Fildena 120 Red Pill works by increasing blood flow to the penis, which helps to achieve and maintain an erection. It contains an active ingredient called sildenafil citrate, which is a type of phosphodiesterase type 5 (PDE5) inhibitor. When a man is sexually stimulated, the PDE5 enzyme breaks down a chemical called cyclic guanosine monophosphate (cGMP), which is responsible for relaxing the smooth muscles in the penis and allowing blood to flow in. Sildenafil citrate inhibits the action of PDE5, allowing cGMP to accumulate and produce a stronger and longer-lasting erection. It is important to note that sexual stimulation is still required for the medication to work.