The general advice and correct advice is not to mix medicines at all for ED. However I’ve mixed stuff with low dose Cialis eg viagra , Levitra , injections etc and have been ok. I would not use a full event dose of any drug on top of daily Cialis. For example I only added 50 mg viagra. Your doctor would advise no so I guess you just stop Cialis for a while ?? Anything with Alprostadil in it left me in agony afterwards with poor results ( caverject , Muse , Vitaros ). Invicorp was amazing and made me feel whole again. Four years post op I’m 100% normal again although on Cialis daily
Good luck