This increased blood flow can cause an erection. Talk with your healthcare provider about your sex life and desired use. If you take nitrates in any form, or are on treatment for pulmonary hypertension , you should not take tadalafil. What special precautions should I follow? John’s wort. Emling S. That means you can have erections whenever you want or need them.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. Cialis ED dosage for occasional use. The normal dosage of Cialis for occasional use in treating ED is 10 mg taken before sexual activity. If you have side effects with the mg dose, your doctor. Note: Some pharmacies do not allow the savings card to be used for opioid drugs. How much does tadalafil or cialis cost near you? Find the best tadalafil or cialis prices near .