Most Common Effects

• In clinical trials with Avelox, the most common side effects included nausea, diarrhea and dizziness, occurring between two and six percent of participants.
  
  

Additional Side Effects

• Additional possible side effects include abdominal pain, abnormally-low blood pressure, anemia, drowsiness, headache, increased perspiration, insomnia, joint or muscle pain and nervousness.
  
  

Black Box Warning

• The U.S. Food and Drug Administration requires a black box warning on all flouroquinolone antibiotics, including not only Avelox, but Cipro, Levaquin and others. This warning addresses the risk of tendon rupture associated with these drugs, which can cause long-term or permanent disability.
  
  

Psychological Side Effects

• Potentially serious, although rare, psychological side effects associated with Avelox include anxiety, depression, hallucinations, nightmares, paranoia, and suicidal thoughts or behavior.
  
  

Other Serious Effects

• Other serious side effects linked to Avelox include bloody diarrhea, fainting, heart palpitations, irregular heartbeat and seizures. Liver problems also can develop, with symptoms of jaundice and dark urine.