Can you take ciprofloxacin (Cipro) and tizanidine at different times to minimize interactions?

Ciprofloxacin and Tizanidine Cannot Be Taken Together, Even at Different Times

Concomitant use of ciprofloxacin and tizanidine is absolutely contraindicated, regardless of timing between doses. 1 Taking these medications at different times does not eliminate the dangerous interaction.

Why These Medications Cannot Be Combined

Ciprofloxacin is a strong inhibitor of the CYP1A2 enzyme that metabolizes tizanidine. This interaction:

• Increases tizanidine plasma levels by 7-10 fold 2
• Significantly potentiates tizanidine's hypotensive effects (blood pressure drops of -35 mmHg systolic vs -15 mmHg without interaction) 2
• Dramatically increases sedative effects 2
• Raises risk of serious adverse events including severe hypotension, bradycardia, and syncope 3

Clinical Evidence of Harm

The interaction between ciprofloxacin and tizanidine is well-documented:

• Real-world data shows a 43% increased risk of hypotension when these medications are combined (adjusted odds ratio: 1.43) 4
• FDA Adverse Event Reporting System shows a reporting odds ratio of 28.1 for hypotension when tizanidine and ciprofloxacin are used together 3
• Two fatal outcomes have been reported in the WHO pharmacovigilance database 5

Timing Does Not Eliminate the Risk

This interaction cannot be managed by spacing doses apart because:

1. Ciprofloxacin inhibits the metabolic pathway of tizanidine (CYP1A2) for its entire duration in the body
2. The FDA drug label explicitly states: "Concomitant administration with tizanidine is contraindicated" 1
3. The British Thoracic Society guidelines list tizanidine as a contraindication to ciprofloxacin use 6

Alternative Options

If you need both medications:

1. Replace ciprofloxacin with a non-fluoroquinolone antibiotic that doesn't inhibit CYP1A2
2. Replace tizanidine with another muscle relaxant like baclofen, which can be safely taken throughout the perioperative period 6

Important Warnings

• The interaction is not dose-dependent - even small doses of either medication can cause dangerous effects when combined
• The risk is particularly high in patients with existing cardiovascular conditions, renal impairment, or those taking other medications that affect blood pressure
• Symptoms of toxicity include severe hypotension, bradycardia, excessive sedation, and dizziness

This drug interaction is classified as severe and potentially life-threatening. No adjustment in timing or dosing can make this combination safe.