Antivenom is a medicine that is given to stop snake venom from
binding to tissues and causing serious blood, tissue, or
nervous system problems. Side effects
from antivenom can include rash, itching, wheezing, rapid heart rate, fever, and
The use of antivenom depends on how much poison was injected
(envenomation) and the type and size of the snake. Large snakes tend
to inject more venom than smaller snakes do. Antivenom is used for mild,
moderate, and severe envenomations.
Dry bites (no venom injected) do not need to be
treated with antivenom.
Mild envenomation bites may cause mild
symptoms, such as slight bleeding, pain, and swelling at the bite.
Moderate envenomations are more
likely to cause symptoms of severe pain, swelling of the whole limb, and
general feelings of illness, such as nausea, vomiting, and weakness.
Severe envenomation symptoms include severe pain, severe swelling,
difficulty breathing, moderate to severe bleeding, and signs of
For best results, antivenom should be given as soon as possible after
the bite. It is usually given within the first 4 hours
after the snakebite and may be effective for 2 weeks or more after the bite.
Serum sickness is a delayed reaction to receiving antivenom and can occur several days or weeks after treatment. Symptoms of serum sickness include fever, chills, rash, muscle aches, joint aches, itching, and blood in the urine. Call your doctor if you have received antivenom medicine and you now have symptoms of serum sickness.
ByHealthwise Staff Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine Anne C. Poinier, MD - Internal Medicine Specialist Medical ReviewerSean P. Bush, MD, FACEP - Emergency Medicine, Envenomation Specialist