If you suddenly lose your hearing, in one or both ears, it is an emergency; you need medical attention immediately. Now, you might feel a little foolish if you discover that it is only earwax, but there is a small chance that you have experienced something called idiopathic sudden sensorineural hearing loss. This is a rare and often permanent type of hearing loss that needs to be addressed immediately if there is any hope for your hearing to return.
Strictly speaking, a sudden hearing loss occurs over a period of 72 hours or less. Unfortunately, in most cases the cause of the hearing loss is unknown. Some of the suspected causes are infectious processes (a virus is often assumed), or circulatory/metabolic disorders.
Because there is no single or definite cause of sudden hearing loss, the treatments are varied and their effectiveness is often debated. The first step is to see an audiologist who will test your hearing and, depending on the results, refer you to an ear, nose, and throat (ENT) specialist or back to your family doctor.
Should your hearing loss prove to be a true sudden sensorineural hearing loss, the ENT specialist will likely recommend an MRI and, depending on her point of view, experience, and training, will not prescribe a treatment or will prescribe a form of oral corticosteroid, anti-viral or similar.
About two-thirds of sudden hearing loss events recover spontaneously (without treatment), but this is no reason to wait or avoid seeking treatment. There is some evidence that treatment hastens recovery and the diagnostic process will certainly help you understand what is happening and give you some peace of mind.