According to Harvard Medical School, male impotence is now referred to as erectile dysfunction. The inability to get and maintain an erection is not necessarily a cause for concern unless it is an ongoing problem. Harvard Medical School calls it a "second sexual revolution," referring to the new medications available for erectile dysfunction. Although the three most common drugs increase nitric oxide to relax blood vessels and increase blood flow, they all have minor differences.
Viagra
Sildenafil, or Viagra, is also marketed as Revatio. Revatio is used to treat pulmonary arterial hypertension and to increase exercise ability in male and female athletes. Viagra is taken no more than once a day without food and should not be taken in conjunction with nitrates. Nitrates are used for heart problems including chest pain. Drugs.com explains to take a pill 60 minutes to four hours prior to sexual activity. An erection will occur upon stimulation. Viagra does not need to be taken daily to be effective, only before anticipated sexual activity.
Cialis
Also marketed under the name Adcirca for pulmonary hypertension, and known genericaly as tadalafil, Cialis can be taken with or without food, no more than once a day. Unlike its counterparts, Cialis can be taken up to 36 hours prior to anticipated sexual activity. It is not to be taken if nitrates are used. Drugs.com advises a period of 24 hours between doses.
Levitra
Levitra's generic name is vardenafil. As with Cialis and Viagra, it is not to be used with nitrates and common to the others, if an erection lasting longer than four hours, known as priapism, occurs, it requires medical attention. Levitra is to be taken without food and dosage can be up to 30 minutes before sexual activity.
