Side effects cannot be forecast. If any develop or change in intensity, tell your local doctor as soon as possible. Only your local doctor can determine if it is safe for you to continue taking this generic Avelox. Side effects may consist of abdominal pain, anemia, anxiety, decreased blood pressure, diarrhea, dizziness headache, drowsiness, insomnia, joint and muscle pain, nausea, nervousness, rapid heartbeat, rash, sweating.