Sildenafil: Generic Viagra, How Long and Uses

Generic Viagra is the same citrate

Generic Viagra is sildenafil citrate in the same 25, 50, and 100 mg oral tablets as the brand. FDA's generic questions page says an approved generic has to match the brand in dosage form, strength, route, and how it performs. Teva's ANDA 077342 was approved for those three strengths as bioequivalent and therapeutically equivalent to Pfizer Ireland's Viagra tablets.

Pfizer's brand is a blue rounded diamond with PFIZER on one face and VGR25, VGR50, or VGR100 on the other. One generic USP tablet in DailyMed is a blue round biconvex film-coated tablet debossed 86, 87, or 88. GoodRx's generic explainer says many sildenafil tablets are small and white. Inactive ingredients can differ. The citrate milligram does not.

How long the labelled window lasts

The US patient leaflet for Viagra says beginning in about 30 minutes and for up to 4 hours, the tablet can help if the man is sexually excited. Both sildenafil and its N-desmethyl metabolite have terminal half-lives of about 4 hours. Mayo Clinic writes that action is usually less after 2 hours.

A four-way crossover in 16 men (mean age 55) gave 100 mg or placebo 1, 8, or 12 hours before visual sexual stimulation. Mean RigiScan time at ≥60% rigidity was 26, 11, and 8 minutes at those hours, against 3 minutes after placebo. Of the men who responded at 1 hour, 82% still responded at 8 hours and 45% at 12 hours.

How long it takes to work

Maximum plasma levels sit between 30 and 120 minutes after a fasted dose, median 60 minutes. Absolute bioavailability is 41% (range 25–63%).

A 50 mg onset study put median time to erection at 27 minutes (range 12 to 70). Seventy-one percent had onset by 30 minutes, and 82% by 45 minutes. The earliest recorded onset was 12 minutes.

A high-fat meal delayed Tmax by a mean 60 minutes and cut Cmax by 29%. The US leaflet uses a cheeseburger and french fries as that meal. The peak arrives later.

What sildenafil is used for

Sildenafil tablets for erectile dysfunction raise blood flow in the penis when nitric oxide is already being released. There is no erection from the tablet alone.

The same INN is sold as Revatio and Liqrev for pulmonary arterial hypertension, to improve exercise ability. Revatio tablets start at 20 mg every eight hours. Viagra 25, 50, and 100 mg and Revatio are not interchangeable. The PAH carton says not to take Viagra or another PDE5 inhibitor during that treatment. FDA approved the ED tablet on 27 March 1998.

Where a US pharmacy fills it

Ro, Hims, Healthline, and the Viagra site all put the same gate on a US fill: a licensed clinician writes a prescription, then a pharmacy dispenses 25, 50, or 100 mg. The visit can be in a clinic or on a telehealth service that actually examines the history. After that, the script can sit at a local counter or at a licensed mail pharmacy.

FDA's BeSafeRx page is the check for whether an online pharmacy is licensed in the state that receives the bottle.

Viagra Connect on a UK pharmacy shelf

Sildenafil for erectile dysfunction stays prescription-only in the United States. The OTC leftover on this query is the UK product. MHRA reclassified Viagra Connect from POM to a pharmacy (P) medicine: 50 mg sildenafil, men 18 and older with erectile dysfunction, supplied by or under a pharmacist after a suitability check.

The UK SmPC dose is one 50 mg tablet with water about one hour before sex, once per day. The first pharmacy pack was capped at eight tablets. Men already on a different sildenafil strength, or on another ED tablet, are referred back to a doctor. That shelf is not a US drugstore aisle.

The 50 mg start, then 25 or 100

For most patients the recommended dose is 50 mg as needed, about one hour before sexual activity, or anywhere from 30 minutes to 4 hours. The ceiling is 100 mg. The frequency ceiling is once per day.

The dose can be cut to 25 mg when side effects sit too high, when an alpha-blocker is already on board, when a strong CYP3A4 inhibitor is in the list, or when clearance is reduced (severe renal impairment, hepatic impairment). UK SmPC text says a 65-and-over man does not need an automatic cut; the US leaflet still lets the prescriber start lower when AUC is expected to rise.

