Take sildenafil at around the same times every day. Do not stop taking sildenafil without talking to your doctor. Cialis stays in your system for up to 36 hours and may provide support for erections during that entire time. If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule. What alternatives can I use for erectile dysfunction? Cialis and Viagra are equally effective.Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the . AdSave Time & Money with Online Prescription for Viagra, Cialis, Sildenafil and Tadafil. Free & Private Online Consultant with Real Doctors. Reliable E.D. Meds Shipped Discreetly/5 (3, reviews). AdHeute bestellen, morgen erhalten: Online-Rezept und gratis Lieferung innert 24 Stunden. Unser Online-Ärzteteam verspricht professionelle Beratung und gratis Express-Lieferung/5 (17K reviews)schneller und unkomplizierter gehts nicht – Trusted Shops.