What Are The Uses And Side Effects Of Plan B Pill?

I recently took the Plan B pill I received from planned parenthood. They didn't mention anything about other drugs that might effect it, and I didn't think to mention I was currently on the Medifast diet. I was researching online and saw the warnings on drugs that might effect the outcome. Would Medifast or my omega 3 and digestive vitamins affect the ability for Plan B to work?