Counterfeit medicines can be very dangerous. This increased blood flow can cause an erection. Nitrates come as tablets, sublingual under the tongue tablets, sprays, patches, pastes, and ointments. Tadalafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. However, because sexual stimulation is required to initiate the local penile release of nitric oxide, tadalafil’s inhibition of PDE5 will have no effect without sexual stimulation. Also tell your doctor if you have or have ever had pulmonary veno-occlusive disease PVOD; blockage of veins in the lungs ; any condition that affects the shape of the penis; diabetes; high cholesterol; high or low blood pressure; irregular heartbeat; a heart attack or heart failure; angina chest pain ; a stroke; ulcers in the stomach; a bleeding disorder; blood circulation problems; blood cell problems such as sickle cell anemia a disease of the red blood cells , multiple myeloma cancer of the plasma cells , or leukemia cancer of the white blood cells ; or heart, kidney, or liver disease. If you are taking tadalafil to treat PAH or BPH, follow your doctor’s directions and the guidelines in this paragraph. · Get answers to common questions about the dosage of Cialis. What form does Cialis come in? Cialis comes as a tablet that you take by mouth. Available strengths of Cialis ( mg, 5 mg, 10 mg, 20 mg). Cialis and Viagra have both been shown to be safe and effective for erectile dysfunction. The main differences are cost and timing. For occasional use, most people start with Viagra which also tends to be cheaper. Cialis lasts longer and can also be taken daily at a . tadalafil Used for Benign Prostatic Hyperplasia, Erectile Dysfunction erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available .