01Why this page starts at 25 mg and 50 mg, not 100 mg
Most men start sildenafil (Viagra) at 50 mg about one hour before sexual activity. The labelled range is 25 to 100 mg, taken not more than once a day. Shop grids that lead with 100 mg are selling a ceiling, not the usual first tablet. This page follows 25-50 mg because that is where the insert actually starts people.
Twenty-five milligrams is not a weaker product. It is the consider-start for older men, hepatic impairment, severe renal impairment, alpha-blockers, and strong CYP3A4 inhibitors. Fifty milligrams is the usual adult start when those rows are clean. One hundred milligrams is the step up after a documented trial, or the step you never take if side effects already dominate at 50.
Dr. Mateo Ruiz reviewed this page on 2026-08-21 against the Pfizer insert and DailyMed. GoodRx ten-count cash is cited for 25 mg and 50 mg only. This site does not fill prescriptions. Corrections: [email protected].
02When tadalafil or vardenafil is the better clock
Need a 36-hour tail and almost no food effect? Tadalafil 10 mg as needed. Need a fast peak and a clean QT list? Vardenafil 20 mg is the ceiling after a 10 mg start. Need untimed weekdays? Daily tadalafil 2.5 or 5 mg.
Failed 50 mg after honest trials can go to 100 mg on the same INN or to a class switch. Failed 100 mg with a clean list is a workup. Nerve injury after prostate surgery does not melt because the tablet is blue.
03One hundred milligrams is a step, not a first night
After a real trial at 50 mg (arousal present, limited alcohol, food handled), the label allows 100 mg. Side effects that already dominate at 50 mg will not improve at 100. A 25 mg start that was never given a clean attempt is not a reason to skip to 100.
Export 100 mg packs, including Fildena, are still sildenafil citrate. They are not a new enzyme story. They are often the wrong first strength. See Fildena 100 mg for the export-name problem and the missing US cash quote.
Blue vision, headache, and flushing can intensify with the step up. That is not proof the lower tablet 'failed'. It is more PDE5 and more PDE6.
| INN / brand | sildenafil / Viagra (Revatio is PAH) |
|---|---|
| US ED tablets | 25, 50, 100 mg |
| Strengths priced here | 25 mg and 50 mg |
| Approval | US 1998 |
04Who the label points toward 25 mg first
Age 65 years and older: consider 25 mg. Hepatic impairment: consider 25 mg. Severe renal impairment (CrCl under 30 mL/min): consider 25 mg. Concomitant alpha-blocker: start 25 mg and stabilize the alpha-blocker first when possible.
Ritonavir and other strong CYP3A4 inhibitors: 25 mg, and not more than once every 48 hours. Moderate inhibitors (erythromycin, ketoconazole at some doses) also pull the start down. A shop 50 mg carton that never asks about HIV therapy is selling a count.
The dose-step note is the place to hold 25 versus 50 without turning the 100 mg carton into a default.
| Situation | Labelled move | Not a shop move |
|---|---|---|
| Usual adult, clean list | 50 mg ~1 h before sex | Jump to 100 mg first night |
| Age ≥65, liver, severe kidney | Consider 25 mg | Same 50 mg 'for everyone' |
| Ritonavir / strong CYP3A4 | 25 mg every 48 h | Stack a second PDE5 |
| Alpha-blocker on board | 25 mg start, stable BP | Two vasodilators as a hack |
05How long 25-50 mg usually helps
Plasma half-life is about four hours. Counselling talk often uses a four-hour working window. That is shorter than tadalafil's 36-hour study row and in the same band as vardenafil for many men. Arousal is still required.
A second tablet the same calendar day is not a rescue. Maximum labelled frequency is once per day. If 50 mg was clean and still weak after two honest attempts, the next talk is 100 mg with the prescriber, or a class switch - not a midnight booster.
Priapism lasting more than four hours is emergency care. So is sudden monocular vision loss or sudden hearing drop. Those rows sit on every sildenafil strength, including 25 mg.
06GoodRx cash for 25 mg x 10 and 50 mg x 10
Generic sildenafil 25 mg x 10 lists at $67.14 average retail and $13.53 with a coupon on the GoodRx board this page cites. Fifty milligrams x 10 lists at $646.10 / $11.35. Ask the pharmacist to price the count on the script. The 100 mg listing is a different NDC and is not the lock here.
This site does not dispense. A prescription still has to name sildenafil 25 mg or 50 mg. Export brands such as Fildena 100 mg are a different page with no invented US cash for that blister.
Generic sildenafil 25 mg and 50 mg are the starting strengths this page follows, October 2026. GoodRx lists 25 mg x 10 at $67.14 / $13.53 and 50 mg x 10 at $646.10 / $11.35. Ask the pharmacist to price the count on the prescription. The 100 mg maximum is in the body. This site does not dispense.
07Nitrates, riociguat, and other hard stops
Organic nitrates and nitric oxide donors in any form are contraindicated. Riociguat is contraindicated. The shared pathway is cGMP. Shop language that softens this to 'heart issues, ask a doctor' is not the insert.
Alpha-blockers add orthostatic hypotension. Start low, separate the timing when the prescriber asks for it, and do not add tadalafil the same night. Guanylate cyclase stimulators stay on the forbidden list even if the sildenafil stamp is 25 mg.
Sickle cell disease, myeloma, leukemia, and penile deformity raise the priapism caution. Recent stroke, unstable angina, and some recent MI rows push the decision to cardiology, not to a coupon.
Stops that survive a 25 mg stamp
- Nitrates and riociguat: contraindicated
- Priapism >4 h: emergency
- NAION or sudden hearing loss: stop, same-day care
- Revatio plus Viagra: two sildenafil plans - do not stack
08High-fat meals move the peak by about an hour
Fasted median Tmax is about 60 minutes, with a dosing window the label describes from 30 minutes to 4 hours. A high-fat meal delayed that peak by about 60 minutes and reduced Cmax by 29 percent. AUC fell about 11 percent. The tablet is late, not cancelled.
Giving up at 40 minutes after a heavy plate writes a false 'generic failed' review. Wait the extra hour, or take 25-50 mg after a lighter meal if the night is timed. Alcohol adds vasodilation on top of the food delay. That stack tells you nothing useful about milligrams.
Tadalafil's food row is almost flat. If every date is a heavy dinner, the tadalafil 10 mg as-needed page may be the kinder class pick. Do not take both INNs the same night to 'cover' a late meal.
Revatio is sildenafil for pulmonary arterial hypertension, three times a day on a different schedule. Adding a Viagra 50 mg on top of Revatio is a second PDE5 exposure. Keep those plans apart.
| Absorption | Median Tmax ~60 min fasted; high-fat +60 min, Cmax −29% |
|---|---|
| Distribution | Volume and protein binding as in the Viagra PI |
| Metabolism | CYP3A4 (major) and CYP2C9; ritonavir caps the dose |
| Excretion | T½ ~4 h; counselling window often ~4 h |
09What 25-50 mg does not settle by itself
Fifty milligrams remains the usual labelled start. Twenty-five is the step-down and the special-population start. Fat costs you about an hour. Nitrates are forbidden. GoodRx 10-count cash is $67.14 / $13.53 at 25 mg and $646.10 / $11.35 at 50 mg.
Dr. Ruiz reviewed this page on 2026-08-21. Drafted from the label, checked against DailyMed, then read by a clinician. No checkout on this domain.