Cialis reaches its maximum effectiveness two hours after you take it. A few more candles, a little less champagne — and who knows what could happen… FAQs Is it safe to take Viagra? This is a type of high blood pressure that occurs between the heart and the lungs. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. You should not use erectile dysfunction medicate recreationally, or if you have not been diagnosed with erectile dysfunction. In fact, Viagra only works to give you an erection when you are both aroused and stimulated, and even then it may take up to an hour of stimulation with Viagra to achieve an erection strong enough for penetration. This helps you achieve a firmer and longer-lasting erection.Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil . The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 . Viagra doesn’t work on its own. You’ll still need to feel sexually aroused to get an erection. Feeling relaxed and comfortable can also help Viagra take effect sooner. The average .