Erectile Dysfunction, though, is when your difficulty with getting an erection or staying hard becomes a regular occurrence. Resources and support See the Healthy Male site for more information about erectile dysfunction and its treatment. If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. Mechanism of action[ edit ] Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and the smooth muscle of the corpus cavernosum. It can also interact with many medicines, particularly nitrates used in some types of heart disease and blood pressure medicines.Dosage range: mg to 5 mg. Frequency: once daily, regardless of the timing of sexual activity. Cialis’s recommended dosage when it’s taken as needed for ED is as follows. Dosage range: 5 mg to 20 mg. Frequency: one dose at least 30 minutes before sexual activity, with a maximum of one dose per day*. Roman sells the following versions of Cialis: Generic: available in tablets of 5, 10, and 20 milligrams (mg), starting from $11 Daily Generic: available in doses of and 5 mg at $8 Branded. Cialis® Manufacturer: Eli Lilly: Country of Origin: Unknown: Application: Erectile Dysfunction Agent: Container Type: Blister Pack: Dosage Form: Tablet: Generic Drug Code: Generic Drug Name: Tadalafil: NDC Number: Quantity: 30 Tablets: Strength: 5 mg: UNSPSC Code: