Erectile dysfunction: Viagra and other oral medications

By Mayo Clinic Staff

Oral medications are often the first line of treatment for erectile dysfunction. For most men who have trouble keeping an erection firm enough for sex (erectile dysfunction), these medications work well and cause few side effects.

Sildenafil (Viagra), vardenafil (Levitra, Staxyn), tadalafil (Cialis) and avanafil (Stendra) are oral medications that reverse erectile dysfunction by enhancing the effects of nitric oxide, a natural chemical your body produces that relaxes muscles in the penis. This increases blood flow and allows you to get an erection in response to sexual stimulation.

How oral medications differ

Although they work in similar ways, each oral medication has a slightly different chemical makeup. These minor differences affect the way each medication works, such as how quickly it takes effect and wears off, and the potential side effects. Your doctor will consider these factors as well as other conditions you have and possible interactions with other medications you take.

  • Sildenafil (Viagra). This medication is most effective when taken on an empty stomach one hour before sex. It's effective for four to five hours or more if you have mild to moderate erectile dysfunction.
  • Vardenafil (Levitra, Staxyn). This medication also is most effective when taken one hour before sex and can be taken with or without food. A high-fat meal might keep it from absorbing as quickly.

    Vardenafil is effective for four to five hours or more if you have mild to moderate erectile dysfunction. A newer form of the drug that dissolves on the tongue might work faster than the pill that you swallow.

  • Tadalafil (Cialis). This medication is taken with or without food about one to two hours before sex. It's effective for up to 36 hours. It can be taken in a small dose daily or in a larger dose as needed.
  • Avanafil (Stendra). This medication is taken with or without food 30 minutes before sex, depending on the dose. It lasts up to six hours.

Because these drugs are similarly effective, the American College of Physicians recommends that the choice be based on your preferences, including cost, ease of use, how long the drug's effects last and side effects. There are generic versions of sildenafil, verdenafil and tadalafil available.

When oral medications might not be safe

Before taking any medication for erectile dysfunction, get your doctor's OK. Medications for erectile dys