Can I drive while taking tizanidine (a muscle relaxant)?

Driving While Taking Tizanidine: Safety Considerations

You should not drive while taking tizanidine due to its significant sedative effects that can impair your ability to operate a vehicle safely. 1

Understanding Tizanidine and Its Effects on Driving

Tizanidine is an α2-adrenergic receptor agonist that functions as a centrally acting muscle relaxant. While effective for treating muscle spasticity, it has several properties that directly impact driving ability:

Key Concerns for Drivers:

1. Sedation and Drowsiness:

   • 48% of patients in clinical studies reported sedation as an adverse event 1
   • 10% of these cases rated the sedation as severe
   • Effects begin within 30 minutes of dosing and peak at 1.5 hours
   • After a 16mg dose, 51% of patients still reported drowsiness 6 hours later

2. Other Driving-Impairing Effects:

   • Dizziness
   • Ataxia (loss of coordination)
   • Lethargy
   • Hypotension (can cause lightheadedness)
   • Potential for syncope (fainting)

FDA Warning and Manufacturer Guidance

The FDA-approved drug label explicitly warns about driving risks:

"Because of the possibility of sedation, patients should be warned about performing activities requiring alertness, such as driving a vehicle or operating machinery." 1

The label further cautions that sedation may be additive when tizanidine is taken with other CNS depressants, including:

• Baclofen
• Benzodiazepines
• Alcohol

Dose-Related Considerations

The sedative effects of tizanidine are dose-dependent:

• At 16mg: 92% of patients reported drowsiness
• At 8mg: 76% of patients reported drowsiness
• At placebo: 35% of patients reported drowsiness 1

Even at lower doses, significant sedation can occur that would impair driving ability.

Special Considerations

Risk Factors for Increased Sedation:

• Elderly patients (higher sensitivity) 2
• Hepatic or renal dysfunction (reduced clearance) 1
• Concurrent use of CYP1A2 inhibitors (increases tizanidine levels) 2, 1:
  • Oral contraceptives (reduces clearance by 50%)
  • Ciprofloxacin
  • Fluvoxamine
  • Acyclovir
  • Amiodarone
  • Verapamil
  • Cimetidine
  • Famotidine

Overdose Risks

Even modest overdoses can cause severe sedation, hypotension, and bradycardia that would make driving extremely dangerous. The lowest dose associated with hypotension was just 28mg in one case report 3.

Practical Recommendations

1. Avoid driving completely when:

   • First starting tizanidine
   • After any dose increase
   • Taking doses higher than 8mg
   • Taking with other CNS depressants

2. If driving is absolutely necessary:

   • Only consider after being on a stable, low dose for several weeks
   • Never drive during peak effect (1-3 hours after dosing)
   • Have someone else available to drive if possible
   • Be aware that even at stable doses, day-to-day variation in effects can occur

Conclusion

While tizanidine is an effective muscle relaxant with therapeutic benefits, its sedative properties make driving unsafe. The FDA label explicitly warns against performing activities requiring alertness, including driving. The risk of sedation, dizziness, and hypotension creates a significant hazard for both the driver and others on the road.