Ototoxicity is inner ear damage that develops as a side effect of taking certain medications. It can cause problems related to hearing and balance, functions your inner ear controls. It may be helpful to think of ototoxicity’s effects in terms of the word’s origins: “Oto” means ear. “Toxicity” means poisoning. Some medicines used to treat infections and cancer, among other conditions, can damage the sensory cells inside your inner ear that help you hear and keep your balance.