Generic Name: sildenafil
Brand Name: Viagra
Drug Class: PAH, PDE-5 Inhibitors, Phosphodiesterase-5 Enzyme Inhibitors
What is sildenafil, and what is it used for?
Viagra (sildenafil) is an oral drug that is used for treating impotence (or erectile disfunction, ED, the inability to attain or maintain a penile erection). It is in a class of drugs called phosphodiesterase inhibitors (PDE-5 inhibitors) that also includes
- tadalafil (Cialis),
- vardenafil (Levitra, Staxyn ODT), and
- avanafil (Stendra).
It has been estimated that impotence affects 140 million men worldwide. Over half of all men with impotence are thought to have some physical (medical) cause. The remainder is believed to have psychogenic causes of impotence. Medical causes of impotence include diabetes and circulatory, neurological, or urological conditions.
Penile erection is caused by the engorgement of the penis with blood. This engorgement occurs when the blood vessels delivering blood to the penis increase the delivery of blood and the blood vessels carrying blood away from the penis decrease the removal of blood. Under normal conditions, sexual stimulation leads to the production and release of nitric oxide in the penis. Nitric oxide then activates the enzyme, guanylate cyclase, which causes the production of cyclic guanosine monophosphate (cGMP). It is the cGMP that is primarily responsible for the erection by affecting the amount of blood that the blood vessels deliver and remove from the penis.
Viagra inhibits an enzyme called phosphodiesterase-5 (PDE5) which destroys the cGMP. Thus, Viagra prevents the destruction of cGMP and allows cGMP to accumulate and persist longer. The longer cGMP persists, the more prolonged the engorgement of the penis. The FDA approved Viagra in March 1998.
What are the side effects of sildenafil?
Approximately 15% of persons taking Viagra experience side effects. The most common side effects are:
- facial flushing (1 in 10),
- headaches (1 in 6),
- stomach pain,
- nasal congestion,
- nausea,
- dizziness,
- rash,
- urinary tract infections (UTIs)
- diarrhea, and
- an inability to differentiate between the colors green and blue.
What is the dosage for sildenafil?
- The usual recommended dose is 25 to 100 mg 1 hour before sexual activity.
- The maximum dose is 100 mg daily.
- The elderly (over 65 years of age) should start at 25 mg before sexual activity.
- Sildenafil is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When sildenafil is taken with a high fat meal, the rate of absorption is reduced, with an average delay in the time to maximal concentration of 1 hour.
What drugs interact with sildenafil?
- Viagra increases the effects of the blood pressure lowering medications. It also increases the blood pressure lowering effects of nitrates, for example, isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, Ismo, Monoket), nitroglycerin (Nitro-Dur, Transderm-Nitro) that are used primarily for treating angina. Patients taking nitrates should not receive Viagra.
- Patients should not combine Viagra with other PDE5 inhibitors (for example, vardenafil [Levitra], tadalafil [Cialis]).
- Cimetidine (Tagamet), erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), atazanavir (Reyataz), and mibefradil (Posicor) can cause marked increases in the amount of Viagra in the body. Patients taking these medications should be observed carefully if sildenafil is used.
- It is expected that rifampin will decrease blood levels of Viagra and probably reduce its effectiveness.
![](https://images.medicinenet.com//images/slideshow/erectile-dysfunction-s1-baseball-player-after-strikeout.jpg)
SLIDESHOW
Erectile Dysfunction (ED) Causes and Treatment See SlideshowIs sildenafil safe to take if I'm pregnant or breastfeeding?
- Although extensive testing in animals has demonstrated no negative effects on the fetus, Viagra has not been studied in pregnant women. There is no effect on sperm count or motility of sperm in men.
- It is not known whether sildenafil is excreted into breast milk.
What else should I know about sildenafil?
What preparations of sildenafil are available?
- Sildenafil (Viagra) is a blue, film-coated, rounded, diamond-shaped tablet that comes in 25, 50, and 100 mg tablets for treating impotence.
How should I keep sildenafil stored?
- Tablets should be kept at room temperature between 15 C and 30 C (59 F and 86 F).
