Persons surnamed “Cialis” objected to Eli Lilly and Company’s so naming the drug, but the company has maintained that the drug’s trade name is unrelated to the surname. Tell your doctor right away if you become pregnant. If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department. Furthermore, the longer half-life is the basis for tadalafil’s daily therapeutic use in treating pulmonary arterial hypertension. When taking Adcirca or Alyq, you may need 2 tablets for a full dose. Do not split the dose. You could be having a life-threatening side effect. · flushing (warmth, redness, or tingly feeling); nausea, upset stomach; runny or stuffy nose; or. muscle pain, back pain, pain in your arms, legs, or back. This is not a complete list of side. Tadalafil (Cialis) is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). Tadalafil works by helping to relax the blood vessels in the penis, allowing blood to flow into the penis, and causing an erection.  · But on average, its effects start to lessen 2 to 3 hours after you take a dose. The typical dose for once-daily Cialis for ED is milligrams (mg) to 5 mg. When used as needed for ED, the usual.