Cobra 120mg Generic Viagra™ Tablets are a very popular, successful and widely accepted treatment for erectile dysfunction. Patients using Cobra 120mg regularly report successful intercourse and generally continue to use the treatment.nnThe effective treatment time of Cobra 120mg is 4 – 6 hours but many GPs report longer effective times.nnThe active ingredient of Cobra 120mg is Sildenafil Citrate. It belongs to the PDE-5 family of vasodilators. These drugs work by dilating the blood vessels in the body; particularly around the genital area. This in turn, allows stronger blood flow to enable an erection to take place. Cobra 120mg is not an aphrodisiac and stimulation will be required to develop an erection.