Fire ants bite with their jaws and can sting several times, injecting venom. The venom can cause a blister. But you shouldn’t pop these blisters.

There are two main species of fire ants in North America, both accidentally imported from South America in the early 20th century: the black fire ant Solenopsis richteri and the red fire ant Solenopsis invicta. Today, they’re found in at least 14 southern U.S. states and Puerto Rico.

When their nest is disturbed, fire ants may swarm and attack. They bite with their jaws and can insert and remove their stingers to sting you several times, injecting venom. The sting is very painful.

The venom can cause a blister and, in some people, a life-threatening allergic reaction.

There are three main types of reaction to a fire ant bite. A person typically experiences one of the three:

  • Itchy hive or bump at the site of the sting: The hive usually goes away within 1 hour but is replaced by a blister within 4 hours. The blister will appear to fill up within 8 to 24 hours.
  • Large localized reaction: The welt is larger than 10 cm in diameter and causes redness and swelling. The skin area is itchy. The reaction lasts 24 to 72 hours.
  • Severe allergic reaction, including anaphylaxis: If you experience symptoms of anaphylaxis, you should inject epinephrine, or an EpiPen, if you have one and call 911 or local emergency services or go to the nearest emergency room immediately.

Although it may be tempting to pop a fire ant blister, it’s best to leave it alone. An open blister comes with the risk of a bacterial infection. If the blister isn’t scratched or broken, the area should heal on its own. The blister may leave a scar.

A fire ant blister should get better in about 1 week on its own. If the area is itchy, you shouldn’t scratch it, as this increases the risk of opening the blister and getting a bacterial infection.

You can treat fire ant bites and stings with home treatment and basic first aid. If the blister bursts or leaks, you may want to take additional steps to prevent infection.

It’s a good idea to start by removing any ants still on your body. Brushing them off may result in greater aggression from the ants, so instead, consider removing each individually with your hand.

When you’re safely away from the ant nest, inspect your skin for symptoms of a reaction. Even if you haven’t had a severe allergic reaction to a fire ant sting, alert those around you to watch out for symptoms of anaphylaxis.

Medical emergency

Call 911 or local emergency medical services or go to the nearest emergency room if you experience the following symptoms after experiencing fire ant bites or stings:

  • difficulty breathing
  • tightness in the throat
  • hoarse voice
  • dizziness
  • fainting
  • drop in blood pressure
  • nausea
  • vomiting
  • diarrhea
  • abdominal pain
  • rapid heart rate

These are all symptoms of anaphylaxis, a potentially life-threatening allergic reaction.

So long as you’re not experiencing symptoms of a severe allergic reaction, you can treat the stings at home.

If there’s no blister or the blister isn’t broken:

  1. Apply a cold compress to the area. This should lower swelling and pain.
  2. Wash the area with soap and water.

If the blister is broken:

  1. Wash the area with soap and water to prevent infection.
  2. Apply an antibiotic cream on top of the broken blister.

If a compress isn’t enough to reduce itching, you may also want to consider a corticosteroid ointment or antihistamine.

Call 911 or your local emergency services if you experience symptoms of anaphylaxis.

Consider seeing a doctor or healthcare professional if you have symptoms of an infection or home treatment doesn’t relieve your symptoms, specifically if:

  • the blister bursts and you wish to prevent infection or if you see symptoms of infection
  • you experience serious discomfort, such as itching and swelling that doesn’t go down with home treatment
  • the area affected by the sting doesn’t heal within 7 days

A doctor may be able to provide prescription treatment or confirm that home treatments are enough to heal the wound.

Fire ants are found in many southern U.S. states. They respond aggressively when their home is disturbed, biting and injecting venom. The result is typically an itchy welt or hive that turns into a blister. This blister should heal on its own in about 1 week.

It’s best not to pop a blister caused by a fire ant sting because the area could become infected. In rare cases, a fire ant sting can cause anaphylaxis, a life-threatening allergic reaction that requires emergency treatment.