 So you want to look at that immediately. Advice for some of the many millions in the U.S. under heat advisories. Some people on certain medications can become more sun-sensitive in extreme heat, says Bradley Phillips, the University of Florida College of Pharmacy. If you have a small percentage of experiencing headache, confusion, and dizziness, but you have a handful of other medications that do have those small percentages of that side effect, well, those slowly start to add up.