Summary
Sildenafil is a medication prescribed for the treatment of impotence (erectile dysfunction, ED) caused by medical or psychological conditions. The most common side effects are facial flushing (1 in 10), headaches (1 in 6), stomach pain, nasal congestion, nausea, dizziness, rash, urinary tract infections (UTIs), diarrhea, and an inability to differentiate between the colors green and blue. Do not combine Viagra with other PDE5 inhibitors (for example, vardenafil [Levitra], tadalafil [Cialis]).
Multimedia: Slideshows, Images & Quizzes
-
Low Blood Pressure (Hypotension): Symptoms, Signs, Causes
What is low blood pressure (hypotension)? Explore low blood pressure causes, symptoms, and signs. Discover what is considered low...
-
Erectile Dysfunction (ED) Causes and Treatment
Having erection problems? What is erectile dysfunction (ED)? Learn about erectile dysfunction causes and treatments such as drugs...
-
Healthy Aging: Better Sex After 50
It's never too late to improve your sex life. Learn how older adults can overcome common health conditions affecting seniors over...
-
Sex-Drive Killers: The Causes of Low Libido
Noticing a lack of intimacy with your partner? Here we explore how stress, lack of sleep, weight gain, depression and low T can...
-
Sex Tips for Men: How to Have a Better Sex Life
Learn sex tips for men that lead to more sexual pleasure such as better communication, focusing on pleasurable sensations,...
-
Quiz: Is Your Penis Normal?
Can a man break his penis? Take this quiz to learn myths about size, common conditions, general facts, and other things you...
-
Sex Quiz: Love & Relationships Facts
Relationships, sex, and love! Could it be that what motivates physical attraction in us may be all in our minds? Take the Sex &...
-
Erectile Dysfunction (Impotence) Quiz: Causes & Treatment
Did you know that certain medical condition may be responsible for ED? Some causes of impotence are medically treatable and...
-
Screening Tests Every Man Should Have
Getting the right screening test at the right time is one of the most important things a man can do for his health. Learn at what...
-
19 Health Problems in Men: Snoring, Hair Loss, and More
What are the biggest body health issues that plague men? Most men struggle with belly fat, back hair, sweating, erectile...
-
Picture of Penis
The penis is the male sex organ, reaching its full size during puberty. See a picture of the Penis and learn more about the...
-
Men's Health: What Foods Should Men Eat for Good Health?
What foods have the most health benefits for men? For losing weight, gaining muscle, and lowering your risk of prostate cancer,...
-
19 Secrets Women Wish You Knew With Pictures
There are secrets women would love for you to know. These relationship secrets are based on the study of healthy, happy couples,...
-
For Men Only: 15 Ways to Stay On Top of Your Game
See how first impressions, staying active, good hygiene and more lifestyle tips can improve your overall health and well-being.
Related Disease Conditions
-
What Supplements Are Good for Female Libido?
Female sexual desire is a complex phenomenon governed by emotional and psychological factors, as well as hormones. The majority of female-enhancement products comprise a combination of natural herbs, minerals, and vitamins.
-
Night Sweats
Night sweats are severe hot flashes that occur at night and result in a drenching sweat. The causes of night sweats in most people are not serious, like menopause in women, sleep apnea, medications, alcohol withdrawal, and thyroid problems. However, more serious diseases like cancer and HIV also can cause night sweats. Your doctor will treat your night sweats depending upon the cause. You may experience other signs and symptoms that are associated with night sweats, which depend upon the cause, but may include, shaking, and chills with a fever caused by an infection like the flu or pneumonia; unexplained weight loss due to lymphoma; women in perimenopause or menopause may also have vaginal dryness, mood swings, and hot flashes during the day; and low blood sugar in people with diabetes. Other causes of night sweats include medications like NSAIDs (aspirin, acetaminophen, ibuprofen (Motrin, Advil), and naproxen (Aleve, Naprosyn), antidepressants, sildenafil (Viagra), and abuse of prescription or illegal drugs and drug withdrawal; hormone disorders like pheochromocytoma and carcinoid syndrome; idiopathic hyperhidrosis; infections like endocarditis, AIDs, and abscesses; alcoholism and alcohol withdrawal; drug abuse, addiction, and withdrawal; and stroke. A doctor or other health care professional can treat your night sweats after the cause has been diagnosed.
-
Sexual Problems in Men
Male sexual dysfunction can be caused by physical or psychological problems. Common sexual problems in men include erectile dysfunction (impotence or ED), premature ejaculation, and loss of libido. Treatment for sexual dysfunction in men may involve medication, hormone therapy, psychological therapy, and the use of mechanical aids.
