Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. In addition, ED is extremely common. Especially tell your healthcare provider if you take any of the following: medicines called nitrates medicines called guanylate cyclase stimulators such as Adempas riociguat medicines called alpha-blockers, such as Hytrin terazosin HCl , Flomax tamsulosin HCl , Cardura doxazosin mesylate , Minipress prazosin HCl , Uroxatral alfuzosin HCl , Jalyn dutasteride and tamsulosin HCl , or Rapaflo silodosin. Both Cialis and Viagra are effective at these doses. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. If you have an erection that lasts more than 4 hours, get medical help right away. However, the dosage can range from 25— mg.Cialis and Viagra have both been shown to be safe and effective for erectile dysfunction. The main differences are cost and timing. For occasional use, most people start with Viagra which also tends to be cheaper. Cialis lasts longer and can also be . AdTake Charge of Your Sexual Health with Our Top-Rated Male Enhancement Products! Reviews and Comparisons Of The Best Male Enhancement Products. See Which Products test1.ru has been visited by 10K+ users in the past monthHonest & Unbiased Reviews · Over 20 Years Online · Over Products Tested. Side Effects. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may.