If approved, the provider will issue a prescription. That’s not to say there aren’t just as many illegitimate sites. ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Some services offer a subscription option where they’ll send your medications every month at a discount. What Are the Symptoms of Erectile Dysfunction?Cialis and generic tadalafil are available with a prescription only. There is no OTC version, though there have been efforts in recent years to develop a nonprescription version of tadalafil. 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. 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.