Grapefruit and grapefruit juice may change the amount of this medicine that is absorbed in the body. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. Children—Use and dose must be determined by your doctor. Angina severe chest pain or Arrhythmia irregular heartbeat , uncontrolled or Heart attack within the last 3 months or Heart failure within the last 6 months or Hypertension high blood pressure , uncontrolled or Hypotension low blood pressure or Retinal disorders eye problem or Retinitis pigmentosa an inherited eye disorder or Stroke, recent history of—Should not be used in patients with these conditions. This medicine comes with a patient information leaflet.tadalafil. erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include headache and indigestion. Tadalafil (Cialis) does interact with some medications. Cialis and generic tadalafil are available in four different strengths— mg, 5 mg, 10 mg and 20 mg—but which one should you take? If you’ve never tried Cialis before, your doctor will likely start you on a low dose, like mg or 5 mg. The 20 mg tablet is the highest strength and is often not preferred because it has the potential to. Generic version: tadalafil; Read on to learn about Cialis and cost, as well as how to save money on prescriptions and find the best price. ( mg, 5 mg, 10 mg)? Cialis comes in several.