory to treatment
- Thrombocytopenia refractory to treatment
- Prolonged hospitalization
- Treatment failure resulting in death
- There were a total of 36 immediate adverse drug reactions reported in 6.1% (15/247) of patients in
the post-marketing retrospective study, including one patient in the severely envenomated group
(3.6%, n = 28) and 13 patients in the mild/moderate severity group (7.2%, n = 181) (not significantly
- There were 11 immediate serious adverse events related to CROFAB administration reported in four patients. The events included two episodes each of hypotension and tongue swelling, and one episode each of chest discomfort, angioedema, bronchospasm, wheezing, tracheal edema, dyspnea, and lip swelling.
- There were 22 immediate non-serious adverse events related to CROFAB administration reported in 12 patients. The events included four episodes each of rash and pruritis, three episodes of urticaria, and one episode each of tachycardia, tachypnea, erythema, swelling, hyperhidrosis, dizziness, headache, musculoskeletal chest pain, chills, feeling cold, and nervousness.
- Delayed hypersensitivity reactions were reported for two patients. In one patient the symptoms occurred 6 days post-dosing, were not serious, and described as hives, itching and epigastric pressure. In the second patient symptoms were not described in the medical records and were therefore not captured in this study.
- Recurrent coagulopathy developed in 5 severely envenomated patients and in 6 mild/moderate envenomated patients. In addition, 7 mild/moderate patients experienced delayed-onset coagulopathy. One severely envenomated patient with recurrent coagulopathy experienced medically significant bleeding.
Read the entire FDA prescribing information for Crofab (Crotalidae Polyvalent Immune Fab Ovine)
© Crofab Patient Information is supplied by Cerner Multum, Inc. and Crofab Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.