Viagra

What does Viagra do?

Viagra (sildenafil) is a drug used to treat erectile dysfunction (commonly called ED or "impotence") in men. This means they either can't have erections or can't maintain them.

On the market since the late 1990s, Viagra is slated to be available in generic form in December 2017. In 2012, the market for Viagra was valued at about $4.3 billion worldwide, but the overall market for erectile dysfunction drugs in general is falling because of expiring patents.

It's important to understand that Viagra and other ED drugs (such as Cialis or Levitra ) aren't aphrodisiacs. If a man isn't interested in sex or doesn't feel aroused, these medications won't give him an erection. But if a man has trouble getting an erection despite no shortage of desire, Viagra and similar drugs can help get the blood flowing to the right places.

Doctors also prescribe sildenafil to both men and women to treat the symptoms of pulmonary arterial hypertension, a type of high blood pressure that affects the heart and lungs.

How effective is it?

Viagra has very high rates of effectiveness for ED, depending on the dose you take. Most people take a 50 milligram pill.

In a 2015 review of about 150 research studies, the 50 mg dose worked about 50 percent better than a placebo and worked better than other ED drugs. Earlier studies indicated that Viagra worked for about 70 to 85 percent of men with erectile dysfunction caused by physical factors, such as damaged nerves (a frequent effect of diabetes), narrowed blood vessels (an effect of atherosclerosis), or side effects from medications. It can also help men whose erectile dysfunction stems from anxiety or other psychological causes.

How do I take it?

You usually swallow one tablet about an hour before sex. It takes an hour to take peak effect, though the waiting time can range from half an hour to two hours. The process doesn't begin automatically, though -- you still need to be aroused in order to have an erection. Viagra starts clearing out of the bloodstream about two hours after you take it, and it's mostly gone after six hours or so.

How does Viagra work?

When a man becomes aroused, certain muscles in the penis relax, opening up a flow of blood to the penis. In simple terms, Viagra works by promoting a substance that helps those muscles relax.

Does it have any side effects?

The most serious side effect of Viagra results from a possible drug interaction. Taking Viagra while you're on any drug that contains nitrates, such as a common type of heart medication called nitroglycerin (the same chemical as the active ingredient in dynamite, sold under many brand names including Nitrostat, Transderm-Nitro, and Nitrolingual), can cause a sharp and sometimes dangerous drop in blood pressure. Talk to your doctor or pharmacist to make sure Viagra won't interact in a harmful way with anything else you're taking.

Even if you're not on nitroglycerin, Viagra's new label advises doctors to use caution in prescribing the drug to anyone with a history of cardiovascular disease, including heart attack, stroke, angina, or high or low blood pressure. That's because if you should ever suddenly need to take nitroglycerin, the chance of an interaction with Viagra could be too great to risk. To date, at least 130 men have died shortly after taking Viagra. In most cases they had heart attacks, although it isn't clear whether those were caused by Viagra or by the excitement and exertion of having sex after a long break.

Other side effects are related to the way Viagra works in the body. The enzyme blocked by Viagra, PDE5, is also found in other parts of the body, among them the blood component known as platelets and some muscles around blood vessels. The drug can disrupt the way blood cells and vessels normally function in certain areas, including the head, skin, and stomach -- which might explain many of its commonly reported side effects, such as headache (reported by 16 percent of users), flushed skin (10 percent), and indigestion (7 percent).

Viagra blocks PDE5 very well, but it can also partly block a closely related enzyme, PDE6, which is found in the retina of the eye. That's why about 3 percent of men on Viagra experience visual side effects, including bluish or blurry vision and sensitivity to light. More than a decade ago, the FDA issued an alert that a small number of men lost eyesight in one eye some time after taking Viagra, Cialis, or Levitra. Doctors don't know whether the drugs caused the vision loss, but people with certain conditions -- like heart disease, diabetes, hypertension -- are at higher risk of developing the complication. Similarly, men with existing eye conditions -- like retinitis pigmentosa, for example -- may need to steer clear of the drug altogether to avoid eye damage.

