You should talk with your healthcare provider prior to taking cyclobenzaprine ER if you have:
- Difficulty passing urine
- Liver disease, such as liver failure, cirrhosis, or hepatitis
- An overactive thyroid (hyperthyroidism)
- Congestive heart failure (CHF)
- An irregular heart rhythm (arrhythmia)
- Had a heart attack recently
- Any allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant (see Amrix and Pregnancy)
- Breastfeeding (see Amrix and Breastfeeding).
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
(Click Precautions and Warnings With Cyclobenzaprine ER to learn more, including information on who should not take the drug.)
Cyclobenzaprine ER works mostly in the brain stem, not in the spinal cord and not directly on the muscles. The medication works only to relieve muscle spasms caused by problems in the muscle; it does not help with muscle spasms caused by problems in the brain or spinal cord.
Cyclobenzaprine ER comes in an extended-release capsule that prolongs the effects of the medication, much longer than regular, short-acting cyclobenzaprine capsules (Flexeril®).