Cindy,
When I took Viagra, I noticed a flushing feeling in my head. The top of my head actually hurt . Doc then gave me some Levitra to try and the flushing was better, however what I have noticed is that my head gets very congested (sinuses). With spring allergies this was bad enough for me to stop for a while. It seems to get better the more I take it though.
When I mentioned this @ the last visit, Doc gave me some Cialis samples to try although I haven't used them yet.
I guess everyone is different but these seem to be common side effects.
Wayne