Viagra® / Revatio®
Sildenafil Citrate
Version 2025-04 · Last reviewed April 1, 2025 · Methodology
List Price
$70 per pill (brand Viagra)
With Insurance
$5-20
The Short Version
Evidence summary
Viagra (Sildenafil Citrate) is a PDE5 Inhibitor (Phosphodiesterase Type 5) prescribed for Erectile dysfunction and Pulmonary arterial hypertension (as Revatio). FDA-approved in 1998.
Effects begin within 30-60 minutes on an empty stomach. Duration is typically 4-6 hours.
The most commonly reported side effects are Headache (16-28%), Facial flushing (10-20%), Dyspepsia (indigestion) (7-17%). Most common side effect; usually mild and self-limiting. OTC pain reliever can help.
Review the funding details in the evidence section below.
What This Really Costs
Long-term cost projection based on current pricing
Monthly
$6
$13 w/ insurance
without insurance
Annual
$72
$156 w/ insurance
without insurance
10 Years
$720
$1.6K w/ insurance
without insurance
30 Years
$2.2K
$4.7K w/ insurance
without insurance
Lifestyle alternative: $0/month in prescriptions. Weight loss and exercise — 31% of obese men recovered normal erectile function with weight loss + exercise.
The average American retiree spends $165,000 on healthcare over their lifetime (Fidelity, 2024). Informed choices today compound over decades.
Quick Answers
Now what?
You've read the evidence. Here are your next steps.
How It Works
Sildenafil inhibits phosphodiesterase type 5 (PDE5), an enzyme that breaks down cyclic GMP (cGMP) in the smooth muscle of penile blood vessels. During sexual arousal, nitric oxide is released, producing cGMP, which causes smooth muscle relaxation and blood flow into the penis. By preventing cGMP breakdown, sildenafil amplifies the natural erection process. It does NOT create arousal — it enhances the vascular response to existing arousal.
Why the side effects happen
Headache, flushing, and nasal congestion are all caused by vasodilation — the same mechanism that produces the intended effect, just in other blood vessels. The blue vision tint comes from cross-inhibition of PDE6 in the retina. The dangerous interaction with nitrates occurs because both nitrates and sildenafil increase cGMP — causing potentially fatal blood pressure drops.
When Will I Feel It?
Effects begin within 30-60 minutes on an empty stomach. Duration is typically 4-6 hours.
Sildenafil is absorbed and reaches effective blood levels. High-fat meals can delay absorption by up to 1 hour.
Maximum plasma concentration. Best erectile response during this window.
Effect gradually diminishes. Half-life is 3-5 hours. Some residual effect may persist longer.
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Metabolic & Lifestyle Alternatives
Addressing Root Causes of Erectile Dysfunction
Erectile dysfunction is primarily a vascular condition — the same arterial disease that causes heart attacks causes ED. In many men, ED is the first sign of cardiovascular disease. Addressing the underlying vascular health can improve or resolve ED in a significant proportion of men.
Important context: Evidence quality varies across these approaches. Some are well-studied with randomized controlled trial data; others are based on observational or smaller studies. These interventions are not guaranteed to replace medication for all patients. Discuss with your doctor whether any of these are appropriate for your clinical situation.
Weight loss and exercise
Obesity, insulin resistance, and sedentary lifestyle are the leading modifiable causes of ED. The Italian EMAS study found that lifestyle intervention alone restored erectile function in 31% of obese men with ED.
31% of obese men recovered normal erectile function with weight loss + exercise
Cardiovascular fitness
ED and cardiovascular disease share the same pathophysiology — endothelial dysfunction. Improving cardiovascular fitness improves nitric oxide production (the same mechanism sildenafil enhances).
Men who exercise 150+ min/week have 30-40% lower ED risk
Mediterranean diet
The Mediterranean diet improves endothelial function, reduces inflammation, and is associated with better erectile function in multiple studies.
Associated with significantly lower ED prevalence; improves International Index of Erectile Function scores
Pelvic floor exercises (Kegels)
Pelvic floor muscle training has Level 1 evidence for ED, particularly for men with venous leak. RCTs show significant improvement.
40% of men regained normal erectile function after 3 months of pelvic floor exercises
Alcohol and smoking cessation
Alcohol impairs erectile function acutely and chronically. Smoking damages blood vessels and is one of the strongest independent risk factors for ED.
Smoking cessation associated with 25% improvement in erectile function within 6 months
Testosterone optimization (if deficient)
Low testosterone contributes to ED in some men. However, testosterone alone is often insufficient — it primarily improves libido rather than erection mechanics. Testing before supplementation is essential.
Improves libido and erectile function in truly deficient men (total T <300 ng/dL); limited benefit if levels are normal
Key Studies
How It Compares
Sildenafil was the first PDE5 inhibitor and remains the most prescribed. Generic availability has made it the cheapest option ($1-3/pill). Tadalafil (Cialis) offers a longer duration and daily dosing option.
