I got a question from someone who said she had both lactose intolerance and a milk allergy. To get the milk out of her system faster she took a variety of substances including prune juice, Metamucil, and Citrucel and even, when she was desperate, magnesium citrate.
My question to you is, what is the best to take? Are they all safe considering my allergy and is prolonged use safe?
Your question really has two different parts.
Normal use of fiber supplements like Metamucil or Citrucel is not harmful. Fiber is different from laxatives (magnesium citrate is a laxative, often used to empty the bowels as prep for a colonoscopy). Laxatives can be overused.
The other part of the question is the one you didn't ask. Is any of this effective? That answer is no. Milk protein is what causes allergic reactions and it enters your system from the small intestine. All you are doing is evacuating your large intestine faster. But by that time the reaction has already been instigated. Nothing you do after will affect it at all.
The only effective method against allergy is to not take the allergen.
I understand the logic behind this. Milk is causing you to feel sick. Getting the milk out of your system faster should make you sick for a shorter time. Makes perfect sense. Or it would if your digestive system really worked that way. Unfortunately, it doesn't.
That's true even for lactose intolerance, where we know that part of the problem comes from the bacteria that naturally live in your large intestine fermenting the lactose that reaches it. You can't flush out all the bacteria even with a laxative. Fiber only stimulates them. (I find that taking two Metamucil capsules produces twice the waste that taking one does. I take Metamucil because I have Irritible Bowel Syndrome and fiber is helpful for that.)
Don't purge. There is no aftercure for either lactose intolerance or milk protein allergy. Avoid.