Antivenin (Crotalidae) is used in adults and children to treat symptoms of a snake bite from certain species of venomous snakes including rattlesnakes, copperheads, and cottonmouths (Water Moccasins).

CroFab (ovine) may also be used for purposes not listed in this medication guide.

If you receive antivenin (Crotalidae) during an emergency, make sure any follow-up doctor knows you received CroFab (ovine).

You should receive antivenin (Crotalidae) as soon as possible after you first have symptoms of a snake bite (fang marks in the skin with swelling or redness and pain, blurred vision, sweating, increased salivation, vomiting, uncontrolled bleeding, trouble breathing, weakness, loss of muscle control, or numbness in the face or body).

Antivenin (Crotalidae) is injected into a vein by a healthcare provider.

You will be watched closely for at least 60 minutes after receiving the medicine to make sure you do not have an allergic reaction and your symptoms are improving.

You may need to receive additional doses if your symptoms do not improve after the first dose. Your doctor will determine how long to treat you with antivenin (Crotalidae).

Venom from a snake bite can increase your risk of bleeding, which can be severe or life-threatening. Call your doctor or seek emergency medical attention if you have any bleeding that will not stop.

Your doctor will monitor your progress and check for signs and symptoms of blood clots for 2 weeks or longer after you are treated with antivenin (Crotalidae). You may need to be treated again with antivenin (Crotalidae) and with a blood thinner.

You should not use antivenin (Crotalidae) if you are allergic to it, or if you have:

• allergy to papaya or papain, chymopapain, pineapples, sheep, horses, dust mites, or latex.

If possible during an emergency, tell your medical caregivers if you've ever had:

• a bleeding or blood clotting disorder;

• cancer;

• congestive heart failure;

• an overactive thyroid;

• a connective tissue disease such as Marfan syndrome, Sjogren's syndrome, lupus, scleroderma, or rheumatoid arthritis;

• if you are dehydrated;

• if you are malnourished; or

• liver disease.

Antivenin (Crotalidae) is made from the blood or plasma of healthy horses or sheep. Blood and plasma are tested and treated to reduce the risk of it containing infectious agents, but there is still a small possibility it could transmit disease. Ask your doctor about your individual risk.

It is not known if antivenin (Crotalidae) will harm an unborn baby. Tell your doctor if you are pregnant.

It is not known whether antivenin (Crotalidae) passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breastfeeding.

If possible during an emergency, tell your medical caregivers if you are pregnant or breastfeeding.

Make sure any follow-up doctor knows you received this medicine.

In an emergency medical setting, you are not likely to miss a dose.

In a medical setting an overdose would be treated quickly.

Avoid activities that may increase your risk of bleeding or injury. Use extra care while shaving or brushing your teeth.

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your medical caregiver if you feel dizzy, nauseated, light-headed, itchy, sweaty, or have a headache, chest tightness, back pain, trouble breathing, or swelling in your face.

CroFab (ovine) may cause serious side effects. Call your doctor at once if you have:

• bleeding problems--easy bruising or bleeding (nosebleeds, bleeding gums), blood in stool, any bleeding that will not stop;

• pinpoint purple or red spots under your skin;

• fever, swollen glands, joint pain, or not feeling well;

• heavy menstrual bleeding; or

• itching, rash, or skin redness several days after you were treated with antivenin (Crotalidae).

Common side effects of CroFab (ovine) may include:

• itching, rash, redness of skin;

• headache;

• nausea or vomiting;

• swelling in your hands or feet;

• back, muscle, or joint pain; or

• pain in extremities.

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.

Other drugs may affect antivenin (Crotalidae), including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.