Some common side effects of this drug include: Nausea, Vomiting, Diarrhea Keep in mind that your doctor has advised you this medicine as its benefits outweigh the side effects. However, if you start to notice any of the following serious but rare side effects, get medical help right away: Dark urine, Persistent nausea, Stomach pain, Abdominal pain, Yellowing of eyes and skin, Easy bleeding, Sore throat, Fever Tell your doctor if you get severe headaches, easy bruising or bleeding or mood swings. This antibiotic may also lead to a very serious (possibly fatal) lung problem so get medical help right away if you have trouble breathing, chest pain, or any other lung problems. Using this medication for a long time can cause oral thrush and vaginal yeast infection. Contact your doctor immediately if you start to notice white patches in your mouth.