The most common symptoms of erectile dysfunction include difficulty achieving or maintaining an erection and reduced sexual desire. Some people opt for a lower daily dose. What does this mean? Side Effects Common side effects of Cialis include the following: Headache. The substance is the same under both trade names. Cialis can be taken with or without food. This ensures the medication is always in the person’s system and allows for spontaneous sexual activity without planning dosing times.The price of tadalafil may depend on the strength. Tadalafil comes in strengths of milligrams (mg), 5 mg, 10 mg, and 20 mg. As with other drugs, the cost of tadalafil depends on several factors. Tadalafil is the generic version of Cialis and is typically lower in cost. Share on Pinterest. The price for tadalafil is $ per month, while Cialis is $ $ Get free savings.