Which Works Faster? Some studies show that Cialis reaches its maximum effect around two hours after taking an as-needed dose. This medicine works best when you take it on an empty stomach an hour before sex. Lemonaid can prescribe sildenafil generic Viagra , tadalafil generic Cialis , and vardenafil generic Levitra. In trials of the drug, individuals taking Cialis saw a significant reduction in the frequency and urgency of urination and improved urine flow.Tadalafil (Cialis) is taken by mouth either as needed before sexual activity or once daily for erectile dysfunction (ED).It’s also taken once daily to treat symptoms from an enlarged prostate (benign prostatic hyperplasia, or BPH).Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include . Patients should not use CIALIS if sex is inadvisable due to cardiovascular status ().Use of CIALIS with alpha-blockers, antihypertensives or substantial amounts of alcohol (≥5 units) may lead to hypotension (, ).CIALIS is not recommended in combination with alpha-blockers for the treatment of BPH because efficacy of the . Summary. Cialis and Viagra are both pills for treating erectile dysfunction. They are PDE5 inhibitors that allow for increased blood flow to the penis, .