Re: would metamucil help stop diarrhea/
Is this a new problem? If yes, a vet visit may be indicated.
In humans, fiber is reputed to be helpful in balancing both constipation and diarrhea, so a small amount may help. I've seen it mentioned here more for constipation.
Some considerations (time to play detective!):
How often is the diarrhea occuring? A few times a week? Daily? several times daily?
Was there a food change before the diarrhea started ocurring?
Does your cat go outside where she could be exposed to infectious material, or eat anything contaminated?
Does she eat raw food?
Eat canned food that sits out for a while?
Eat inedible objects?
When was the last time she had bloodwork done?