-
Atherosclerosis and Erectile Dysfunction
Second Source article from WebMD
-
Prostate Cancer: Erectile Dysfunction
Second Source article from The Cleveland Clinic
-
How Long Does it Take to Cure Erectile Dysfunction?
Erectile dysfunction is defined as your inability to get or maintain an erection. The length of time that it takes to cure your ED will ultimately depend on the cause.
-
What Causes Weak Erection?
Medically, a weak erection is also referred to as erectile dysfunction. The erection of the penis depends on many factors, such as the person’s age, overall health, hormone levels, nerves, blood flow, mental status, and emotions. A weak erection results when these factors get affected.
-
Erectile Dysfunction (ED, Impotence)
Erectile dysfunction (ED, impotence) is the failure to achieve or maintain an erection. There are many potential underlying causes of erectile dysfunction, including stress and emotional problems, brain dysfunction, problems with blood supply to the penis, and structural problems with the penis.
-
How Young Can You Be for Viagra?
Viagra (sildenafil) is one of the world’s most popular drugs that has changed the lives of countless couples. The FDA has approved the use of sildenafil only in “men” older than 18 years.
-
What Is the Fastest Way To Cure Erectile Dysfunction?
Learn about the symptoms of erectile dysfunction, treatment options, and the quickest way to help you resolve the condition. It is more likely that you'll develop erectile dysfunction as you get older, but aging itself does not cause erectile dysfunction. Many factors can cause erectile dysfunction, including those that affect your endocrine, vascular, and nervous systems. What is erectile dysfunction, and what are the signs and symptoms? Learn about the risks and causes of erectile dysfunction and what treatments are available for erectile dysfunction.
-
How Long Can Erectile Dysfunction Last?
Erectile dysfunction is the inability to get or maintain an erection when you want one. Erectile dysfunction (ED) can last a few months to years.
-
Why Do I Keep Losing My Erection?
If you keep losing an erection during sex, you are not alone. Erectile dysfunction (ED) is common and occurs for a wide variety of reasons, from psychological to physical.
-
Is There Anything Over-the-Counter That Works Like Viagra?
Over-the-counter treatment for erectile dysfunction does exist, in the form of ED pumps and pills. However, it’s best to consult your doctor before starting these treatments.
-
Scleroderma
Scleroderma is an autoimmune disease of the connective tissue. It is characterized by the formation of scar tissue (fibrosis) in the skin and organs of the body, leading to thickness and firmness of involved areas. Scleroderma is also referred to as systemic sclerosis, and the cause is unknown. Treatment of scleroderma is directed toward the individual features that are most troubling to the patient.
-
What Does Viagra Do to a Woman?
Women with certain sexual dysfunctions may benefit from taking Viagra since the pill increases blood flow to the genitals, which could help increase arousal, sensitivity and orgasmic function.
-
Peyronie's Disease (Curvature of the Penis)
Peyronie's disease or curvature of the penis (Peyronie disease) is a condition in which scar tissue develops inside the penis. This scar tissue causes the penis to develop an abnormal curvature in the scarred area. At this time, there is no known cause of Peyronie's disease. Symptoms of Peyronie's disease include pain during intercourse or ejaculation, erectile dysfunction (ED, impotence), the inability to have sexual intercourse, anxiety, stress, an indentation of the shaft at the site where there is plaque or scarring, and an angulation of the penis when erect or flaccid. There is no cure for Peyronie's disease, however, there are medications that can reduce symptoms of the disease. Surgery or penile implants may be an option for severe cases.
-
Multiple Sclerosis (MS) Symptoms and Treatments
Multiple sclerosis (MS) symptoms vary from person to person and can last for days to months without periods of remission. Symptoms of MS include sexual problems and problems with the bowel, bladder, eyes, muscles, speech, swallowing, brain, and nervous system. The early symptoms and signs of multiple sclerosis usually start between ages 20-40. MS in children, teens, and those over age 40 is rare. Treatment options for multiple sclerosis vary depending on the type and severity of symptoms. Medications may be prescribed to manage MS symptoms.
