There are many risks associated with Reglan. Did you ask your doctor about them? I'm not sure if the drowsiness has anything to do with it, but I know that it has links to depression and that your milk supply (if it was truly a supply issue) will go down once you stop taking the medication. There is a better prescription alternative only available in Canada that doesn't have risks. It is known as Domperidone and many women prefer that over Reglan. If your doctor writes you a prescription for Domperidone, you can actually order it online from a Canadian pharmacy.
Also, I was wondering what made you think you had supply issues? Sometimes you just need to put the baby to the breast more or drink more fluids. Herbal remedies are also very helpful (Blessed Thistle and Fenugreek, 3x a day, 3 capsules of each), as well as pumping every 2-3 hours.
I know I didn't give you the answer you were looking for, but I just wanted to tell you that Reglan is a risky medication and that there might be other, safer alternatives for your situation.
Source(s):
I had low supply issues and refused prescriptions. Using herbs and regular pumping, my supply increased significantly, but not enough. I ended up having to stop because of my hectic work schedule and the distress it was causing my son to be put to the breast.