A second tablet the same day is not the labelled next step. UK SmPC notes that studied doses above 100 mg did not raise efficacy; adverse reactions increased.

Side effects in the ≥2% table

The US adverse-reaction table (≥2%) on fixed-dose trials lists headache at 16% on 25 mg, 21% on 50 mg, and 28% on 100 mg, against 7% on placebo. Flushing was 10%, 19%, and 18% against 2%. Dyspepsia reached 17% on 100 mg. Abnormal vision, including a blue tinge or blur, was 11% on 100 mg and 1% on placebo. Nasal congestion, back pain, myalgia, nausea, dizziness, and rash fill the rest of that table.

Priapism is the 4-hour erection that needs emergency care. Sudden vision loss in one or both eyes can be NAION; the leaflet says stop the tablet and call. Sudden hearing loss, sometimes with tinnitus or dizziness, has the same stop. Heart attack, stroke, irregular beats, and death have been reported rarely; most of those men already had heart disease. The leaflet says it is not known whether the tablet caused those events.

Nitrates and the blood-pressure drop

Nitrates for chest pain — tablets, patches, sprays, ointments, isosorbide dinitrate or mononitrate, nitroglycerin — drop blood pressure to an unsafe level when they sit with sildenafil. Recreational nitrites (“poppers”) sit in the same stop. Riociguat is also listed. The Pfizer patient leaflet puts fainting, heart attack, or stroke on that combination. The heart guide keeps the 24-hour Princeton wait and the sex-after-MI clocks.

Viagra for women

The Viagra carton is not indicated for use by females. Cleveland Clinic, Drugs.com, and Mayo all repeat that FDA has not approved the ED tablet for women's sexual dysfunction. Small trials in women have been inconsistent. The tablet does not treat low desire.

Addyi (flibanserin) 100 mg at bedtime is indicated for women under 65 with acquired, generalized hypoactive sexual desire disorder; the December 2025 FDA label is the current sheet. Vyleesi (bremelanotide) is a premenopausal HSDD injection.

Cocaine and sildenafil case reports

The US sildenafil tablet label does not give cocaine its own interaction row. Metabolism of the tablet is mainly CYP3A4. Liverpool's chemsex sheet calls cocaine a minor CYP3A4 inhibitor and rates a predictable pharmacokinetic clash as low.

Published leftover is case reports: a middle-aged man with no prior angina had a non-ST-elevation myocardial infarction after cocaine, alcohol, sildenafil, and intercourse (PubMed 21796081). A 2001 Journal of Emergency Medicine letter described acute aortic dissection after cocaine and sildenafil. Cocaine itself raises heart rate and blood pressure.

DEA schedule on the carton

DailyMed's product header for sildenafil citrate tablets lists DEA Schedule: None. The Greenstone authorized-generic carton (NDC 59762-0034 and the 50 mg and 100 mg siblings) leaves the DEA Schedule field blank and prints Rx only. Sildenafil is not named in the CSA schedules at 21 U.S.C. § 812. A US fill still needs a prescription.

Sildenafil versus tadalafil

GoodRx and Medical News Today treat the pair as the two common PDE5 starts; the Cialis vs Viagra split lives on the comparison guide. The Cialis US label gives as-needed tadalafil a start of 10 mg, then 20 mg or 5 mg, with erectile function improved versus placebo up to 36 hours. Once-daily Cialis is 2.5 mg, or 5 mg, taken without regard to the hour of sex and without regard to food. Cialis also carries BPH and ED/BPH lines.

Sildenafil's labelled ED window is 30 minutes to 4 hours, with a high-fat meal delaying Tmax about 60 minutes. There is no daily ED carton and no BPH indication on the Viagra sheet. Both labels keep the nitrate stop. The Cialis sheet says not to combine Cialis with another PDE5 inhibitor.

Updated: 11 November 2026, 03:00:47 UTC