Cyclobenzaprine generally begins to work within 20 to 60 minutes after taking a dose. For immediate-release tablets, initial effects are usually noticed within about 30 minutes, peaking at around 4 hours. Extended-release formulations take longer to take effect, peaking about 7 to 8 hours after administration. The muscle relaxant effects typically last for about 4 to 6 hours, though the drug's half-life is longer, averaging around 18 hours but can range from 8 to 37 hours depending on individual factors. The duration and onset can be affected by metabolism, dosage, whether the drug is taken with food, and other medications. Users may feel muscle relaxation and a sense of calm or mild drowsiness as signs the medication is working.
