 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  about how long you should continue taking this medication. To treat erectile dysfunction-ED, there are 2 ways that tadalafil may be prescribed. Your doctor will determine which is the best way for you to take tadalafil. Follow your doctor's directions exactly since your dosage depends on how you are taking it. The first way is to take it as needed, usually at least 30 minutes before sexual activity. Tadalafil's effect on sexual ability may last up to 36 hours. 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, take it regularly to get the most benefit from it. To help you remember, take it at the same time each day. Tell your doctor if your condition does not improve or if it worsens.The side effects of Tadalafil Oral: Head </s>