Cyclobenzaprine, Flexeril®

Brand name

  • Flexeril®

Drug Class

  • Muscle relaxant
  • Blocks the nerve impulses that are sent to the brain


  • Tablet 5 mg
  • Tablet 10 mg


  • 10 mg TID no more than 3 weeks

Adverse Effects

  • May impair your thinking or reactions
  • Be careful if you drive or do anything that requires you to be awake and alert.
  • Drinking alcohol can increase some of the side effects of cyclobenzaprine


  • recent use of MAOi drugs (within the past 14 days) such as
    • isocarboxazid (Marplan)
    • tranylcypromine (Parnate)
    • phenelzine (Nardil)
    • selegiline (Eldepryl, Emsam)
  • recent heart attack
  • arrhythmia
  • congestive heart failure
  • heart block
  • hyperthyroidism

Pregnancy and Breastfeeding

  • FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby.
  • It is not known whether cyclobenzaprine passes into breast milk or if it could harm a nursing baby.
  • Older adults may be more sensitive to the side effects of cyclobenzaprine.


Dose might need adjustment in the following conditions

  • problems with urination
  • enlarged prostate
  • glaucoma
  • liver disease


This document is prepared by the “Mental Health for All” team. This document is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Essentials of Medicine. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.

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