I'm on my seventh day out of 10 with BiaxinXL 500mg for pneumonia. I take 2 pills at supper time and so far so good: only 1 diarrhea 12 hours after the first dose. No metallic taste at all. I do drink a lot of water as is recommended when you have any infection to help your body eliminate it. I sleep well and after only 2 days of treatment my secretions were clearer. I took Advil for the first four days to help me with the side effects of the disease. I take medication exceptionally because,fortunately, I am rarely sick but I will take all of the pills prescribed by my doctor because I don't want to deal with some super resistant bacteria later on.