What are possible side effects of neomycin?

Common neomycin side effects include: mouth or rectal sores, vomiting and nausea. These side effects may diminish as your body becomes accustomed to treatment. Talk to your doctor if side effects become troublesome.

Seek immediate medical attention by calling 911 if you are experiencing an allergic reaction characterized by difficulty breathing, hives, rash, itching, tight chest or swelling of the mouth, tongue, lips or face.

Other side effects may include bloody stools, seizures, muscle twitching, tingling skin, vaginal discharge or irritation and stomach pain and cramps. Rare side effects include: diarrhea, hearing loss, dizziness, drowsiness, clumsiness, difficulty breathing, decreased urine production, increased thirst, increased gas production, ringing in the ears, skin rash, light-colored stools with a high fat content, unsteadiness and weakness.