Cialis works by enhancing the effects of one of the chemicals the body normally releases into the penis during sexual arousal. This medicine is available only with your doctor’s prescription. Alternatively, Cialis may be prescribed as an as-needed treatment for ED, to be taken before sexual activity. For this purpose, one dose works for up to 72 hours. Tadalafil was found to have similar benefits for lower urinary tract symptoms as the usually prescribed tamsulosin.The formulas of the main anabolics are very similar in structure to natural steroid hormones, and, accordingly, they are recognized by the pituitary and hypothalamus. And since the regulator believes that there is an overabundance of them in the body, it gives the command to turn off the production of its own hormones. Side Effects. Headache, stomach upset, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To. How Cialis Works. Tadalafil and other PDE5 inhibitors primarily work by inducing muscle relaxation. Tadalafil stops the breakdown of a chemical responsible for relaxing muscles. In ED and PAH, the drug targets muscle cells in blood vessels. When the blood vessel muscle cells relax, this expands the vessel and increases blood flow; this .