I guess it really depends upon how severe your menstrual cycle is. The worst part for me is cramps, and I can just take some advil and it's not a big deal... if it's really bad, you could consider Midol, which also has caffeine in it, helping with lethargy (although if you've never taken it before I suggest trying it before exam day). Honestly, I think you'll be so high on corticosteroids that you won't really notice.