Popular ED medications found online include: Viagra sildenafil : As the first FDA-approved PDE5 inhibitor for ED, sildenafil is taken 30 minutes to four hours before sexual intercourse to help achieve and maintain an erection. Your health information should remain between your provider and yourself. However, some states require a live video consultation. People taking nitrates like nitroglycerin Nitrostat or isosorbide mononitrate Imdur should not take PDE5 inhibitors, as doing so could result in a dangerous drop in blood pressure. According to the FDA, generic medications contain the same active ingredients as brand names, meaning there’s no difference in effectiveness or safety. These PDE5 inhibitors may cause headache, flushing, drop in blood pressure, or other adverse effects.tadalafil. erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include headache and indigestion. Tadalafil (Cialis) does interact with some medications. A study found that from to , the median price of Cialis jumped from $ to $ for 30 tablets. Generic brands start at around $ for 30 tablets. Price depends on the strength of. Get started. Try the generic Cialis option (Tadalafil) for the same ED treatment but at a fraction of the cost of Cialis. Speak with a medical professional online today.