Tadalafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. Tadalafil has been extensively studied for ED. These are fleeting and usually subside with time. 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. Tadalafil is also used in both men and women to treat the symptoms of pulmonary arterial hypertension to improve your ability to exercise.Cialis 40/20mg, packs of 10 – Pills. The sexual enhancer Cialis is mainly used by men with medically diagnosed erectile dysfunction. This is when the erection is not sufficient for satisfactory sexual intercourse. The drug requires a prescription and is only dispensed in pharmacies against a prescription. Check Price. Pregnancy Birth control needs Breastfeeding Precautions For professionals Drug Images What is Cialis? Cialis is a brand-name prescription medication. It’s FDA-approved to . Cialis. Rather than Viagra’s 50 or mg blue pills, Cialis comes in lower doses, the smallest of which is just mg. That allows for daily use, ensuring the drug’s always in your system.