I'm like... immune to prune juice. To me, it just tastes nasty and it never lets me take a sh_t. Miralax does nothing for me.

Milk of magnesia helps to a degree, although in extreme cases, you can ask your dr about magnesium citrate. DON'T DO IT WITHOUT ASKING YOUR DOCTOR, THOUGH. It made me sh_t for 3 days straight. I'm not exaggerating. (Maybe it's because I drank the entire bottle... lol.) But I did it because I didn't take a sh_t in 8 days and it's dangerous to go that long. (Thanks, Seroquel...)