Take all of the tablets for your daily dose at one time each day; do not divide the tablets to take as separate doses. In , the Phase 2 clinical studies were initiated for males experiencing ED, then progressed to the Phase 3 trials that supported the drug’s FDA approval. Tadalafil was found to have similar benefits for lower urinary tract symptoms as the usually prescribed tamsulosin. Before taking tadalafil, tell your doctor and pharmacist if you are allergic to tadalafil, any other medications, or any of the ingredients in tadalafil tablets. Ask your pharmacist for a list of the ingredients. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Prolonged erections can be dangerous.tadalafil Used for Benign Prostatic Hyperplasia, Erectile Dysfunction erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available .  · 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 lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash.