When I had to take DD2 to the ER last summer, I was worried. The one time she'd been on an antibiotic, she'd been allergic to it. And as she had a raging infection in her toe, and were sent there for a shot of antibiotic, which the doctor didn't have, he wanted her at the Children's Hospital. She also had a high fever. She'd thrown up the Motrin and couldn't keep down water. So they wanted to give her a fever reducer. They had tylenol suppository, but they looked at the ingredients and there was soy in it. They weren't sure if it would effect her "from that end" but they didn't want to overtax her system so they didn't give it to her. They checked every single thing with me before they gave it to her and they wrote every single thing down that they gave her, just in case. There was no food involved though.
When my DH was just in the hospital last week though, I was happy to see rice milk on the menu (and there was a note on the bottom that said they could accomodate any special dietary needs with advance notice).