Whether you’re scuba diving, snorkeling, or fishing, you’ll come across different species of fish. But while some species are docile and don’t cause harm upon close contact, this isn’t the case with lionfish.

The beautiful, unique appearance of lionfish can encourage a closer look. But if you get too close, you may have an unpleasant surprise, as they can deliver a sting unlike anything you’ve likely felt before.

Here’s what you need to know about lionfish, as well as what to do if you’re stung by one.

The lionfish is a venomous fish found throughout the Atlantic Ocean, Gulf of Mexico, and the Caribbean Sea. If you’ve never seen one, they’re easily identified by the brown, red, or white stripes that cover their body.

The fish also has tentacles and fan-like fins. Although a beautiful creature, the lionfish is a predatory fish. Its most interesting characteristic is its spine, which contains a venom that it uses as a protective mechanism against other fish.

The venom consists of a neuromuscular toxin that’s similar to cobra venom in toxicity. A lionfish delivers the venom when its spine penetrates the skin of predators, or in some cases, an unsuspecting human.

Coming in contact with lionfish can be dangerous, but they aren’t aggressive fish. Human stings are usually accidental.

A lionfish sting can be very painful. If you’re stung by a lionfish, take care of the wound as soon as possible. Here are a few tips to treat the sting, prevent infection, and reduce pain.

  • Remove pieces of the spine. Sometimes, pieces of their spine remain in the skin after a sting. Gently remove this foreign material.
  • Clean the area with soap and fresh water. If you have a first aid kit, you can also clean the wound with antiseptic towelettes.
  • Control bleeding. Using a clean towel or cloth, apply direct pressure to the wound. This will help your blood clot and stop any bleeding.
  • Apply heat to help the venom break down. Use as much heat as you can tolerate without burning yourself. If you’re snorkeling, swimming, or fishing in an area where lionfish live, prepare for the possibility of an accidental sting: Bring hot water in a thermos or put a reusable heat pack in your marine first aid kit. Just make sure the water or heat pack isn’t too hot! You don’t want to add a burn on top of your injury. Keep the temperature of the water below 120°F (48.9°C). Apply heat for about 30 to 90 minutes.
  • Take pain medication. A lionfish sting can be extremely painful, so take an over-the-counter pain reliever to reduce pain. This can include ibuprofen (Motrin) or acetaminophen (Tylenol).
  • Apply a topical antibiotic cream. Then be sure to wrap a bandage around the wound to reduce the risk of infection.
  • Use ice or a cold pack to reduce swelling. Do this after applying the initial heat therapy.
  • Seek medical attention. Some people don’t need a doctor for a lionfish sting. If the sting causes severe pain, though, you might need a stronger pain medication. Infection is also possible if other germs get in under the skin.

The good news is that a lionfish sting isn’t usually life threatening to healthy individuals. The pain level can vary depending on how deep its spine penetrates the skin.

Initial symptoms of a lionfish sting include:

  • throbbing pain
  • swelling
  • bleeding
  • bruising
  • redness
  • numbness

Even though a lionfish sting isn’t likely to kill humans, some people do have complications after being stung.

If you’re allergic to the lionfish venom, you may develop signs of an allergic reaction or anaphylaxis shock. Severe symptoms can include:

Stings may also cause temporary paralysis, nausea, dizziness, and a headache.

If the venom spreads rapidly, or if you’re unable to control swelling, another complication is tissue death due to decreased blood flow. This tends to happen in the fingertips.

Many people recover from a lionfish sting without medical attention or complications. The important thing is to take immediate steps to stop the bleeding, remove the spine, and keep the wound clean.

Pain from a lionfish sting is usually intense for at least the first few hours, becoming less intense over time. It might take up to 12 hours or more for the pain to subside. Swelling can last up to a few days, whereas discoloration or bruising may last up to 5 days.

The lionfish is a beautiful creature with a distinct appearance, but you shouldn’t get too close. While these fish aren’t aggressive, they can sting accidentally if they mistake you for a predator.

If you’re fishing for lionfish, use a hand net and always wear gloves when handling the fish. You’ll need to carefully remove its spine to avoid a puncture — and a painful reminder of your encounter.