Filagra helps men get and keep an erection by relaxing the penis' muscles and boosting blood flow to them. A PDE5 inhibitor called sildenafil citrate aids in the relaxation of penile muscles, which increases blood flow in the area and results in an erection. Your doctor may also prescribe this medication to address other illnesses. Pay close attention to the instructions on your prescription label, and ask your pharmacist or doctor to clarify any parts you don't understand. It should be stored away from heat, light, and moisture at room temperature, which is between 15 and 30 degrees Celsius.