Hi, Thank you for your query. I can understand your concerns. Prozac (fluoxetine) is a selective serotonin reuptake inhibitors (SSRI) antidepressant. Flexeril (cyclobenzaprine) is a muscle relaxant used to treat skeletal muscle conditions such as pain or injury Fluoxetine together with cyclobenzaprine. Combining these medications can increase the risk of a rare but serious condition called the serotonin syndrome, which may include symptoms such as confusion, hallucination, seizure, extreme changes in blood pressure, increased heart rate, fever, excessive sweating, shivering or shaking, blurred vision, muscle spasm or stiffness, tremor, incoordination, stomach cramp, nausea, vomiting, and diarrhea. Serotonin syndrome is unlikely to occur with single dose of each drug. The serotonergic toxicity of SSRIs increases with dose, but even in over-dose it is insufficient to cause lethal or near lethal reaction from serotonin syndrome in healthy adults Contact your doctor in case ,you develop any of the symptoms. Regards Dr. T.K. Biswas M.D. Mumbai