I think alot of it depends on your heart rate. My doctor let me take Robutussin, but my heart rate was right under 100 bpm and I was hyper. I think your doctor may be cautios due to the fact that should you have an abnormal reaction, you might sue him. Not to say that you would, but malpractice insurance is enough, without having a lawsuit…Blame it on all those damn sue-happy people!