Viagra works by relaxing the muscles in the walls of blood vessels in certain areas of the body. In most cases, Viagra works well and has changed people's lives for the better.
In this article, we will look briefly at the history of Viagra and why it is used; we will also cover the pros and cons, side effects, and warnings.
Here are some key points about Viagra. More detail and supporting information is in the main article.
- Viagra was initially designed to treat hypertension and angina pectoris.
- Viagra's main competitors are Cialis (tadalafil) and Levitra (vardenafil).
- Viagra pills are blue and diamond-shaped.
- Individuals with kidney disease should not take Viagra.
- Some people use Viagra recreationally, although it is not thought to have any benefit for people without penile dysfunction.
What is Viagra?
Viagra was initially designed to help lower blood pressure but is now typically used to treat erectile dysfunction.
Viagra is the brand name for sildenafil citrate and is used for treating erectile dysfunction and pulmonary arterial hypertension.
Originally developed by scientists in the United Kingdom, it was brought onto the market by Pfizer Inc., an American pharmaceutical company.
Viagra is also sold under brand name Revatio.
Sildenafil citrate's chemical formula is C22H30N6O4S.
Viagra works by inhibiting an enzyme called cGMP-specific phosphodiesterase type 5 that delays degradation of cGMP, which controls blood flow in the penis.
Viagra side effects and precautions
According to clinical trial results, the most common side effects include:
- nasal congestion
- impaired vision
- photophobia (sensitivity to light)
- dyspepsia (indigestion)
Less commonly, some users have experienced cyanopsia (everything appears to have a tinted blue tinge).
In very rare cases, Viagra use can lead to nonarteritic anterior ischemic optic neuropathy (damage to the optic nerve).
Other potential side effects include:
- priapism (very rare) - a painful, long-lasting erection
- heart attack
- sudden hearing loss
- increased intraocular pressure
- ventricular arrhythmias
Since 2007, Viagra's labeling in the United States has included a warning of the potential risk of sudden hearing loss.
Viagra can decrease blood supply to the optic nerve, causing sudden vision loss. This very rare adverse event occurs mainly in people with heart disease, hypertension, diabetes, high cholesterol, or pre-existing eye problems. Nobody really knows whether the vision loss was caused by the Viagra.
People with HIV that take protease inhibitors should discuss using Viagra with their doctors - protease inhibitors increase the likelihood and severity of side effects. Experts say that these individuals should have no more than 25 milligrams, and not more often than every 48 hours.
If the individual is taking alpha-blockers, they should make sure they take Viagra at least 4 hours before or after to prevent dangerously low blood pressure.
The following individuals should not take Viagra (or check with their doctor first):
- Those on nitric oxide donors, nitrates, and organic nitrites.
- Men who are advised to refrain from sexual intercourse because of cardiovascular risk factors.
- People with severe hepatic impairment.
- People with kidney disease.
- Individuals with low blood pressure (hypotension).
- Those who have had a recent heart attack.
- Those who have had a recent stroke.
- Individuals with hereditary degenerative retinal disorders.
Exercise capacity - some athletes take Revatio to increase their exercise capacity, although there is little evidence to support this use.
A viagra overdose can be serious, although death is rare.
For erectile dysfunction, Viagra comes in blue, diamond-shaped pills, in doses of 25, 50, or 100 milligrams.
The individual takes a maximum of one pill in a 24-hour period, 30 minutes to 1 hour before sexual intercourse.
For pulmonary arterial hypertension, Viagra comes in white, round, film-coated tablets. People take one 20 milligram Revatio tablet three times a day.
A Viagra overdose can be serious. If you believe you have had more than the standard dosage, call a doctor or local Poison Control Center.
symptoms of an overdose might include:
- blurred vision and distorted vision
- papilledema - swelling in the optic nerve
- optic neuropathy - damage to the optic nerve
- tachycardia (increased heart rate)
- prolonged priapism
- rhabdomyolysis - break down of muscles
Deaths from viagra overdose are rare but possible.
Brief history of Viagra
Initially, Viagra was designed by Pfizer scientists working in Kent, England. They were, in fact, working on a drug for hypertension (high blood pressure) and angina pectoris (a symptom of ischemic heart disease).
During the phase 1 trials, it was noted that the drug did very little to prevent angina but did induce marked penile erections. Hitting the market in 1998, Viagra was the first oral treatment approved to treat erectile dysfunction in the U.S.
Viagra's meteoric rise to fame has seen it enter usage as an illicit drug. But, Viagra use in individuals without erectile dysfunction does not seem to have any effect. Although, researchers have noted that there is a significant placebo effect. On a similar note, there is no proven benefit for women taking the drug.
In 2008, Viagra generated some $1.93 billion of revenue for Pfizer.