Fire ant allergy

What it is

Fire ants are one of five insects whose stings are known to cause allergic reactions; the others are honeybees, hornets, wasps and yellow jackets.² Imported fire ants came to the United States from South America decades ago, likely in soil on cargo ships.¹ In the southern United States, ACAAI says, the red or black imported fire ant has become a significant health hazard and may be the number one cause of insect stings.²

Fire ants attack in their own way. Each ant bites and holds on with its jaws, then stings several times.² Fire ants can also sting repeatedly, and when a mound is disturbed, hundreds to thousands of them respond.²

Symptoms it causes

A fire ant sting follows a typical course. Almost everyone stung develops an itchy, localized hive or lump at the sting site, which usually fades within 30 to 60 minutes.² A small blister forms within four hours, and by 8 to 24 hours it usually looks filled with pus-like material. ACAAI explains that what is seen is really dead tissue.² Once healed, these spots may leave scars.²

How severe a fire ant sting reaction is varies from person to person.² For insect stings in general, ACAAI describes a large local reaction as swelling that extends beyond the sting site, generally more than 3 inches around it, which usually peaks two to three days after the sting and can last a week or more.²

The most serious reaction to a sting is an allergic one. It causes symptoms away from the sting, such as hives, itching and swelling in other areas, stomach cramps, vomiting or diarrhea, tightness in the chest and difficulty breathing, or swelling of the tongue or throat.² Anaphylaxis, an even more severe allergic reaction, can begin within minutes of a sting and may be life-threatening.²

People who have had an allergic reaction to an insect sting have a 60% chance of a similar or worse reaction if stung again.² An allergist can test for sting allergy; intradermal skin tests show whether someone is allergic to insect stings.³

Where it’s found

Imported fire ants are found throughout the southern United States and in parts of California and Puerto Rico.¹ USDA puts the infested area at more than 367 million acres, in Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia and Puerto Rico.¹ They spread to new areas on their own and by hitchhiking on agricultural goods.¹

Stings often come in numbers, because a disturbed mound sends out hundreds to thousands of ants.² ACAAI says stinging insects as a group are most active during late spring, summer and early fall.² It also notes that insect repellents do not work against stinging insects.²