Centrally acting muscle relaxants treat painful muscle spasms related to spinal cord injury, multiple sclerosis, cerebral palsy, or spasms due to musculoskeletal injury or other acute musculoskeletal disorders. These medications include baclofen, carisoprodol, chlorzoxazone, and cyclobenzaprine. 

Centrally acting muscle relaxants enhance the inhibitory effects of GABA on receptors in the spinal cord, resulting in suppression of hyperactive reflexes. 

Adverse effects of centrally acting muscle relaxants include drowsiness, dizziness, weakness and fatigue that often subside with continued use. Nausea, vomiting, constipation, and urinary retention occur infrequently, but patients should be informed of the possibility of these effects. Withdrawal manifestations can occur if clients abruptly discontinue them after long-term therapy. 

If this is a new prescription, give the lowest effective dose and gradually increase it to minimize adverse effects. Make sure patients take oral doses of the medication with food to decrease gastric irritation. Since constipation is a potential side effect, it is important to drink plenty of fluids and to increase dietary fiber.

If patients need to discontinue the medication after several weeks or months of therapy, make sure to taper the dose with your provider. 

Clients should not take centrally acting muscle relaxers concurrently with monoamine oxidase inhibitors (MAOIs) as this could result in hypotension or increased CNS depression. Cyclobenzaprine is contraindicated for clients taking MAOIs within the past 2 weeks. Use centrally acting muscle relaxants with caution with older adults, children, and other clients who have a severe mental illness, seizure disorder, or have had a cerebrovascular accident. The use of cyclobenzaprine with MAOIs may cause a hyperpyretic crisis and seizures. Serotonin syndrome can happen if cyclobenzaprine is administered to a client taking selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SSNRIs), and tricyclic antidepressants.