Talk to your doctor about which dosing schedule is right for you. Continue to take tadalafil even if you feel well. Tadalafil can be synthesized starting from D – tryptophan methyl ester and piperonal via a Pictet—Spengler reaction. Your doctor will probably tell you not to take tadalafil if you are taking nitrates. Brand names Why is this medication prescribed? Will Cialis be prescription or OTC over-the-counter?The most commonly reported side effects in patients treated with Cialis during the testing of the product were: headache. indigestion. back pain. muscle pain. flushing. stuffy nose. Patients who. 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 g: precio. Cialis, which treats erectile dysfunction and BPH, can cause side effects such as high blood pressure. ( mg, 5 mg, 10 mg, or 20 mg)? Yes, side effects caused by Cialis can vary depending on.