Avoid a beach-day bummer: Here's how to treat a jellyfish sting

If you’re strolling the beach to beat the heat, beware of what's around your feet – jellyfish that can deliver painful stings.

Jellyfish stings are common in coastal waters during the summer months. About 500,000 people are stung in the Chesapeake Bay area, and 200,000 are stung in Florida every year, according to the National Science Foundation.

Most stings are by chance. People usually get stung while accidentally stepping on a jellyfish on a beach or brushing up against one while swimming, says the Cleveland Clinic, which estimates 150 million people are stung worldwide every year.

Stings can be painful, but most aren't life-threatening. But some can be deadly, such as stings from the box jellyfish. Sting victims need to be monitored and treated immediately if they have difficulty breathing, an allergic reaction or other serious symptoms.

Anatomy of a jellyfish

How painful are jellyfish stings?

Jellyfish have tentacles that contain nematocysts, which are cells that sting. The nematocysts fire harpoon-shaped barbs that contain toxins into the victim, the Australian Academy of Science says.

The entire discharge takes about three milliseconds, according to the Ocean Conservancy. The stings are designed to drive off predators or immobilize prey.

Depending on the type of jellyfish and the number of barbs fired, stings can vary in pain from a bee sting to that of a burn to a red and swollen rash or welt.

How do you treat a jellyfish sting?

You've probably heard lots of advice, sometimes conflicting, on what to do if you're stung by a jellyfish. Here is what the Mayo Clinic in the U.S. and the National Health Service in the U.K. recommend for non-life-threatening stings.

What are symptoms of a jellyfish sting?

According to the Cleveland Clinic, symptoms include:

Most nonlethal jellyfish stings tend to get better within a few hours, but some stings can produce skin rashes or other irritations that can last weeks, according to the Mount Sinai Hospital website. It advises that you contact your health care provider if symptoms persist.

Source: USA TODAY Network reporting and research; Reuters; Mayo Clinic; National Science Foundation; American Red Cross; Cleveland Clinic