Penegra 100 mg is a great prescription medication used to treat erectile dysfunction (ED) in men. Penegra 100 mg contains the active ingredient sildenafil citrate (100 mg). Penegra 100 mg is an excellent choice of medication for the treatment of ED as its issues can be quickly resolved. The medicine relaxes the muscles by increasing blood flow to enter the penis, providing harder erections to allow for pleasurable sensual activity.