Substance guides
How long does Flexeril stay in your system?
Published July 5, 2025 · 6 min read · Updated April 2026
Reviewed for accuracy by licensed clinical professionals.
Flexeril (cyclobenzaprine) has a long half-life of 18 hours (up to 33 hours in elderly patients) and is structurally similar to tricyclic antidepressants.
Detection
Urine: 3-8 days. NOT included on standard drug panels. Specialized testing exists but is rarely ordered. Blood: 2-4 days.
False positive risk
Flexeril can cause false positive results for tricyclic antidepressants (TCAs) on immunoassay screens due to structural similarity. Confirmatory testing resolves this.
Abuse potential
While not a controlled substance federally, Flexeril has emerging abuse potential, particularly in combination with other CNS depressants. Some states are considering scheduling.
Frequently asked questions
Does Flexeril show on a drug test?
Not on standard panels, but can cause false positive for tricyclic antidepressants.
How long does Flexeril stay in urine?
3-8 days with specialized testing.
Is Flexeril addictive?
Not highly addictive alone but has abuse potential, especially combined with other sedatives.
Disclaimer: Informational only. Not medical advice. SAMHSA: 1-800-662-4357.