“When an ear infection is serious?”

Fever, Headache, neck pain. Otitis media can turn to otitis interna and mastoiditis. The latter is serious

Any ear infection has the potential to become serious. If you have a fever. If you have persistent, intolerable pain. If you have no or minimal hearing in the affected ear, or if you are diabetic, I would recommend you see your primary care physician, urgent care clinic or emergency department .

Rarely. There are infections of the ear canal, the eardrum (TM), and the inner ear. Canal infections often called swimmers' ear but not always associated with swimming. Easily treatable. The latest guidelines to treating otitis media - which I assume you are talking about, recommends (at least in pediatrics) for mild cases not to use antibiotics, as these are often viral. still a lot of debate about this. The distinction between mild, moderate, severe is vague in the 2019 guidelines that came out. The complications of an ear infection are rare, especially if treated with proper antibiotics. but they are as follows; 1. perforation (rupture due to inside pressure) of the eardrum, the tympanic membrane. 2. if a patient is immunocompromised, a serious complication could be sepsis, septic shock. Again, rare for an ear infection to cause this. 3. they can travel to the sinuses, the mastoids, and sometimes even the brain, and cause meningitis. I can't say enough that complications like these are very rare. Most ear infections will resolve on their own or with antibiotics.