It may be taken with or without food. Your doctor will probably tell you not to take tadalafil if you are taking street drugs containing nitrates. In , Pfizer scientists discovered that sildenafil, which also inhibits the PDE5 enzyme, caused penile erection in males participating in a clinical study of a heart medicine. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist. If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. Knowledge is Power It’s imperative to consult a healthcare professional before starting any medication, including Cialis.Extra 15% off $30 sitewide with code SAVE15; Clip your mystery deal! BOGO 50% off select Walgreens health & wellness. We have good news for you: generic Cialis, used to treat erectile dysfunction (ED) and enlarged prostates, just hit pharmacies. Prices for the generic, known as tadalafil, are more than 50% less than those of brand-name Cialis. As more men are able to afford tadalafil and treat their ED, it’s likely that many will have questions. Valid at all major chains including Walgreens, CVS Pharmacy, Target, WalMart Pharmacy, Duane Reade and 65, pharmacies nationwide. No manufacturer promotions could be found for this medication. Patient Assistance & Copay Programs for Cialis.