Most men start with and respond well to the 10 mg tadalafil dose. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. Do I need a prescription for Tadalafil? A higher dose of tadalafil is needed if your body does not respond to the recommended dose. Tadalafil will make these symptoms less severe and reduce the chance that prostate surgery will be needed. Tadalafil is the active ingredient in a branded drug called Cialis.Key takeaways: Cialis (tadalafil) is a popular medication used to treat erectile dysfunction. It’s available in tablets ranging from mg to 20mg. It can cost more than $ for a month’s supply, depending on the dosage you need and the pharmacy you visit. You can save more than 90% on the average retail price at certain pharmacies by. TADALAFIL/Cialis (tah DA la fil) treats erectile dysfunction (ED). It works by increasing blood flow to the penis, which helps to maintain an erection. It may also be used to treat . tadalafil. erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side .