Viagra, Cialis, and Levitra may also cause sudden hearing loss. While hearing loss is a common malady among older people, and the FDA found only 29 cases of sudden hearing loss related to these drugs, the agency emphasizes that "sudden hearing loss is an uncommon event at any age."

Finally, in a few cases, in healthy men Viagra has caused a painful, abnormally long-lasting erection (a condition called priapism) that may lead to erectile dysfunction if it isn't treated quickly.

If you are pregnant or breastfeeding or smoke, talk to your doctor. Your doctor should also know if you have kidney or liver disease, a pulmonary disease, diabetes, bleeding problems, leukemia, multiple myeloma, sickle cell anemia, a stomach ulcer, or eye problems.

You should also inform your doctor if you have angina or chest pain during sex, heart disease, heart rhythm problems, high or low blood pressure, or a history of heart attack or stroke.

Can Viagra help women too?

So far there's no evidence that it can help women who have sexual problems. A small study of postmenopausal women on Viagra found that the drug did increase blood flow to the clitoris (often uncomfortably so) but didn't help any of the women get aroused more easily or feel more pleasure during sex.

How do I get Viagra?

If you think you need the little blue pills, you probably have a health problem already -- so it's important to discuss things with your doctor in order to make sure Viagra can actually help you without harming you. The drug is approved for sale in the US, Japan, and Europe, and is legally available by prescription only.

Some websites sell Viagra illegally without a prescription, but it's NOT a good idea to order from them. There's no guarantee that you'll get the genuine article, you'll pay much more, and your medical history won't be reviewed properly, if at all.

Are there any effective alternatives?

Viagra isn't the first -- or the only -- game in town. Two additional drugs that work much like Viagra have been approved by the FDA: Levitra (vardenafil) and Cialis (tadalafil). Until these pills came along, the most common drug treatment for erectile dysfunction consisted of injecting alprostadil (a synthetic form of a naturally-occurring chemical called prostaglandin E1) into the penis. For obvious reasons, that never caught on the way Viagra has. Prostaglandin E1 works much like Viagra, relaxing muscles and dilating blood vessels.

Another prescription medication, Regitine (its generic name is phentolamine) is also an erectile dysfunction drug that's injected into the penis. A pill form called Vasomax is still undergoing FDA review. Although it's less effective than injections, phentolamine enhances the flow of blood to the penis to produce an erection. But unlike Viagra, it doesn't interfere with nitrate medicines and could be safer for men with heart disease.

Some herbal preparations, often containing yohimbe, are sold under names like "Viegra" and "Viagre," but these are not related to the real Viagra. Yohimbe is the bark of an African tree, fabled as a sexual stimulant in men and women. Like Viagra, the bark's active ingredient (called yohimbine) increases blood flow to the penis, but it hasn't shown consistent results in clinical studies of erectile dysfunction. In addition, yohimbe can cause dangerous side effects, including too-rapid or irregular heartbeat, low or high blood pressure, kidney failure, seizures and heart attack. It's important to know the American Urologic Association does not recommend yohimbine for the treatment of erectile dysfunction.

References

Chen L, et al. Phosphodiesterase 5 Inhibitors for the Treatment of Erectile Dysfunction: A Trade-off Network Meta-analysis. Europen Urology. October 2015. Volume 68, Issue 4, Pages 674680 http://www.europeanurology.com/article/S0302-2838(15)00250-X/abstract/phosphodiesterase-5-inhibitors-for-the-treatment-of-erectile-dysfunction-a-trade-off-network-meta-analysis

Transparency Market Research. Erectile Dysfunction Drugs Market is expected to reach an estimated value of US$3.4 billion in 2019. https://globenewswire.com/news-release/2015/04/16/725113/10129251/en/Erectile-Dysfunction-Drugs-Market-is-expected-to-reach-an-estimated-value-of-US-3-4-billion-in-2019-Transparency-Market-Research.html

