Mutagenesis Sildenafil was negative in in vitro bacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitro human lymphocytes and in vivo mouse micronucleus assays to detect clastogenicity. It can be dangerous to take sildenafil if you also take medicines called nitrates often given for chest pain. Taking sildenafil alone will not cause an erection. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. In a study of healthy male volunteers, sildenafil mg did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.FAQs What to consider Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. . Can I buy generic Viagra over the counter or do I need a prescription? In the U.S. and most other countries, generic Viagra is only available with a prescription. AdBrowse & discover thousands of brands. Read customer reviews & find best sellers. Free shipping on qualified orders. Free, easy returns on millions of test1.ru has been visited by 1M+ users in the past monthPopular Links: Pharmacy · Media · Accessibility · Security.