Hello.
I have taken Reglan. It will help increase milk supply but needs to be taken daily for an extended period of time. The drug is usually used for stomach problems and the recommended duration for stomach problems is 120 days. I took it for nearly 8 months. There are side effects. It causes drowsiness, which I did gradually adapt to. It can also cause anxiety/depression and irritability and the manufacturer will give you a list of other problems it could possibly cause that's a mile long. Aside from those I mentioned I didn't have any other problems. The amount of the drug that gets through the breastmilk to the baby is minimal, and significantly less than what they would get being treated for spitting up.
I have heard that on occassion, for no apparent reason when a baby is 3 or 4 months old milk supply will decrease. Reglan is supposed to work particularly well in this circumstance. Decrease in supply can also happen with the use of birth control.
The effective dose is 10mg - 20mg from 1 - 4 times a day; start with one, if you don't see an increase, twice a day, etc., until you see an increase. Most doctors don't know how to prescribe Reglan for this purpose, including OBs. I could feel it when I hit the right dose. My breasts were sort of tender like they are just before milk comes in, then my supply increased.
If your doctor is willing, Domperidone (Motilium) is better because it lacks the side effects on the mother. The drug usually has to be made up at a compounding pharmacy however, and though it is known to increase milk supply as well, its manufacturer does not back its use for such.
There are also over the counter supplements your friend can try. Fenugreek in combination with Blessed thistle. You can get these in capsule or tea form at places like Sunflower Market, Whole Foods Market, etc.. I took these also for several months before going to Reglan. The recommended dose was 3 capsules of each, 3 times a day. If it will work for your friend, she should see results within a week. It worked for me within 24 hours, while it worked, though some women take longer, and some don't respond at all. I don't recommend the tea-- it tastes terrible, and the dosage is smaller.
As with any medication, there are possible risks. I would advise your friend to do some research on her own. She might also benefit from picking up the book, The Ultimate Breastfeeding Book of Answers by Jack Newman, M.D.. It was the best reference I found.