PubMed Health. Sildenafil (By mouth) https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0012114/?report=details

Mayo Clinic. Sildenafil. 2010. http://www.mayoclinic.com/health/drug-information/DR601513 U.S. National Library of Medicine. SIldenafil. 2008. http://www.nlm.nih.gov/medlineplus/druginfo/meds/a699015.html US Food and Drug Administration. Questions and Answers about Viagra, Levitra, Cialis, and Revatio: Possible sudden Hearing Loss. October 2007. http://www.fda.gov/cder/drug/infopage/ed_drugs/QA.htm Montague DK et al. The Management of Erectile Dysfunction: An Update. American Urologic Association Education and Research. May 2006.

What does Viagra do?

As you've no doubt gathered from the TV commercials, Viagra (sildenafil) is a drug used to treat erectile dysfunction (commonly called ED or "impotence") in men who either can't have or can't maintain erections. On the market since March 1998, it is now available in generic form. It is one of the most commercially successful drugs ever launched, with millions of prescriptions filled at a cost of more than $ 1 billion during the first year alone. It even has the blessing of the Vatican, on the ground that it can strengthen families.

It's important to understand that Viagra and other ED drugs (such as Cialis or Levitra ) aren't aphrodisiacs. If a man isn't interested in sex or doesn't feel aroused, these medications won't give him an erection. But if a man has trouble getting an erection despite no shortage of desire, Viagra and similar drugs can help get the blood flowing to the right places.

How effective is it?

Viagra works for about 70 to 85 percent of men with erectile dysfunction caused by physical factors, such as damaged nerves (a frequent effect of diabetes), narrowed blood vessels (an effect of atherosclerosis), or side effects from medications. It can also help men whose erectile dysfunction stems from anxiety or other psychological causes.

How do I take it?

You usually swallow one tablet about an hour before sex. It takes an hour to take peak effect, though the waiting time can range from half an hour to two hours. The process doesn't begin automatically, though -- you still need to be aroused in order to have an erection. Viagra starts clearing out of the bloodstream about two hours after you take it, and it's mostly gone after six hours or so.

How does Viagra work?

When a man becomes aroused, certain muscles in the penis relax, opening up a flow of blood to the penis. In simple terms, Viagra works by promoting a substance that helps those muscles relax.

Does it have any side effects?

The most serious side effect of Viagra results from a possible drug interaction. Taking Viagra while you're on any drug that contains nitrates, such as a common type of heart medication called nitroglycerin (the same chemical as dynamite, sold under many brand names including Nitrostat, Transderm-Nitro, and Nitrolingual), can cause a sharp and sometimes dangerous drop in blood pressure. Talk to your doctor or pharmacist to make sure Viagra won't interact harmfully with anything else you're taking.

Even if you're not on nitroglycerin, Viagra's new label advises doctors to use caution in prescribing the drug to anyone with a history of cardiovascular disease, including heart attack, stroke, angina, or high or low blood pressure. That's because if you should ever suddenly need to take nitroglycerin, the chance of an interaction with Viagra could be too great to risk. To date, at least 130 men have died shortly after taking Viagra. In most cases they had heart attacks, although it isn't clear whether those were caused by Viagra or by the excitement and exertion of having sex after a long break.

Other side effects are related to the way Viagra works in the body. The enzyme blocked by Viagra, PDE5, is also found in other parts of the body, among them the blood component known as platelets and some muscles around blood vessels. The drug can disrupt the way blood cells and vessels normally function in certain areas, including the head, skin, and stomach -- which might explain many of its commonly reported side effects, such as headache (reported by 16 percent of users), flushed skin (10 percent), and indigestion (7 percent).

