I noticed that when I was taking cyclobenzaprine (Flexeril brand name) that one of the side effects was the opposite of premature ejaculation. It almost delayed it to the point of where I could not ejaculate. I did some research online and it seems that they are looking into that drug for those specific qualities. Although this is not the main use of this drug, the main use being a muscle relaxer, maybe talk with your doctor. There may be a chance that small doses of this drug could be prescribed to you to help you with your problem. Good luck!
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Premature Ejaculation problem.