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 body aches.
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 shock.
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.