SIDALIST (TADALAFIL & SILDENAFIL) In India they had the creative idea to combine Sildenafil with the Cialis generic substitute TADALAFIL, which has extra properties not in Sildenafil. Also TADALFIL remains in the bloodstream much longer. Sildenafil is the most widely used and until recently most popular Viagra generic substitute for erectile dysfunction. Both increase blood flow. Do not use when drinking alcohol.