Can you give miramax to a 7yo who is having constipation problems?

Yes. Miralax (polyethylene glycol) is a non-absorbable sugar. It helps with constipation by creating a more concentrated environment in the intestine which draws more fluid into the intestine, thus softening the stool. Because it is not absorbed into the body, it does not act systemically. It is, as a result, safe and effective for almost all children. Discuss with your pediatrician, of course.
Do you mean Miralax (polyethylene glycol) Miralax (polyethylene glycol) is a powdery substance that is often used as a wetting agent for people with slow transit cconstipation. As a product, I much prefer it to the old chocolot flavored mineral oil we used to use or milk of magnesia. It can be part of a good bowel rehab plan for constipation & is well tolerated. Always consult your doc when using even if it is now available without prescription.