What if I missed an entry on medical prescriptions for 2019 ?

Hello,

I e-filed my Federal & AZ State tax returns yesterday only to realize today that I neglected to input an additional $392.00 of prescription drugs. What should I do? I read that an amended return can only be completed by regular mail so how does that work given that my returns have both been accepted already? My wife & I always have enormous medical bills every year, so I imagine that this extra amount would have increased the return. Also, along those same lines, can I take my already filed Fed & State returns to see just how much difference this addition would make?

Thank you very much!

Stephen M.