What Is Viagra?

Introduction

“Viagra” is one of those words nearly everyone has heard. But what is it, how does it work, and does it really do what people think? This article explains, in a clear, no-jargon style, everything you need to know about Viagra: its purpose, mechanism, risks, legal status (especially in Australia), and how people use it responsibly.

Basic Definition

• Viagra is a brand name for a pharmaceutical drug whose active ingredient is sildenafil citrate. NPS Australia+2medsinfo.com.au+2
• It is used primarily to treat erectile dysfunction (ED), also called impotence — the difficulty in getting or maintaining an erection suitable for sexual activity. Australian Prescriber+3Healthdirect+3MedlinePlus+3
• Viagra belongs to a class of medicines called phosphodiesterase type 5 (PDE5) inhibitors. Australian Prescriber+3Healthdirect+3Medical News Today+3

It is not an aphrodisiac (i.e. it does not raise sexual desire) and does not initiate an erection by itself — sexual stimulation is still required. PMC+3Healthdirect+3FDA Access Data+3

How Viagra Works (Mechanism of Action)

To understand how Viagra works, we need a brief look at what happens during an erection:

1. When a man is sexually stimulated, nitric oxide is released in the penile tissue (inside the corpus cavernosum). This triggers a chain reaction producing a molecule called cGMP.
2. cGMP causes the smooth muscles in the walls of penile blood vessels to relax, allowing more blood to flow into the penis — this engorges it, creating an erection.
3. A natural enzyme, PDE5 (phosphodiesterase type 5), breaks down cGMP, which would cause the erection to subside.

Viagra (sildenafil) blocks PDE5, slowing the breakdown of cGMP. As a result, cGMP remains longer, muscle relaxation continues, and more blood stays in the penis — supporting an erection under sexual stimulation. FDA Access Data+3Medical News Today+3DrugBank+3

Because it works by enhancing a natural biochemical pathway, Viagra does not cause an erection if there is no sexual arousal or stimulation. Australian Prescriber+3Healthdirect+3FDA Access Data+3

Uses of Viagra

Erectile Dysfunction

This is the main and original use. Many men with ED get benefit from it. PMC+3NPS Australia+3Healthdirect+3

Pulmonary Arterial Hypertension (PAH)

Interestingly, sildenafil (the same active ingredient) is used under another brand name (e.g. “Revatio”) to treat high blood pressure in lung arteries (pulmonary hypertension). It helps by relaxing lung blood vessels. DrugBank+3MedlinePlus+3Cleveland Clinic+3

However, not all Viagra tablets are approved or suitable for that use — always follow medical direction.

Dosage, Onset, and Duration

• In Australia, a common starting dose is 50 mg taken about one hour before sexual activity. The dose may be adjusted (up or down) depending on effectiveness and side effects. Australian Prescriber
• It should not be taken more than once every 24 hours. Mayo Clinic+3MedlinePlus+3FDA Access Data+3
• Peak concentrations occur around 1–2 hours after ingestion. Australian Prescriber+2FDA Access Data+2
• The half-life (time to reduce concentration by half) is around 3 to 5 hours for most users. Cleveland Clinic+3Australian Prescriber+3FDA Access Data+3
• Effects may last about 4 hours, though this can vary by individual factors like metabolism, other drugs, health condition, and whether the user ate a heavy meal. Mayo Clinic+2Medical News Today+2

Note: A high-fat meal taken just before may delay absorption and reduce peak levels. FDA Access Data+2Australian Prescriber+2

Who Should and Should Not Use Viagra

Suitable Candidates

• Men with erectile dysfunction (after medical evaluation)
• Those without contraindications who are physically able to engage in sexual activity

Contraindications and Cautions

Viagra is not safe for everyone. Medical conditions and medications can make its use risky. Some key cautions:

• Never combine Viagra with nitrate drugs (used for chest pain, e.g. nitroglycerin). This combination can cause a severe drop in blood pressure, which could be life-threatening. FDA Access Data+2Healthdirect+2
• Men with serious cardiovascular disease, uncontrolled high or low blood pressure, recent heart attack or stroke, or severe liver or kidney impairment should use caution or avoid it. FDA Access Data+2PMC+2
• It should be used with caution in men who have anatomical deformation of the penis (e.g. Peyronie’s disease) or risk for priapism (prolonged erection). PMC+2FDA Access Data+2
• Some medications (especially inhibitors of CYP3A4, like ketoconazole, erythromycin) can interfere with sildenafil metabolism, increasing side effects or risk. Australian Prescriber+2FDA Access Data+2

Always consult a qualified physician before use. Self-medicating or ordering from unreliable sources can be dangerous.

Side Effects and Risks

Viagra is generally well tolerated in many users, but side effects occur. Common ones include:

• Headache
• Flushing (redness, warmth)
• Indigestion or heartburn
• Nasal congestion
• Dizziness
• Visual changes (e.g. blue tinge, light sensitivity) — rare Medical News Today+3Healthdirect+3FDA Access Data+3

More serious but rare risks:

• Priapism — an erection lasting more than 4 hours. Medical emergency.
• Sudden vision or hearing loss (very rare) FDA Access Data+1
• Significant drop in blood pressure in sensitive individuals
• Adverse interactions with other drugs

Because of these risks, prescription and medical supervision are essential.

Legal Status and Regulation in Australia

• In Australia, Viagra (sildenafil) is a prescription medicine — it is classified as Schedule 4 (S4). That means you must see a licensed doctor or prescriber to get it legally. NPS Australia+2Healthdirect+2
• The Therapeutic Goods Administration (TGA) closely monitors medicines. Products sold online with undisclosed sildenafil (i.e. “herbal” or “natural” supplements) have triggered safety alerts. Therapeutic Goods Administration (TGA)+1
• In 2024, the TGA issued alerts about online herbal supplements found to contain hidden sildenafil or tadalafil, warning that these can be unsafe and misleading. The Guardian

In short: only use Viagra under medical supervision, purchase from licensed pharmacies, and avoid unverified online sources.

Misconceptions and Myths

• Myth: Viagra increases sexual desire.
  → False. It does not affect libido; it only enhances blood flow under proper stimulation.
• Myth: Viagra causes permanent growth in penis size.
  → False. It helps with temporary erections but does not change penis anatomy permanently.
• Myth: Herbal “Viagra” works the same.
  → Many products labeled “herbal Viagra” are untested. Some have been found to contain hidden sildenafil or other drugs; some are outright counterfeits. Wikipedia+1
• Myth: It works instantly or forever.
  → It takes up to about an hour to take effect and lasts a few hours. It is not permanent.

Use in Practice: Tips for Patients

• Discuss health conditions (heart, blood pressure, liver, kidney) and all medications with your doctor.
• Begin with a standard dose (e.g. 50 mg) and adjust only under medical supervision.
• Avoid heavy meals right before taking it — they slow absorption.
• Abstain from excessive alcohol or recreational drugs.
• Do not use more often than once per 24 hours.
• If an erection persists over 4 hours, get emergency medical attention.
• Report any sudden vision or hearing changes immediately.

Research and Trends

• Over the years, sildenafil (Viagra) has been widely studied and remains a cornerstone in treating ED.
• In Australia and New Zealand, analyses show that sildenafil is relatively accessible and cost-effective compared to some other therapies. ScienceDirect
• Newer ED medications (other PDE5 inhibitors) offer alternatives with different onset or duration profiles. Healthy Male