-
Balanitis (Inflammation of the Head of the Penis)
Balanitis is a condition in which the skin of the head of the penis becomes inflamed. If the foreskin is also inflamed, it is referred to as balanoposthitis. Balanitis usually occurs in uncircumcised males with symptoms of pain, swelling, and redness at the head of the penis. Often, balanitis is caused by poor hygiene or some medical conditions such as diabetes, and yeast infections. Treatment for balanitis is directed at the cause of the condition and may include creams or other medications.Balanitis is not an STD; however, it may have similar symptoms.
-
What Is Diabetic Neuropathy?
Diabetic neuropathy a condition in which nerve damage has occurred as a complication of diabetes. The pain from the nerve damage can be severe with tingling or numbness in the part of the body affected. Diabetic neuropathy can occur anywhere in the body. Diabetic neuropathy can cause symptoms like intense pain, numbness, burning, or tingling in the part of the body affected by the condition. There are four types of neuropathy include peripheral, autonomic, proximal and focal. Natural therapies and medications may help relieve the pain and other symptoms of diabetic neuropathy.
-
Can Erectile Dysfunction Caused By Diabetes Be Reversed?
Erectile dysfunction is a frustrating condition where your penis cannot get or maintain an erection firm enough for sex. There is no specific treatment to reverse damage to blood vessels caused by diabetes, there are several options to help you have erections.
-
Pulmonary Hypertension
Pulmonary hypertension is elevated pressure in the pulmonary arteries that carry blood from the lungs to the heart. The most common symptoms are fatigue and difficulty breathing. If the condition goes undiagnosed, more severe symptoms may occur. As pulmonary hypertension worsens, some people with the condition have difficulty performing any activities that require physical exertion. While there is no cure for pulmonary hypertension, it can be managed and treated with medications and supplemental oxygen to increase blood oxygen levels.
-
Early Signs and Symptoms of Penis Cancer
Penile cancer is a relatively rare type of cancer arising from the skin and tissues of the penis. It affects the skin and tissues of the penis. It occurs when normal cells in the penis become cancerous and grow rapidly out of control, forming a tumor. Penile cancer can spread to other parts of the body.
-
What Is the Female Version of Viagra Called?
The FDA approved two versions of female Viagra to treat female sexual dysfunction, which are called flibanserin (Addyi) and bremelanotide.
-
Priapism (Penis Disorder)
Priapism is a penis disorder characterized by a prolonged, unwanted erection of the penis. Medical conditions, trauma, or medications can cause priapism. There are three categories of priapism: ischemic priapisim, non-ischemic priapism, and stuttering priapism. Treatment includes medical intervention, medication, and at times, surgery.
-
Types of Penis Disorders
Penis disorders may affect men’s sexual life, fertility and overall well-being. Some are minor and don’t cause many issues. However, some may lead to serious emergencies. There are many different types of penis disorders.
-
What Are the Best Three Exercises for Erectile Dysfunction?
What Are the Best Three Exercises for Erectile Dysfunction? Learn whether exercises can help and what other treatments can help to relieve your symptoms.
-
What Is Libido in a Man?
Libido in a man is his sex drive, influenced by the symbiotic relationship between hormones and neurotransmitters—testosterone, dopamine, serotonin, and glutamate.
-
What Is the Best Medicine for Erectile Dysfunction?
The best medicine for erectile dysfunction (ED) depends on the cause of your condition, as well as your budget and lifestyle.
-
Is Erectile Dysfunction Permanent?
Erectile dysfunction (ED) occurs when you have trouble getting or maintaining an erection on a regular basis. Erectile dysfunction is treated with lifestyle, behavioral, medical, and surgical interventions.
-
Phimosis (Paraphimosis)
Phimosis and paraphimosis are penis disorders. Phimosis is a condition where the foreskin can't retract behind the head of the penis. Symptoms can lead to swelling of the penis, or painful erection and urination. Paraphimosis is a condition that occurs when the foreskin is retracted behind the head of the penis and can't return to it's original position. Symptoms include pain and swelling of the penis. You need to be treated by a doctor or other healthcare professional for these penis problems.
-
Men's Health
Men's health is an important component to a happy lifestyle and healthy relationships. Eating healthy, exercise, managing stress, and knowing when to have medical tests for a particular age is key to disease prevention in men.
-
Why Do I Have Discharge From My Penis?
Penis discharge that is not due to sexual arousal is considered abnormal and may be caused by various conditions such as urinary tract infections (UTIs), STDs, and more. Learn more about causes, types, and treatments.
