Found: Help! - YA, SyFi, Highschoolers, Time traveling, Medieval

I read a book back in high school, maybe even middle school, so around 2001-2009, and I can't remember the name.

The book was part of a long series (10+ books). It was about a group of high schoolers or young adults who accidentally traveled back to Medieval times.

I remember one part where someone got injured or had a wound or something, and the characters didn't have anything to sterilize their hands or instruments (being Medieval times) so they used wine.

That's all I really remember. It was a great adventure novel and the following books I remember they kept having to go back in time for various reasons. But once I found out it was such a long series, I quit reading it and now I can't remember what it's called anymore.

Could it be the Everworld series by K.A. Applegate? 12 books, first published around 2000, group of teens get transported into a medievalish mythological world, and there is at least one scene where they do a blood transfusion using what tools they have on hand.

>1 adavis5073: More of a long shot, but the Missing series came out in the late 2000s-2010s, 8 books, including a book where they travel to Medieval times (the other books involved other time periods though). I second Everworld as likely your book series, but I wanted to throw this out there too just in case.

EVERWORLD! YES! THANK YOU SO MUCH!

>4 adavis5073: Yay! You're very welcome!