Common Adverse Effects of Levofloxacin
The most common adverse effects of levofloxacin are gastrointestinal disturbances (nausea, diarrhea, constipation), headache, dizziness, and insomnia, occurring in 0.5-3% of patients, with an overall adverse drug reaction rate of approximately 2%. 1, 2
Gastrointestinal Effects
- Nausea is the most frequently reported adverse effect, occurring in 0.5-1.8% of patients, and is the leading cause of treatment discontinuation (0.6%) 1, 2
- Diarrhea and constipation are also common, with diarrhea occurring in ≥3% of patients 2, 3
- Vomiting and bloating occur in 0.5-1.8% of patients 1
- Gastrointestinal adverse events led to discontinuation in 1.4% of patients receiving standard doses 2
Central Nervous System Effects
- Dizziness, insomnia, tremulousness, and headache occur in approximately 0.5% of patients 1
- Headache is among the most common adverse effects (≥3% incidence) 2
- Levofloxacin has one of the lowest potentials for inducing CNS adverse events among fluoroquinolones currently available 3
- Convulsions have been reported but are uncommon 2
Dermatologic Reactions
- Rash, pruritus, and photosensitivity occur in 0.2-0.4% of patients 1
- Levofloxacin has a very low phototoxic potential compared to other fluoroquinolones like sparfloxacin, enoxacin, and pefloxacin 3
Serious but Less Common Adverse Effects
Musculoskeletal Complications
- Tendinitis and tendon rupture are serious complications that led to FDA black box warnings for all fluoroquinolones 1, 2
- Risk factors include age >60 years, concomitant corticosteroid use, and kidney, heart, or lung transplants 2
- Fluoroquinolones exert toxic effects on tendons, cartilage, bone, and muscle 1
Cardiovascular Effects
- QTc prolongation is rare with levofloxacin (1 in 15 million prescriptions) compared to other fluoroquinolones 3
- This represents a significantly better cardiovascular safety profile than sparfloxacin (1-3% with QTc >500 msec) or moxifloxacin 3
Hepatotoxicity
- Hepatic abnormalities are very rare with levofloxacin (1 in 650,000 prescriptions) 3
- This is substantially lower than trovafloxacin, which caused 140 cases of hepatic problems including 8 requiring transplantation 3
Neurologic Effects
- Peripheral neuropathy may occur and can be irreversible, requiring immediate discontinuation 2
- Symptoms include pain, burning, tingling, numbness, and weakness 2
Comparative Safety Profile
- Levofloxacin has one of the lowest adverse drug reaction rates among fluoroquinolones at 2%, compared to 2-10% for other agents in the class 3
- The tolerance profile can be considered very good, and better than most, if not all, fluoroquinolones available 3
- Levofloxacin is generally well tolerated with few phototoxic, cardiac, or hepatic adverse events seen with some other quinolones 4
Clinical Considerations
- Discontinuation due to adverse reactions occurs in 4.3% of patients overall, with gastrointestinal effects being the most common reason 2
- The 750 mg dose has a slightly higher discontinuation rate (5.4%) compared to 250-500 mg doses (3.8%) 2
- Adequate hydration should be maintained to prevent crystalluria and cylindruria 2
- Antacids and medications containing divalent cations must be separated from levofloxacin by at least 2 hours to avoid absorption interference 1, 2