Is generic sildenafil the same as Viagra?

It contains the same active substance at the same strength, and a generic is approved only after demonstrating that it delivers that substance into the blood in the same way as the original. The tablet colour, shape and inactive ingredients can differ.

Why does the label mention pulmonary hypertension?

The same molecule is approved separately under the name Revatio for pulmonary arterial hypertension, at a lower strength and a different dosing schedule. It is the same substance holding two approvals for two conditions, which is why both labels appear on this page.

What makes nitrates dangerous with it?

Both lower blood pressure through related pathways, and together the drop can be severe. The label lists this as a contraindication rather than a caution, which is the strongest category it has.

Sildenafil

The first medicine approved for erectile dysfunction, on the market since 1998 and off patent everywhere, which is why it is now the cheapest of the four.

Class: PDE5 inhibitor
Sold as: Sold as: Viagra, Revatio, Viagra Connect; Prescription only

From the approved label

Viagra

Approved uses: VIAGRA is a phosphodiesterase-5 (PDE5) inhibitor indicated for the treatment of erectile dysfunction (ED)
Forms and strengths: VIAGRA is supplied as blue, rounded diamond shaped film-coated tablets containing sildenafil citrate equivalent to 25 mg, 50 mg, or 100 mg of sildenafil.
Tablets are debossed with "VIAGRA" on one side and "VGR 25", "VGR 50" or "VGR 100" on the other to indicate the dosage strengths.
Tablets: 25 mg, 50 mg, 100 mg
How it is taken: Based on effectiveness and toleration, may increase to a maximum of 100 mg or decrease to 25 mg
Maximum recommended dosing frequency is once per day Dosage Information For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, VIAGRA may be taken anywhere from 30 minutes to 4 hours before sexual activity. The maximum recommended dosing frequency is once per day.
Must not be used when: Administration of VIAGRA to patients using nitric oxide donors, such as organic nitrates or organic nitrites in any form. VIAGRA was shown to potentiate the hypotensive effect of nitrates
Known hypersensitivity to sildenafil or any component of tablet
Administration with guanylate cyclase (GC) stimulators, such as riociguat Nitrates Consistent with its known effects on the nitric oxide/cGMP pathway, VIAGRA was shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently is therefore...
Interactions: VIAGRA can potentiate the hypotensive effects of nitrates, alpha-blockers, and anti-hypertensives
With concomitant use of alpha-blockers, initiate VIAGRA at 25 mg dose
CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase VIAGRA exposure ▪ Ritonavir: Do not exceed a maximum single dose of 25 mg in a 48 hour period ▪ Erythromycin or strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, saquinavir): Consider a starting dose of 25 mg Nitrates Administration of VIAGRA with nitric oxide donors such as organic nitrates or...
Warnings and precautions: Patients should not use VIAGRA if sexual activity is inadvisable due to cardiovascular status
Patients should seek emergency treatment if an erection lasts >4 hours. Use VIAGRA with caution in patients predisposed to priapism
Patients should stop VIAGRA and seek medical care if a sudden loss of vision occurs in one or both eyes, which could be a sign of non arteritic anterior ischemic optic neuropathy (NAION). VIAGRA should be used with caution, and only when the anticipated benefits outweigh the risks, in patients with a history of NAION. Patients with a "crowded" optic disc may also be at an increased risk of NAION.
Patients should stop VIAGRA and seek prompt medical attention in the event of sudden decrease or loss of hearing
Caution is advised when VIAGRA is co-administered with alpha-blockers or anti-hypertensives. Concomitant use may lead to hypotension
Decreased blood pressure, syncope, and prolonged erection may occur at higher sildenafil exposures. In patients taking strong CYP inhibitors, such as ritonavir, sildenafil exposure is increased. Decrease in VIAGRA dosage is recommended Cardiovascular There is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease.
Common side effects: most common adverse reactions reported in clinical trials (≥ 2%) are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash.
Most common adverse reactions (≥ 2%) include headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness and rash To report SUSPECTED ADVERSE REACTIONS, contact Viatris at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.
Pregnancy: VIAGRA is not indicated for use in females. There are no data with the use of VIAGRA in pregnant women to inform any drug-associated risks for adverse developmental outcomes. Animal reproduction studies conducted with sildenafil did not show adverse developmental outcomes when administered during organogenesis in rats and rabbits at oral doses up to 16 and 32 times, respectively, the maximum recommended human dose (MRHD) of 100 mg/day on a mg/m 2 basis (see Data).
How it acts: The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil enhances the effect of NO by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum.

Label holder:: Viatris Specialty LLC
Label version:: 17 November 2023

This section reports the approved product information. The wording is condensed from the regulator's own summary, and the full document is linked under Sources.

Written by us

How it works

Sildenafil blocks an enzyme called phosphodiesterase type 5, which is what normally ends an erection by breaking down the signalling molecule that keeps blood vessels in the penis relaxed. Blocking it lets that signal last longer. The signal itself is only produced during sexual arousal, which is why the label describes the drug as requiring stimulation to work at all: it extends a response, it does not create one.

Original and generic

The patent expired in Europe in 2013 and in the United States in 2017. Generic sildenafil is sold by dozens of manufacturers and contains the same active substance at the same strengths as the brand, checked against the same standard. In the United Kingdom a 50 mg version is sold in pharmacies without a prescription under the name Viagra Connect after a pharmacist consultation, which is a different legal status from the prescription version.

