How do you cure an ear infection?

That depends: Often, fluid in the middle ear, behind the eardrum, is not infected and does not need immediate antibiotic treatment. If there is infected fluid in the middle ear, then an oral antibiotic is indicated to eradicate the bacterial source of the infection. If there is a tube in the eardrum, then drops would be useful as well to treat the infection.

Variable: First and foremost, is the diagnosis correct. If the ear drum is bulging with pus behind it, it is probably viral or bacterial in origin and may need an appropriate antibiotic for 5-10 days at most. If there is just painless fluid in the middle ear space, watchful waiting for a period of no more than 2 months. If either the fluid remains longer or if the painful ear persists, surgical drainage.