Strengths
- Extremely cheap as generic ($1-3/pill vs $70+ brand)
- Decades of safety data
- Rapid onset (30-60 min)
- Well-understood mechanism and interactions
Weaknesses
- Short duration (4-6 hours vs 36 hours for tadalafil)
- Food delays absorption
- Must be taken on-demand (no daily low-dose option like tadalafil 5mg)
Clinically Preferred Alternatives
Global Prescribing & Pricing
Sildenafil is the most recognized ED medication globally; generic availability has transformed pricing
United States
$8-40 (generic) / $1,600+ (brand)/mo
Generic widely available since 2017; brand Viagra still marketed at massive premium
Most insurance plans do not cover ED medications; patient pays out of pocket
Rarely covered for ED
United Kingdom
~$2-8 (generic)/mo
Available over-the-counter since 2018 (Viagra Connect 50mg)
NHS covers for specific conditions; OTC access reduces barriers
Limited NHS coverage; OTC available
France
~$3-10 (generic)/mo
Prescription required; widely prescribed
Not reimbursed by Sécurité Sociale for ED
Not covered for ED
Germany
~$3-10 (generic)/mo
Prescription required
Not covered by statutory insurance for ED (considered lifestyle medication)
Not covered for ED
Japan
~$10-25 (generic)/mo
Prescription required; generic available since 2014
Not covered by national insurance for ED
Not covered for ED
ED medications are classified as "lifestyle drugs" in most countries and are not covered by insurance. The UK is notable for making sildenafil available over-the-counter. Generic sildenafil costs $1-3 per pill — brand Viagra still charges $70+ per pill for the identical molecule, sustained purely by marketing.
Clinical Trials & Funding
Understanding who funds research helps contextualize results. Industry-funded trials are not automatically invalid — they undergo the same FDA review — but declared conflicts and sponsor effects are worth knowing. All linked trials can be verified on ClinicalTrials.gov.
Funding Sources
All pivotal erectile dysfunction trials were funded by Pfizer. Sildenafil was originally developed as a cardiovascular drug (for angina) — the ED application was discovered incidentally during trials. Pfizer then pivoted the entire development program to the far more lucrative ED market.
Declared Conflicts of Interest
Pfizer funded all major trials, employed lead investigators, and created one of the most successful direct-to-consumer advertising campaigns in pharmaceutical history. The marketing budget for Viagra has exceeded $100 million annually.
Key Efficacy Results
Effective for ED in 56-84% of men depending on etiology; works within 30-60 minutes; duration 4-6 hours
Referenced Studies
Each study carries a Cochrane RoB-2 risk-of-bias badge — tap the badge for details.
Evidence & Transparency
Cochrane RoB-2 (Risk of Bias)
Badges reflect an editorial assessment using Cochrane's RoB-2 tool domains: randomization, intervention deviation, missing data, outcome measurement, and selective reporting. These are not certified Cochrane reviews. Learn more ↗
CMS Open Payments
Manufacturer payment disclosures are reported via the CMS Sunshine Act. Disclosure is legally required and does not imply bias or misconduct. Language uses "may," "suggests," or "appears" — never definitive clinical claims. CMS Open Payments ↗
Live Clinical Trials
Live from ClinicalTrials.gov · refreshed every 4 hours
Currently enrolling, active, and recently completed studies involving Sildenafil Citrate. Data is pulled directly from the U.S. National Library of Medicine.
Recent Research
Live from PubMed · peer-reviewed literature · refreshed every 4 hours
Most recently indexed clinical trials and systematic reviews mentioning Sildenafil Citrate in PubMed.
Source Documentation
Structured citations for referenced clinical trials
Each referenced trial is listed with its registry ID, funding source, and bias assessment. Use the copy button to generate a formatted citation.
| Trial | Registry ID | Cite |
|---|---|---|
| Goldstein et al. 1998 (Pfizer) | PMID:9578024 |
Bias ratings use Cochrane RoB-2 methodology. Editorial assessment — not a certified Cochrane review.
Our MethodologyMedical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Common Side Effects
While taking this medication, you may experience the following common side effects. We've included tips on how to manage them.
Headache
16-28%Most common side effect; usually mild and self-limiting. OTC pain reliever can help.
Facial flushing
10-20%Vasodilation effect; resolves within hours
Nasal congestion
4-9%Common; usually mild
Dyspepsia (indigestion)
7-17%Take on an empty stomach to reduce
Dizziness
2-4%Blood pressure lowering effect; rise slowly
Visual changes (blue tint)
3-11%Transient blue-green color tinge; caused by PDE6 cross-reactivity in retina. Resolves within hours.
Back pain
2-4%More common with tadalafil but reported with sildenafil too
Serious Adverse Effects
- • Priapism (erection lasting >4 hours — medical emergency)
- • Sudden vision loss (NAION — non-arteritic anterior ischemic optic neuropathy; very rare)
- • Sudden hearing loss (very rare)
- • Severe hypotension (especially with nitrates — can be fatal)
- • Cardiac events in patients with underlying cardiovascular disease
Drug Interactions
Major Interactions (Avoid)
Moderate Interactions (Caution)
Food Interactions
When to Contact Your Doctor
This medication requires ongoing medical supervision. The following situations warrant a prompt conversation with your prescribing physician — do not wait for your next scheduled appointment.
