Morphine Sulfate SR Side Effects: i know someone that took 8mg of morphine in less then 1 1/2 hours http://www.medications.com/effect/view/17429 i know someone that took 8mg of morphine in less then 1 1/2 hours. and his side effects were he passed out and his heart rate went down to a 31. WHy??????????????????????? i have taken 400mg of morphine today and I could barely claim a b Fri, 11 Sep 2009 00:16:47 -0400 http://www.medications.com/effect/view/17429?item=22910 i have taken 400mg of morphine today and I could barely claim a buzz. He is allergic. http://www.medications.com/effect/view/17429?item=22910