Some may find that Cialis works in two hours and takes the medicine two hours before sexual activity. Talk to your doctor about which dosing schedule is right for you. Dosing is as follows: As needed for ED: 5 to 20 mg by mouth as a one-time dose, with a maximum of one dose in 24 hours. Your doctor will probably tell you not to take tadalafil if you are taking nitrates. Comparison with actions of other PDE5 inhibitors[ edit ] Sildenafil and vardenafil inhibit PDE6, an enzyme found in the eye, more than tadalafil. What special precautions should I follow?Generic tadalafil pills are often less than half the price of Cialis. A study found that from to , the median price of Cialis jumped from $ to $ for 30 tablets. Generic brands. Some common side effects of tadalafil include headache, indigestion, and back pain. Generic tadalafil became available in and it’s the more affordable alternative to brand Cialis. By using a coupon from RxSaver, you can save up to 80% off the cash price of Adcirca or Alyq, even if you don’t have insurance. Note: Some pharmacies do not allow the savings card to be used for opioid drugs. How much does tadalafil or cialis cost near you? Find the best tadalafil or cialis prices near you now with our cost comparison tool and start saving today.