What causes an ear drum to burst?

Either... ...High pressure behind it, as with an ear infection, or, also with an ear infection, enzymes made by bacteria can eat right through the eardrum. Also, slapping the ear, or poking in it (even with a q-tip) can break through the eardrum.
Pressure. When one gets a middle ear infection, or "otitis media, " fluids build up behind the ear drum. The fluid becomes infected as the bacteria that normally live in our ear fluid multiply. As the infected fluid continues to accumulate, it pushes on the eardrum. As the eardrum is a relatively thin membrane, it can perforate or "burst" from the pressure.
Pressure. When a child gets a middle ear infection (acute otitis media) pressure builds up in the middle ear space which now has pus as well as the air that is normally there. The eustachian tube (tube between the middle ear and nose) is usually blocked with an ear infection and the increased pressure from the pus & air can eventually burst the ear drum, which connects the middle ear to the external ear.

Related Questions

My gf has impacted wax. She also believes that water in her ear will cause the eardrum to burst. She had many ear infections and tubes as a child?

Common problem. Impacted wax can be dissolved by drops available over the counter at most supermarkets or pharmacies. W hen these are too slow, the wax can be removed under direct vision by an ENT. I have also cleaned this out using a water pic, and this does not "rupture" the drum. She can either get this fixed or deal with the poor hearing.Her choice. Read more...

Went to pcp yesterday with sinus infection, bronchitis and ear infection. She sd my right eardrum bulging. Will mountain travel cause it to burst?

Not necesarily. If it does, it would have anyway.Most middle ear infections build up of mucous and pus behind the ear drum.If it ruptures, it often does the first day in aggressive infections. If stable, it actually does not allow pressure effects of altitude to do anything. Read more...