Cialis is a prescription medication used to treat erectile dysfunction (ED) and symptoms of benign prostatic hyperplasia (BPH). Its active ingredient, tadalafil, helps increase blood flow to the penis, allowing for an erection when combined with sexual stimulation. Cialis can be taken as needed or daily, depending on the prescribed dosage. It typically starts working within 30 minutes and can last up to 36 hours, making it a popular choice for many men. As with any medication, it is important to consult a healthcare provider for proper guidance and to discuss potential side effects.