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Antivenin (Latrodectus mactans) (By injection)

Antivenin (Latrodectus Mactans) (an-tee-VEN-in (lat-roe-DEK-tus MAK-tans))

Treats symptoms caused by a black widow spider bite.

Brand Name(s):

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive it if you had an allergic reaction to antivenin.

How to Use This Medicine:


  • Your doctor will prescribe your exact dose. This medicine is given as a shot into a muscle or into a vein.
  • A nurse or other health provider will give you this medicine.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have a history of asthma. Tell your doctor if you had an allergic reaction to horses or horse blood products.
  • This medicine may cause a serious allergic reaction called serum sickness. This can happen up to 12 days after you receive this medicine. Talk to your doctor if you have any symptoms that concern you.
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Discomfort, fever, itching, rash, swollen joints or lymph glands
  • Muscle aches or cramps

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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