Hi, My Dr had me take 20mg Cialis and cut all of them in half and take 1 every 3 days. The 2nd day after taking a half tablet, I developed sever back muscle pains and inside the back of my chest, also my Ziatic nerve inflamed and ached non-stop and I could not get my breath when trying to lift anything. I was also on PB meds.Mylan 5mg once a day