Refzil O 500mg Tablet is an antibiotic medicine used to treat bacterial infections in your body. It is effective in infections of the lungs (eg. pneumonia), urinary tract, ear, nasal sinus, and throat. It kills bacteria, which helps to improve your symptoms and cure the infection. Refzil O 500mg Tablet may be taken with or without food. You should take it regularly at evenly spaced intervals as per the schedule prescribed by your doctor. Taking it at the same time every day will help you to remember to take it. The dose will depend on what you are being treated for, but you should always complete a full course of this antibiotic as prescribed by your doctor. Do not stop taking it until you have finished, even when you feel better. If you stop taking it early, some bacteria may survive and the infection may come back. It will not work for viral infections such as flu or the common cold. Using any antibiotic when you do not need it can make it less effective for future infections.The most common side effects of this medicine include rash, allergic reaction, nausea, stomach pain, and diarrhea. Taking this medicine along with some food may help to prevent indigestion and upset stomach. Seek emergency medical help if you get a rash, itchy skin, swelling of face and mouth, or have difficulty breathing.Before using it, you should tell your doctor if you are allergic to any antibiotics or have any kidney or liver problems. This medicine is generally regarded as safe to use in pregnancy and breastfeeding if prescribed by your doctor.