Both Cialis and Viagra work quickly. However, if you take sildenafil with a high-fat meal, it will take longer for the medication to start to work. Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking sildenafil. In many of the studies, of both fixed dose and titration designs, daily diaries were kept by patients. John’s wort. Take sildenafil as needed before sexual activity. Viagra had no effect on saquinavir pharmacokinetics.VIAGRA may not be right for every man, but it has been shown to help approximately 4 out of 5 men get and keep erections hard enough for sex at doses of 50 mg or mg.* * Seventy-two percent, 80%, and 85% of the patients on 25 mg, 50 mg, and mg of VIAGRA, respectively, achieved erections hard enough for sex, compared to 50% on .  · For example, a year-old might start at a dose of 50 milligrams (mg), while a year-old might have a starting dose of 25 mg. This is because, in older people, the body clears Viagra from your. Although erectile dysfunction (ED) may be an upsetting diagnosis for some, many people find their condition is treatable with Viagra — sometimes called the “little blue pill” — and .