Can Moxifloxacin (a fluoroquinolone antibiotic) cause tremors?

Can Moxifloxacin Cause Tremors?

Yes, moxifloxacin can cause tremors as part of its central nervous system adverse effects, and the drug should be discontinued immediately if tremors develop. 1

Evidence from FDA Drug Labeling

The FDA explicitly lists tremors as a recognized CNS adverse effect of moxifloxacin. 1 The drug label warns that fluoroquinolones, including moxifloxacin, are associated with an increased risk of CNS reactions that may include:

• Tremors (specifically mentioned)
• Convulsions
• Nervousness and agitation
• Dizziness and confusion
• Hallucinations
• Depression and suicidal thoughts 1

These CNS reactions may occur following the first dose of moxifloxacin. 1 If tremors or other CNS effects occur, the FDA mandates immediate discontinuation of moxifloxacin and institution of appropriate measures. 1

Clinical Context and Mechanism

Fluoroquinolones as a class can cause various neurological manifestations. Research confirms that fluoroquinolones, including levofloxacin (a closely related agent), have been associated with involuntary movements including tremor, myoclonus, and chorea-like movements. 2 A systematic review of antibiotic-associated tremors specifically identifies fluoroquinolones among the antibiotic classes that can induce tremors. 3

The tremor typically manifests within the first week of treatment, though onset can occur as early as after the first dose. 1, 2

Risk Factors to Consider

Patients at higher risk for developing tremors and other CNS effects with moxifloxacin include:

• Elderly patients, who may be more susceptible to CNS adverse effects 4, 2
• Patients with pre-existing CNS disorders (severe cerebral arteriosclerosis, epilepsy) 1
• Patients with renal impairment, as drug accumulation may occur 2
• Patients taking concurrent medications that lower seizure threshold 1

The American Academy of Neurology recommends using moxifloxacin with caution in elderly patients with CNS disorders, as they are at increased risk of neurological adverse effects. 4

Management Algorithm

When tremor develops in a patient taking moxifloxacin:

1. Immediately discontinue moxifloxacin 1
2. Switch to a non-fluoroquinolone antibiotic based on the original indication and pathogen susceptibility (consider macrolides, tetracyclines, or beta-lactams as alternatives) 5
3. Monitor for resolution of tremor, which typically occurs within 1-4 weeks after discontinuation, though symptoms can persist up to 6 months in some cases 6
4. Consider ECG monitoring if other symptoms are present, as moxifloxacin can cause QTc prolongation 5
5. Avoid future fluoroquinolone use in this patient 1

Important Clinical Caveats

Moxifloxacin should be used only when the benefits exceed the risks in patients with known or suspected CNS disorders. 1 The drug label specifically warns that patients should know how they react to moxifloxacin before operating automobiles or machinery, as CNS effects including tremors can impair mental alertness and coordination. 1

Do not continue moxifloxacin if tremors develop, even if the infection is not fully treated—switch to an alternative antibiotic immediately. 1 The tremor is a warning sign of CNS toxicity that warrants immediate action, not a minor side effect to be tolerated.