ED medications can cause side effects, and it’s crucial to have access to a medical provider if needed. Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. When the blood vessel muscle cells relax, this expands the vessel and increases blood flow; this effect is referred to as vasodilation. For this purpose, one dose works for up to 72 hours. Men with BPH usually have difficulty urinating, a decreased flow of urination, hesitation at the beginning of urination, and a need to get up at night to urinate. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection.Tadalafil increases blood flow to particular areas of the body and is used to treat erectile dysfunction. Learn about side effects, interactions and indications. Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis Drug classes: Agents for pulmonary hypertension, Impotence agents. Generic name: tadalafil [ ta-DAL-a-fil ] Brand names: Adcirca, Cialis Drug class: Impotence agents Medically reviewed by Sanjai Sinha, MD. Last updated on Uses Warnings Before taking Dosage Side effects Interactions FAQ What is Cialis? Cialis (tadalafil) is a moderately priced drug used to treat erection problems in men. It may also be used to treat the enlargement of the prostate gland. This drug is slightly more popular than comparable drugs. It is available in both brand and generic versions.