If you have erection problems, tadalafil works by temporarily increasing blood flow to the penis when you get sexually excited. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. What should I talk to my doctor about when considering if Cialis is right for me? If you are taking tadalafil for erectile dysfunction, your doctor will probably start you on an average dose of tadalafil and increase or decrease your dose depending on your response to the medication. Take all of the tablets for your daily dose at one time each day; do not divide the tablets to take as separate doses. You can only get it on prescription for erectile dysfunction if you have a specific condition such as multiple sclerosis or a spinal cord injury.Tadalafil and Cost: How to Lower Long-Term Costs and More. Find information on tadalafil and cost, how generic and brand-name prices compare, what financial assistance is available, and more. Take tadalafil (Cialis) as prescribed by your provider. If you’re taking tadalafil (Cialis) as-needed for ED, you should take no more than one dose per day. The effects of tadalafil (Cialis) should last for up to 36 hours after a dose. Taking this medication more often can raise your risk for serious side effects, such as priapism or vision. Tadalafil Brand names: Cialis, Adcirca. Tadalafil. Find out how tadalafil treats erectile dysfunction, pulmonary hypertension and benign prostate enlargement, and how to take it.