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. Taking Cialis does not mean you are guaranteed to get an erection. You can take it at least 30 minutes before you want to have sex. Society and culture[ edit ] Marketing[ edit ] Cialis 5mg UK pack of 28 tablets In the United States, the FDA relaxed rules on prescription drug marketing in , allowing advertisements targeted directly to consumers. Resources and support See the Healthy Male site for more information about erectile dysfunction and its treatment. Comparison with actions of other PDE5 inhibitors[ edit ] Sildenafil and vardenafil inhibit PDE6, an enzyme found in the eye, more than tadalafil.heart attack symptoms – chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating. Common tadalafil side effects may include: headache; flushing (warmth, redness, or tingly feeling); nausea, upset stomach; stuffy nose; or. muscle pain, back pain, pain in your arms, legs, or back. This is not a complete list of side.  · But on average, its effects start to lessen 2 to 3 hours after you take a dose. The typical dose for once-daily Cialis for ED is milligrams (mg) to 5 mg. When used as needed for ED, the usual. CIALIS for once daily use is a lower dose you take every day. • Do not take CIALIS more than one time each day. • Take one CIALIS tablet every day at about the same time of day. You may attempt sexual activity at any time between doses. • If you miss a dose, you may take it when you remember but do not take more than one dose per day.