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.
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 any health problems 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 up to six hours.
- Vardenafil (Levitra, Staxyn). This medication also is most effective when taken one hour before sex and can be taken with or without food. It's effective for up to seven hours.
- Tadalafil (Cialis). This medication is taken with or without food about one to two hours before sex. It's effective for 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 15 to 30 minutes before sex, depending on the dose. It lasts up to six hours.
Before taking any medication for erectile dysfunction, get your doctor's OK. Medications for erectile dysfunction might not work or might be dangerous if you:
- Take nitrate drugs — commonly prescribed for chest pain (angina) — such as nitroglycerin (Minitran, Nitro-Dur, Nitrostat, others), isosorbide mononitrate (Monoket) and isosorbide dinitrate (Dilatrate-SR, Isordil)
- Have very low blood pressure (hypotension) or uncontrolled high blood pressure (hypertension)
- Have severe liver disease
- Have kidney disease that requires dialysis
Most men who take oral erectile dysfunction medications aren't bothered by side effects. When side effects do occur, they can include:
- Stuffy or runny nose
- Visual changes, such as color tinge to vision, sensitivity to light or blurred vision
- Dizziness and fainting
Rarely, more-serious side effects can occur, including:
- Hearing loss or vision loss. Some men have had sudden loss of hearing or loss of vision after taking one of these medications. However, it isn't clear whether vision or hearing loss was directly caused by taking the medication or by a pre-existing condition. If you're taking an oral erectile dysfunction medication and have sudden loss of hearing or vision, seek prompt medical attention.
- An erection that doesn't go away on its own. Called priapism, this rare condition can be painful and requires medical treatment to avoid damage to your penis. If you have an erection that lasts more than four hours, seek immediate medical attention.
Treatments for erectile dysfunction are big business, and online scams abound. If you do buy medications over the Internet:
- Check to see if an online pharmacy is legitimate. Never order medications from an online pharmacy if there's no way to contact the pharmacy by phone, if prices seem too good to be true or if you're told no prescription is necessary. Some illegal businesses sell counterfeit versions of legitimate medications, which can be ineffective or dangerous. In the U.S., the National Association of Boards of Pharmacy can tell you whether an online pharmacy is licensed and in good standing.
- Make sure you get the right prescription and dose. When you order medications — and when you receive them in the mail — make sure they're the exact dose and type prescribed by your doctor.
- Don't be fooled into buying 'herbal viagra.' Never take any medications that claim to be the "herbal" or nonprescription equivalent of an oral medication for erectile dysfunction. These aren't an effective alternative, and some contain harmful substances.
June 06, 2015
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- Stendra (prescribing information). Mountain View, Calif.: Vivus, Inc.; 2015. https://www.stendra.com/. Accessed May 18, 2015.