In some cases, ED can cause a strain on relationships and impact self-esteem. This is important for your overall health and safety, as certain medications can negatively interact with each other or cause existing conditions to worsen. These PDE5 inhibitors may cause headache, flushing, drop in blood pressure, or other adverse effects. Yes, ED pills can cause side effects. Privacy: Confirm that your personal data and payment details are confidential. Medical consultations were also taken into consideration, as PDE5 inhibitors require a valid prescription from a licensed medical provider.Sildenafil (Viagra) is a phosphodiesterase-5 (PDE-5) inhibitor. PDE-5 is a protein in your body that breaks down the molecules that normally cause an erection. When it blocks PDE-5, sildenafil (Viagra) helps an erection occur by allowing certain muscles in the penis to relax and the penis to fill with blood.  · Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat . Viagra is absorbed quickly into your body. It can start working within 30 minutes, but it may take a couple hours for some people. However, one study on Viagra found that about 70% of men achieved erections in 30 minutes, and more than 80% of men achieved erections within 45 minutes. For most men, the effects of Viagra will start within .