Without physical action to the penis, such as that occurring during sexual intercourse, tadalafil will not work to cause an erection. Physicians should discuss with patients the appropriate action in the event that they experience anginal chest pain requiring nitroglycerin following intake of CIALIS. Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry. Tadalafil may cause side effects. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco. Some studies show that Cialis reaches its maximum effect around two hours after taking an as-needed dose. · Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Check with your doctor immediately if any of the following side effects occur: Less common. Arm, back, or jaw pain. blurred vision.  · Tadalafil works on the PDE5 enzyme in the lungs to relax the blood vessels. This will increase the supply of blood to the lungs and reduce the workload of the heart. . If you have a private prescription for tadalafil, read the information that comes with your medicine carefully. The strength and dosage instructions can vary. Dosage and strength. Tadalafil comes as mg, 5mg, 10mg and 20mg tablets. Dose for erectile dysfunction. The usual dose of tadalafil for erectile dysfunction is 10mg when you need it.