Impotence/Erectile Dysfunction (cont.)
Impotence/Erectile Dysfunction Treatment: Part 2
- Viagra works best if taken about 1 hour before sexual activity. Only 1 tablet should be taken per day. It should be taken on an empty stomach. Increasing the dosage of Viagra beyond the recommended amounts will not improve the response and will only result in greater side effects.
- The most common side effect of Viagra use is headache, affecting about 16% of users. A drop in blood pressure, transient dizziness, and facial flushing are reported in 10%. Indigestion occurs in 7%, and nasal congestion in 4%.
- Between 3% and 11% of users report some visual problems while on Viagra. This visual disturbance is described as either blurred vision, increased light sensitivity, persistence of a bluish tinge or temporary loss of the ability to distinguish between blue and green.
- None of these side effects is severe and most are described as mild. Very few users stop taking the medication because of side effects.
- Viagra is absolutely not to be taken by men with heart conditions who are taking nitrates such as nitroglycerine or isosorbide (Isordil, Ismo, Imdur). Those with serious heart disease, exertional angina (chest pain), and those taking multiple drugs for high blood pressure are advised to seek the advice of a heart specialist before beginning therapy with sildenafil.
- No nitrate-based drugs should be given to men with suspected heart attacks if they have taken Viagra within 24 hours. Combining Viagra with nitrate-based medications can cause a severe and dramatic drop in blood pressure with potentially very dangerous consequences. This is also why you should absolutely never share your Viagra prescription with anyone else. If they happen to be taking one of the drugs that interacts dangerously with Viagra, the results could be very serious. If there is any question about possible drug interactions, always check with your doctor or pharmacist.
- Certain street drugs such as "poppers" also can cause serious problems if taken with Viagra. Ecstasy is a street drug that may increase sexual desire but interferes with performance. This has prompted some men to combine ecstasy with Viagra. This mixture (a combination sometimes called "sextasy") can improve erection ability but also causes severe headache and priapism. (Priapism is an abnormally prolonged erection that becomes extremely painful and may result in permanent damage to the erection mechanism.) There are also potentially dangerous effects to your heart from mixing Viagra with various other street drugs.
- Several medications can interfere with the chemical processing of Viagra by the liver. These can include ketoconazole (an antifungal medication known by the brand name Nizoral), erythromycin (an antibiotic), and cimetidine (also known as Tagamet, for reducing stomach acid). A lower dose of Viagra should be used if you are taking any of these medications.
- Sildenafil is available in 3 doses: 25 mg, 50 mg, and 100 mg. The starting dose depends on the clinical situation. A man in his 50s with mild sexual dysfunction that is probably related to psychological factors can start on the 25 mg dose. Men with moderate-to-severe ED can begin at the 50 mg dose, and, after testing the effect of the drug on at least 3 occasions, the dose can be modified. Men with severe ED may need to quickly move up to the 100 mg dose. These men are less likely to achieve a satisfactory response, but they should make at least 3-4 attempts with the drug before considering another form of therapy.
- Sildenafil should be taken on an empty stomach about 45-60 minutes prior to sexual intercourse. Stimulation is necessary to produce an erection. An increased ability to achieve good erections can last up to 24 hours but usually only about 4 hours. The drug should not be taken daily.
- Several drugs very similar to Viagra have recently been approved by the FDA. These drugs, called vardenafil (Levitra), tadalafil (Cialis), and avanafil (Stendra). have essentially the same activity and general precautions as Viagra. Cialis has a longer duration of action to develop an erection (up to 24-36 hours) compared with Viagra and Levitra (up to 4 hours) and can be taken daily in a lower dosage if desired.
Medically Reviewed by a Doctor on 6/18/2015
Stephen W Leslie, MD, FACS
Joseph A Salomone III, MD
Francisco Talavera, PharmD, PhD
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