-
Do Urologists Treat Erectile Dysfunction?
Urologists are the doctors that can examine, diagnose and treat your erectile dysfunction (ED).
-
What Is the Main Cause of Erectile Dysfunction?
Penile erection is a complex process in which the brain, nerves, muscles and blood vessels play a major role. The main causes of erectile dysfunction include psychological and health conditions, medications, trauma, and lifestyle factors. These may include depression, anxiety, stress, diabetes, cardiovascular disease, antiandrogens, appetite suppressants, and antidepressants, trauma due to an injury or a surgery, lack of exercise, or addictions (smoking).
-
Can Erectile Dysfunction Become Permanent?
Erectile dysfunction (ED) is the medical term for impotence. Treatments for erectile dysfunction include lifestyle changes, psychotherapy, medications, devices, and surgery.
-
How Do I Increase My Low Libido?
There is no “one-size-fits-all” technique to increase libido; however, doctors can successfully treat a low sex drive with correct diagnosis and medical therapy.
-
Is Erectile Dysfunction Always Permanent?
Erectile dysfunction is defined as your inability to get or maintain an erection when you want to. Erectile dysfunction is treatable with counseling, medications, injections, physical devices, and other medical treatments.
-
Sexual Health
Sexual health information including birth control, impotence, herpes, sexually transmitted diseases, staying healthy, women's sexual health concerns, and men's sexual health concerns. Learn about the most common sexual conditions affecting men and women.
-
How Do You Fix Erectile Dysfunction at 50?
Erectile dysfunction isn’t necessarily a normal part of aging. Fix erectile dysfunction at 50 by making lifestyle changes, getting psychological help, getting medical or mechanical treatment, or considering surgery.
-
How Do You Boost Low Libido?
Low libido can be caused by a wide variety of factors, from stress to hormonal changes. Here are 10 ways to spice up your sex life and boost low libido.
Treatment & Diagnosis
- Sex & Love FAQs
- Impotence Erectile Dysfunction FAQs
- Is Your Penis Normal FAQs
- 8 Natural Remedies for Erectile Dysfunction (ED)
- Medication Disposal
- Dangers of Mixing Medications
- Viagra: The Little Blue Pill That Could
- Drugs: The Most Common Medication Errors
- Drugs: Buying Prescription Drugs Online Safely
- Erectile Dysfunction Drugs: Drug Interactions
- How To Reduce Your Medication Costs
- Pharmacy Visit, How To Get The Most Out of Your Visit
- Indications for Drugs: Approved vs. Non-approved
- Viagra - Impotence Treatment Update
- Viagra and Nitrates Don't Mix
- Radio ID Tags For US Drugs (RFID)
- Can oral diabetes medications cause impotence?
- Erection Protection: Is Erectile Dysfunction (ED) Prevention Possible?
- Effective Erectile Dysfunction Treatments: What to Do After an Impotence Diagnosis
- What Causes Erectile Dysfunction (Impotence)?
- Grapefruit Juice and Drug Interactions
- Things You Should Know About the Penis
- Generic Drugs, Are They as Good as Brand-Names?
- Sexual Satisfaction: Give Your Libido a Lift
- Erectile Dysfunction and Weight Loss
Medications & Supplements
- Flomax and Viagra for BPH Treatment
- sildenafil (erectile dysfunction) - oral, Viagra
- tadalafil (erectile dysfunction) - oral, Cialis
- Drugs: Questions to Ask Your Doctor or Pharmacist about Your Drugs
- avanafil
- Drug Interactions
- Side Effects of Viagra (sildenafil)
- tadalafil, Cialis, Adcirca
- vardenafil (Levitra, Staxyn ODT)
- yohimbine
- testosterone
- alprostadil suppository - penile, Muse
Prevention & Wellness
- What Is Natural Viagra for Females?
- Is This Normal to Have Bumps on My Penis?
- Can Nitric Oxide Supplements Reverse Erectile Dysfunction (ED)?
- Senior Health (Successful Aging)
- Does Maca Root Work Like Viagra, and How Long Does It Take to Activate and Work?
- 9 Natural Viagra Alternatives to Help Increase Sex Drive in Both Men and Women
![FDA Logo](https://images.medicinenet.com/images/logo_fda.png)
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
REFERENCE:
FDA Prescribing Information.