All the ED drugs have warnings about anyone using one and taking "Nitrates". The combo can lead to extremely low blood pressure and death. After I had by-pass surgery and got a Nitrate prescription, my cardiologist warned me about not using Viagra and Nitroglycerin together. I never had to use the Nitro so was fine.
There is also a reaction between grapefruit juice and Cialis. It's well documented on their web site.
Age 60, PSA 2007 4.1, PSA 2008 10.0
Diagnosed April 2008, Biopsy: 6 of 12 cores positive, Gleason 4 + 5 = 9
CT and Bone Scan negative, Open surgery at Shawnee Mission Medical Center May 21, 2008
Right side nerves spared, Radical prostatectomy and lymph node dissection
Cather removed on June 3rd, totally dry on July 9th, pT2c, lymph nodes negative
PSA Sept 28, 2008 0.00, PSA Jan 22, 2009 0.00, PSA June 29, 2009 0.00
ED Status- Currently using Trimix, Levitra daily for increased blood flow.
Noctural Erections have completely returned on a nightly basis, same hardness as before.