What it costs

This is the price collapse that makes the category worth understanding. Branded Viagra still sells at a multiple of the generic, while generic sildenafil in European pharmacies costs a small fraction of that per tablet, with the exact figure depending on strength, pack size and country. The active substance is identical, so the difference is entirely brand and packaging.

How to get it legally

Prescription only in the European Union, and prescription only in the US at every strength. The United Kingdom is the exception, where the 50 mg pharmacy version can be bought after speaking to a pharmacist. Elsewhere the legal route without a surgery appointment is an online clinic where a prescriber reviews a questionnaire, and the questions about heart medication are the point of the exercise rather than a formality.

From the approved label

Revatio: approved for

Approved uses: Pediatric Patients (1 to 17 Years Old) REVATIO is indicated in pediatric patients 1 to 17 years old for the treatment of pulmonary arterial hypertension (PAH) (WHO Group I) to improve exercise ability and, in pediatric patients too young to perform standardized exercise testing, pulmonary hemodynamics thought to underlie improvements in exercise.
Adults REVATIO is a phosphodiesterase-5 (PDE-5) inhibitor indicated for the treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) in adults to improve exercise ability and delay clinical worsening.
Forms and strengths: Tablets: 20 mg
For oral suspension: 10 mg/mL (when reconstituted)
Injection: 10 mg/12.5 mL (0.8 mg/mL) in a single-dose vial
How it is taken: Pediatric patients o ≤ 20 kg: 10 mg three times a day o 20 kg to 45 kg: 20 mg three times a day o > 45 kg: 20 mg three times a day. Dose may be increased based on symptoms and tolerability.
Injection (Adults): 10 mg three times a day administered as an intravenous bolus injection. Recommended Dosage in Adults Oral Dosage The recommended dosage of REVATIO is 20 mg three times a day. Dose may be titrated to a maximum of 80 mg three times a day, if required, based on symptoms and tolerability.
Must not be used when: Use with organic nitrates or riociguat.
History of hypersensitivity reaction to sildenafil or any component of the tablet, injection, or oral suspension.
Interactions: Use with strong CYP3A inhibitors: Not recommended.
Concomitant PDE-5 inhibitors: Avoid use with Viagra ® or other PDE-5 inhibitors.
Warnings and precautions: Vasodilation effects may be more common in patients with hypotension or on antihypertensive therapy.
Use in pulmonary veno-occlusive disease (PVOD) may cause pulmonary edema and is not recommended.
Hearing or visual impairment: Seek medical attention if sudden decrease or loss of vision or hearing occurs.
Pulmonary hypertension (PH) secondary to sickle cell disease: REVATIO may cause serious vaso-occlusive crises. Hypotension REVATIO has vasodilatory properties, resulting in mild and transient decreases in blood pressure.
Common side effects: The following serious adverse events are discussed elsewhere in the labeling: • Hypotension • Vision Loss • Hearing Loss • Priapism • Vaso-occlusive Crisis in Patients with Pulmonary Hypertension Secondary to Sickle Cell Disease Adults: Headache, dyspepsia, flushing, pain in limb, myalgia, back pain and diarrhea. Children: Priapism.
Pregnancy: Limited published data from randomized controlled trials, case-controlled trials, and case series do not report a clear association with sildenafil and major birth defects, miscarriage, or adverse maternal or fetal outcomes when sildenafil is used during pregnancy. There are risks to the mother and fetus from untreated pulmonary arterial hypertension (see Clinical Considerations).
How it acts: Sildenafil is an inhibitor of cGMP specific PDE-5 in the smooth muscle of the pulmonary vasculature, where PDE-5 is responsible for degradation of cGMP. Sildenafil, therefore, increases cGMP within pulmonary vascular smooth muscle cells resulting in relaxation. In patients with PAH, this can lead to vasodilation of the pulmonary vascular bed and, to a lesser degree, vasodilatation in the systemic circulation.

Label holder:: Viatris Specialty LLC
Label version:: 18 December 2024

This section reports the approved product information. The wording is condensed from the regulator's own summary, and the full document is linked under Sources.

Comparison

Questions

Is generic sildenafil the same as Viagra?: It contains the same active substance at the same strength, and a generic is approved only after demonstrating that it delivers that substance into the blood in the same way as the original. The tablet colour, shape and inactive ingredients can differ.
Why does the label mention pulmonary hypertension?: The same molecule is approved separately under the name Revatio for pulmonary arterial hypertension, at a lower strength and a different dosing schedule. It is the same substance holding two approvals for two conditions, which is why both labels appear on this page.
What makes nitrates dangerous with it?: Both lower blood pressure through related pathways, and together the drop can be severe. The label lists this as a contraindication rather than a caution, which is the strongest category it has.

Sources

Viagra: prescribing informationDailyMed, US National Library of Medicine. Label version 17 November 2023
Revatio: prescribing informationDailyMed, US National Library of Medicine. Label version 18 December 2024
Drugs@FDA: NDA020895US Food and Drug Administration
Drugs@FDA: NDA203109US Food and Drug Administration
Viagra: EPAR product informationEuropean Medicines Agency