I've traveled with Epipens for years. No problems although I do have the original packaging with the Rx. I keep them in a gallon Zip-Loc bag to keep them clean. A year ago the TSA folks would log them in. Now they just look at them.
They see plenty of these things.
I have had problems lately with the TSA folks and Rx eye medications; but that is a different story all together. The eye medications are liquids (in tiny bottles).
I wish the TSA would get its act together! Every time I go through a TSA check point I get a different proceedure and rule thrown at me. Not nice!