If you have certain health conditions or are taking certain medications, your doctor may tell you to take tadalafil less often or may prescribe a lower dose to be taken once a day. What special dietary instructions should I follow? References Cialis vs. Read more: Levitra — The other ED drug Although Viagra and Cialis are both practical, Cialis may be preferred for its once-daily dosage, as it gives you more freedom to be spontaneous in your sex life. In the picture below, you can see some of the commonly shared side effects of Cialis and side effects of Viagra : Cialis and Viagra side effects If you are taking Viagra or Cialis and you experience nausea, chest pain, or dizziness during sex, seek immediate medical help as you may have a life-threatening condition. It also alleviates the symptoms of benign prostatic hyperplasia i.CIALIS for Use as Needed. Creatinine clearance 30 to 50 mL/min: A starting dose of 5 mg not more than once per day is recommended, and the maximum dose is 10 mg not more than once in every 48 hours. Creatinine clearance less than 30 mL/min or on hemodialysis: The maximum dose is 5 mg not more than once in every 72 hours [see . Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men. Cialis may cause limb pain, while Viagra is not expected to have this side effect. Both Cialis (tadalafil) and Viagra (sildenafil) are phosphodiesterase-5 (PDE5) inhibitors used to treat impotence (erectile dysfunction, or ED). Cialis is also used to treat enlarged prostate. One is not better than the other in general, but individual patients.