The correct spelling depends on whether you’re using British or American English: “diarrhoea” is the British spelling, and “diarrhea” is the American spelling.

British vs American spelling

  • In British English (UK, Australia, India, etc.), the word is spelled diarrhoea.
  • In American English (USA, Canada in many contexts), it’s spelled diarrhea.

Both are correct in their respective varieties of English; it’s just a regional difference, like “colour” vs “color”.

How to remember it

A common trick is to break it down:

  • Diarrhoea (British): Think “dia-rr-hoea” — double “r”, then “hoea” at the end.
  • Diarrhea (American): Think “dia-rr-ea” — double “r”, then “ea” at the end.

Some people use mnemonics like:

  • “Dash In A Real Rush, Hurry Or Else Accident” (for diarrhoea).
  • Or simply: “It’s a real rush, so double the R”.

Common misspellings to avoid

People often misspell it as:

  • Diarrea / diarhea (only one “r”).
  • Diareah / diarreah (wrong order of “a” and “e”).
  • Diarrha / diarrhaea (missing the “e”).

The key is the double “r” and the “ea” (or “hoea”) ending.

In medical/health contexts

In medical writing, both spellings are accepted, but it’s best to stick to the local standard:

  • UK/Australian medical texts usually use diarrhoea.
  • US medical texts and dictionaries (like Merriam‑Webster) use diarrhea.

If you’re writing for a general audience, pick one spelling and use it consistently.

Bottom line:

  • British English: diarrhoea
  • American English: diarrhea

Information gathered from public forums or data available on the internet and portrayed here.