I brought my epi-pens in my carry-on in October. I had the TSA agents visually inspect them because of this little blurb I read on the epi-pen website:
TSA regulations for medications
You may request that your EpiPen Auto‑Injectors be inspected visually rather than X‑rayed since the effects of X‑rays on epinephrine are unknown. Make sure your medication is clearly labeled; you may want to write your name on it as well. It's not necessary, but you may want to also bring a note from your physician explaining that your EpiPen Auto‑Injector contains a medication for anaphylaxis.
I am rather new to the world of epi-pens and had the exact same questions before I traveled. I wasn't sure they would be allowed in my carry-on, which is why I consulted the epi-pen website.