Do you need antivenom after a rattlesnake bite? Medical toxicology expert explains
It’s summer, and that means that more people are enjoying the California outdoors.
Being outside, whether on a hike or just hanging out in the backyard, means an increased chance of encountering a rattlesnake. Seven species of rattlesnake call California home, out of around 50 species of native snakes.
Generally, rattlesnakes just want to be left alone, and will only bite when they feel threatened. According to Dr. Michael Levine, co-chair of the Division of Medical Toxicology at UCLA, about half of snake bites are a result of people trying to handle snakes or getting too close.
Don’t even step over a rattlesnake, Levine advised. “The snakes can lunge about half of their body distance,” he said. Instead, “walk a significant distance around it.”
Snake bites can happen by total happenstance as well, he said. For example, a gardener may not see a snake coiled among the plants.
What should I do after a rattlesnake bite?
No matter how a snake bite occurs, it’s imperative to seek medical attention afterward by calling 9-1-1.
In most cases, a rattlesnake will inject venom with its bite. Only about 25% of the time will a rattlesnake bite be “dry,” or without venom.
While waiting for help, it’s best to elevate the bitten area. According to Levine, no attempt should be made to remove the venom yourself, whether by sucking on the wound or cutting it.
Once you arrive at the hospital and doctors have confirmed the wound has been injected with venom, they will administer antivenom.
How do you get antivenom?
Rattlesnake bites can cause severe pain, rapid swelling, as well as nausea and trouble breathing. Doctors will conduct an exam to decide treatment, said Levine. He emphasized that there is no need to bring the snake along into the hospital for identification. “It doesn’t change what we do,” he said.
Doctors will elevate the wounded area and draw blood for tests.
“If you’re having significant lab abnormalities, like if the blood is very thin, or the platelet count is falling, we would go ahead and give antivenom for that,” Levine said. Doctors would also administer antivenom if the bitten area is extremely swollen.
There are two types of antivenom currently approved by the FDA for rattlesnake bites, CroFab and AnaVip. The vials of antivenom are administered through an IV drip. Levine notes that the antivenoms are fairly similar, but there are some differences on a molecular level between the two and in their longer-term effects.
Is antivenom hard to get?
For a rattlesnake bite, patients can expect to receive around six vials of CroFab to start, or around 10 vials of AnaVip. “The costs are several thousand dollars per vial,” Levine warned. To treat a rattlesnake bite, most people need about 10 vials of CroFab. As for AnaVip, the number is “in the low 20s.”
Insurance tends to cover the cost of antivenom and its administration. But not all hospitals have it on hand. “Here in Los Angeles, maybe half of all hospitals do and half don’t,” Levine said. Antivenom is expensive, and it’s “fairly delicate.” Plus, hospitals don’t want it to expire without being used. So locations without as many snakes might not carry antivenom.
“Hospitals in the foothills and mountains tend to carry them more,” Levine said.
Getting bitten by a rattlesnake is dangerous, but with treatment, it’s usually not deadly. Avoiding rattlesnakes, however, can spare people a lot of pain and money. “Probably about half of all the bites,” said Levine, “could probably be avoided if people don’t do things that (make them) predisposed to being bitten.”
This story was originally published July 7, 2026 at 11:00 AM with the headline "Do you need antivenom after a rattlesnake bite? Medical toxicology expert explains."
