Cialis is available as a tablet that’s taken by mouth. Unlike earlier studies, the current research found that subjects on the highest doses of ED medication had significantly lower rates of cardiovascular crises than those on the lowest doses. The table below summarizes the typical dosages for tadalafil: Indications of Tadalafil:. A dose of Cialis can remain effective in the body for up to 36 hours. Cialis Daily tadalafil : This low-dose Cialis works by increasing blood flow to the penis over time, making it easier to have an erection when aroused. How Does Cialis Work? ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed.If you’ve ever looked into getting a medication for erectile dysfunction (ED), you may know that treatment prices can vary. Cialis (tadalafil), for instance, is one of the most popular brand-name ED medications, and it is manufactured by Eli Lilly. Cialis can cost around $ to $ per month out of pocket, depending on the dosage you need.  · Below, we’ll detail nine of the most common tadalafil interactions to keep in mind. 1. Nitrates. Nitrates are used to treat and prevent angina (chest pain) caused by heart disease. Examples include nitroglycerin (Nitrostat), isosorbide mononitrate (Monoket), and isosorbide dinitrate (Isordil).  · The approved dosages of Cialis for ED, BPH symptoms, or both, are between mg and 20 mg a day or as needed. Dosages higher than 20 mg a day haven’t been studied, and it’s not known what.