Viagra blocks PDE5 very well, but it can also partly block a closely related enzyme, PDE6, which is found in the retina of the eye. That's why about 3 percent of men on Viagra experience visual side effects, including bluish or blurry vision and sensitivity to light. In July 2005, the FDA issued an alert that a small number of men lost eyesight in one eye some time after taking Viagra, Cialis, or Levitra. Doctors don't know whether the drugs caused the vision loss, but people with certain conditions -- like heart disease, diabetes, hypertension -- are at higher risk of developing the complication. Similarly, men with existing eye conditions -- like retinitis pigmentosa, for example -- may need to steer clear of the drug altogether to avoid eye damage.

Most recently, the FDA reported that Viagra, Cialis, and Levitra may also cause sudden hearing loss. While hearing loss is a common malady among older people, and the FDA found only 29 cases of sudden hearing loss related to these drugs, the agency emphasizes that "sudden hearing loss is an uncommon event at any age."

Finally, in a few cases, in healthy men Viagra has caused a painful, abnormally long-lasting erection (a condition called priapism) that may lead to erectile dysfunction if it isn't treated quickly.

Can Viagra help women too?

So far there's no evidence that it can help women who have sexual problems. A small study of postmenopausal women on Viagra found that the drug did increase blood flow to the clitoris (often uncomfortably so) but didn't help any of the women get aroused more easily or feel more pleasure during sex.

How do I get Viagra?

If you think you need the little blue pills, you probably have a health problem already -- so it's important to discuss things with your doctor in order to make sure Viagra can actually help you without harming you. The drug is approved for sale in the US, Japan, and Europe, and is legally available by prescription only.

Some Web sites sell Viagra illegally without a prescription, but it's NOT a good idea to order from them. There's no guarantee that you'll get the genuine article, you'll pay much more, and your medical history won't be reviewed properly, if at all.

Are there any effective alternatives?

Viagra isn't the first -- or the only -- game in town. Two additional drugs that work much like Viagra have been approved by the FDA: Levitra (vardenafil) and Cialis (tadalafil). Until these pills came along, the most common drug treatment for erectile dysfunction consisted of injecting alprostadil (a synthetic form of a naturally-occurring chemical called prostaglandin E1) into the penis. For obvious reasons, that never caught on the way Viagra has. Prostaglandin E1 works much like Viagra, relaxing muscles and dilating blood vessels.

Another prescription medication, Regitine (it's generic name is phentolamine) is also an erectile dysfunction drug that's injected into the penis. A pill form called Vasomax will soon be available, although it's less effective than injections. Just as Viagra does, phentolamine enhances the flow of blood to the penis to produce an erection, but unlike Viagra, it doesn't interfere with nitrate medicines and could be safer for men with heart disease.

Some herbal preparations, often containing yohimbe, are sold under names like "Viegra" and "Viagre," but these are not related to the real Viagra. Yohimbe is the bark of an African tree, fabled as a sexual stimulant in men and women. Like Viagra, the bark's active ingredient (called yohimbine) increases blood flow to the penis, but it hasn't shown consistent results in clinical studies of erectile dysfunction. Yohimbine is also available in prescription pill form, under the name Yocon. This purified form of yohimbine has fewer side effects than the raw bark, which can dangerously increase blood pressure and heart rate. However, it's important to note that the American Urologic Association does not recommend yohimbine for the treatment of erectile dysfunction.

References

Mayo Clinic. Sildenafil. 2010. http://www.mayoclinic.com/health/drug-information/DR601513

U.S. National Library of Medicine. SIldenafil. 2008. http://www.nlm.nih.gov/medlineplus/druginfo/meds/a699015.html

US Food and Drug Administration. Questions and Answers about Viagra, Levitra, Cialis, and Revatio: Possible sudden Hearing Loss. October 2007. http://www.fda.gov/cder/drug/infopage/ed_drugs/QA.htm

Montague DK et al. The Management of Erectile Dysfunction: An Update. American Urologic Association Education and Research. May 2006.

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