Let's take a minute to talk about your medication. 

This is gentamicin. It is an antibiotic that treats infections caused by germs called 'bacteria'. It does not treat infections caused by viruses, like the common cold. 

Doses are usually given into a vein. They can also be given as an injection into a muscle. You should tell your caregiver right away if you notice unusual changes to your body, like a rash, itching, or swelling or tingling of your face or mouth. Your caregiver will monitor the site where you get your dose. You can help keep an eye on the area, and report any swelling or pain. 

Most patients tolerate gentamicin well and start feeling better soon. Mild side effects include nausea or a headache. 

As with any medicine, more serious side effects can occur. With gentamicin, this includes kidney problems. To help keep this medicine safe for you, your doctor will follow you closely and order blood tests. It could cause problems with your inner ear and your sense of balance. You should tell your doctor right away if you have dizziness, problems walking, ringing in your ears, or any change to your hearing. In very rare cases, it has caused a permanent loss of hearing, usually of high tones. Call your doctor if you ever have diarrhea that is bloody or that lasts more than 2 days, even if it happens months after your last dose. 

This medicine can be unsafe for babies during pregnancy. Women should talk to their doctors about pregnancy and breastfeeding. 

For best results with gentamicin, you should finish the full course. Otherwise, the infection could return and become hard to treat.