Contact soon if you notice
- Priapism (erection lasting >4 hours — medical emergency)
- Sudden vision loss (NAION — non-arteritic anterior ischemic optic neuropathy; very rare)
- Sudden hearing loss (very rare)
- Severe hypotension (especially with nitrates — can be fatal)
- No withdrawal symptoms expected
Also discuss if you want to
- Review whether this medication is still appropriate for you
- Consider dosage adjustments based on response
- Explore lifestyle or non-drug alternatives
- Understand stopping or tapering options
- Plan monitoring labs and follow-up
In the US, call 911 or go to the nearest emergency room for severe symptoms. Poison Control: 1-800-222-1222.
Special Populations
Safety classifications for specific groups — discuss with your provider before use.
Primarily prescribed for male erectile dysfunction. Investigated for pre-eclampsia but not standard of care.
Male medication. No relevance to breastfeeding.
Only Revatio (20mg for pulmonary hypertension) has pediatric use data.
Start at 25mg. Greater sensitivity to hypotension. Check cardiovascular fitness before prescribing.
Start at 25mg in severe renal impairment (CrCl <30).
Start at 25mg in hepatic impairment. Sildenafil clearance reduced.
FDA Adverse Event Reports
Patient-filed reports from the FDA FAERS database · refreshed daily
Community Reports
User-reported experiences — anonymous & anecdotal
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Stopping This Medication Safely
Sildenafil is used on-demand (as needed) for erectile dysfunction. There is no physical dependence, no withdrawal syndrome, and no need for tapering. It can be stopped at any time without adverse effects.
What Published Research Shows About Stopping This Medication
This summarizes what published research documents — it is not personal medical advice. Any changes to your medication require discussion with your prescribing physician.
- ·No taper required — sildenafil can be stopped at any time
- ·If used daily for pulmonary hypertension (Revatio), discuss with your prescriber before stopping
Warning Symptoms — Contact Your Doctor If You Experience:
- No withdrawal symptoms expected
- If ED worsens after stopping, this reflects the underlying condition, not drug withdrawal
Never change or stop a medication without consulting your prescribing physician.
Questions for Your Doctor
Questions to Ask
- 1.Could my ED be an early sign of heart disease?
- 2.Should I have my cardiovascular health evaluated?
- 3.Is my testosterone level normal?
- 4.Could any of my other medications be causing this?
- 5.Would lifestyle changes be enough without medication?
Lab Tests to Request
- Cardiovascular risk assessment (ED is a vascular warning sign)
- Fasting glucose / HbA1c (diabetes screening)
- Lipid panel
- Testosterone level (total and free)
- Blood pressure
Medical Disclaimer
The information on this page is compiled from publicly available clinical trial data, FDA prescribing information, and peer-reviewed literature. It is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Individual responses to medications vary. Always consult a qualified healthcare provider before starting, stopping, or changing any medication.
Frequently Asked Questions About Viagra® / Revatio®
- What is Viagra® / Revatio® used for?
- Viagra® / Revatio® (Sildenafil Citrate) is a PDE5 Inhibitor (Phosphodiesterase Type 5) manufactured by Generic (originally Pfizer). FDA-approved indications include: Erectile dysfunction; Pulmonary arterial hypertension (as Revatio).
- What are the common side effects of Viagra® / Revatio®?
- Common side effects of Viagra® / Revatio® include: Headache (16-28%); Facial flushing (10-20%); Nasal congestion (4-9%); Dyspepsia (indigestion) (7-17%); Dizziness (2-4%).
- How much does Viagra® / Revatio® cost?
- Viagra® / Revatio® list price is approximately $70 per pill (brand Viagra). With insurance it typically costs $5-20; without insurance approximately $2-10 (generic).
- Who funded the clinical trials for Viagra® / Revatio®?
- All pivotal erectile dysfunction trials were funded by Pfizer. Sildenafil was originally developed as a cardiovascular drug (for angina) — the ED application was discovered incidentally during trials. Pfizer then pivoted the entire development program to the far more lucrative ED market.
- How strong is the clinical evidence for Viagra® / Revatio®?
- Key studies: Goldstein 1998 (original Viagra trial), multiple Pfizer-funded RCTs. Effective for ED in 56-84% of men depending on etiology; works within 30-60 minutes; duration 4-6 hours Potential conflicts of interest: Pfizer funded all major trials, employed lead investigators, and created one of the most successful direct-to-consumer advertising campaigns in pharmaceutical history. The marketing budget for Viagra .
- Are there non-drug alternatives to Viagra® / Revatio®?
- Erectile dysfunction is primarily a vascular condition — the same arterial disease that causes heart attacks causes ED. In many men, ED is the first sign of cardiovascular disease. Addressing the underlying vascular health can improve or resolve ED in a significant proportion of men. See the Alternatives tab for full details.
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