Your doctor will determine which Sildenafil the best way for you to take tadalafil. The first way is to take it as needed, usually at least 30 minutes before sexual activity. The second way to treat ED is to take tadalafil regularly, once a day every day. If you take it this way, you may attempt sexual activity at any time between your doses. If you are taking tadalafil to treat both ED and BPH, take it as directed by your doctor, usually once a day. You may attempt sexual activity at any time between your doses. If you are taking tadalafil once daily for BPH, or for ED, or for both, problems with erection it regularly to get the most benefit from it. To help you remember, take it at the same time each day. Headache, stomach upset, Sildenafil Citrate, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.