What happens when you swallow a bug?

Bug Swallow_Large

“I know an old lady who swallowed a fly – I don’t know why she swallowed the fly,” the nursery rhyme goes.

Don’t let the next line – “perhaps she’ll die” – worry you, says Diane Gorgas, MD, director of Emergency Medicine at The Ohio State University Wexner Medical Center and an associate professor of emergency medicine at Ohio State.

Most bugs, including houseflies, usually are OK to ingest, as long as they end up in your esophagus.

“Keep in mind that a number of areas in the world use insects as a major source of protein in their diets,” she says. “So although we don't embrace it here in the United States, there is no danger to eating most bugs.” 

If the bug moves down into your trachea (or windpipe) below your vocal cords, or if it blocks your airway, that’s a different story.

“Coughing will usually expel the bug, but it’s a concern if it moves significantly below the vocal cords,” she says. 

Flies or other arthropods also can cause some problems if they’re carrying bacteria on their bodies, says Carol M. Anelli, PhD, a professor and interim chair of Ohio State’s Department of Entomology.

“Houseflies can mechanically transmit certain bacteria (Shigella) that cause dysentery,” Anelli notes.

The diarrhea, fever and stomach cramps that can show up after being infected with the Shigella bacteria usually clears up in five to seven days.

Anelli also points out that ingesting fleas could be a way to wind up with the double-pored dog tapeworm, a parasite that mainly affects dogs and cats but occasionally is found in humans. For adults, swallowing fleas typically is avoidable, but parents may want to keep the double-pored tapeworm in mind when young children put their mouths on or near pets.

The bugs to really worry about if swallowed are stinging and biting insects, such as bees, wasps, fire ants and some types of caterpillars. 

“If the person has an allergy to the type of insect,” Gorgas says, “this is as dangerous as being stung anywhere else and can cause severe, life-threatening allergic reactions, in addition to the local pain and swelling of a sting or bite.”

And what if you – or, more likely, a curious child – ate a dead bug that may have been killed by insecticide?

Don’t fret, Gorgas says. The amount of insecticide in one bug is so small that the dosage is considered nontoxic.

Just keep in mind that there are three situations in which you should consider visiting your doctor, urgent care or the emergency department:
  • If you’ve been bitten or stung in the mouth and have insect allergies
  • If you have a sudden, severe pain in your chest or abdomen after accidentally swallowing an insect
  • If you have persistent coughing or irritation in your airway after swallowing a bug

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