Vardenafil Levitra and Sildenafil both have the downside of being effective for less time than Tadalafil. A lower dose could be taken every day, for example. In fact, the mixture of the two — alcohol and Cialis — can cause a dangerous drop in blood pressure. Tadalafil also takes the same amount of time to take effect as some shorter-acting options, but it provides support for much longer. In comparison, Viagra or generic unbranded Sildenafil will need to be taken about an hour before anticipated sexual intercourse to give the best chance of effectiveness. Tadalafil and Cialis have identical results in clinical trials for their effectiveness.Cialis is often called the “weekend pill” as it’s effects can last up to 36 hours, meaning your sex life can have a certain amount of sponteneity not possible with other . What is Tadalafil (Cialis) used for? Erectile dysfunction Benign prostatic hyperplasia (BPH). Cialis is a popular ED medication. Find out everything you need to know about this doctor-prescribed medication including usage, effectiveness, and safety .