Will she eat some prunes, dry berries, a small salad with olive oil and vinegar or lemon juice? (olive oil: lubrication)
The Epsom Salts Invincible suggested, work almost immediately. If you can't get her to take it try shaking in very cold water and maybe adding a little lemon juice, it is a little easier on the taste buds.
Noni juice has been said to work for a couple of people that had tried many things before without success.
Post what she's eating and drinking, so that you can get more accurate advise.