This is important for your overall health and safety, as certain medications can negatively interact with each other or cause existing conditions to worsen. It’s available in 50 mg, mg, and mg tablets. If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. Stendra avanafil : This is an as-needed medication taken 30 minutes before sex and can last up to six hours. How should this medicine be used? What alternatives can I use for erectile dysfunction?Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men. Side Effects. Headache, stomach upset, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To. Cialis and generic tadalafil are available in four different strengths— mg, 5 mg, 10 mg and 20 mg—but which one should you take? The 20 mg tablet is the .