I take Synthroid so maybe it's specific to the particular brand. I do know that the generic of Synthroid is also a photosensitive medication. There's always some kind of side effect of a medication, isn't there? Let's hope the benefits outweigh the side effects! Something else about Synthroid (I don't know about the others though) is that you can't eat grapefruit for 2 hours before or after you take the meds as the acid counteracts the medication.