Fluid in the ear is usually caused by blocked drainage or trapped fluid behind the eardrum , often after a cold, allergies, or an ear infection. It can also happen from Eustachian tube dysfunction , where the tube that helps drain the middle ear doesn’t open properly.

Common causes

  • Colds or upper respiratory infections can inflame and block the Eustachian tubes, trapping fluid.
  • Allergies and nasal congestion can do the same thing by swelling the passages near the ear.
  • Middle ear infection (otitis media) can cause fluid buildup, and sometimes pressure makes the eardrum leak or burst.
  • Swimmer’s ear or trapped water can leave fluid in the outer ear canal after bathing or swimming.
  • Less often , enlarged adenoids, nasal polyps, smoke exposure, or chronic ear problems can contribute.

When to get checked

If the fluid comes with pain, fever, hearing loss, dizziness, bad-smelling drainage, or lasts more than a couple of weeks , it’s worth seeing a clinician. If you want, I can also explain how to tell whether it’s fluid behind the eardrum vs water in the ear canal.