Princex contains the active substance – sildenafil, which belongs to the group of drugs from the group of phosphodiesterase type 5 inhibitors. The drug works by supporting the relaxation of blood vessels in the penis, increasing blood flow to the penis during sexual arousal. Princex helps you achieve an erection only if you are sexually aroused. Princex is used to treat erectile dysfunction in adult men, which is impotence defined as the inability to achieve or maintain a penile erection sufficient for sexual intercourse.