What is IIEF, and why should I trust a questionnaire over a review thread?
Forum lore is free. IIEF for 50-100 mg was not
Every sildenafil ED room screened out one group before the first tablet: men on nitrates. That exclusion is now the drug's defining safety strike.
Claim: you can read a thread, pick 50 or 100 mg, and call that evidence. Strike it. Combining a nitrate with sildenafil causes a steep, dangerous fall in pressure. That is not a statistical subtlety. It is a pharmacological certainty, and it is an absolute contraindication on every version of the label. Nitroglycerin, isosorbide, recreational poppers - all off the table. The same strike covers the tadalafil fact line and the vardenafil fact line.
Read every efficacy number below with that boundary in place. These results describe people for whom nitrates were never on the table. A comment that 'my uncle stacked them and was fine' is not a trial. It is an anecdote that survived. The rooms paid for the 50-100 mg ladder by keeping that group out. That cost is the first line on the file.
How a private act became a score
Claim: trial success means men felt better. Strike the vagueness. ED rooms use validated instruments with named endpoints. The workhorse is the International Index of Erectile Function, IIEF, especially the erectile-function domain. It scores the ability to get and keep an erection over recent weeks. A rise in that domain is the primary signal the pivotal sildenafil rooms were built to detect. Sildenafil produced clear, dose-related gains on it. That is why 50-100 mg is not a branding choice. It is a measured ladder.
Two diary items backed the questionnaire. Sexual Encounter Profile question 2 asks whether penetration happened. Question 3 asks whether the erection lasted long enough to finish. On top sat a blunt Global Assessment Question: did treatment improve your erections, yes or no. When a domain score, two behavioural items, and a global yes-or-no all move together and beat placebo, the effect is not an artefact of one scale. That is the pattern across thousands of men.
Goldstein and colleagues published the 24-week, 532-man dose-response room in the New England Journal of Medicine in 1998. Improved erections on the global question: 56 percent at 25 mg, 77 percent at 50 mg, 84 percent at 100 mg, against 25 percent on placebo. Those three percentages are why a prescriber still starts most adults at 50 mg and will consider 100 mg if the 50 mg swallow is honest and still thin. Forum lore does not print those percentages. The journal did.
50 mg start, 100 mg ceiling - the trial ladder
Claim: the three ED strengths are interchangeable SKUs. Strike that. The rooms show a real dose response and a real side-effect climb.
| Setting | Dose | Clock | What the rooms said |
|---|---|---|---|
| ED, usual start | 50 mg | ~1 hour before sex, once daily max | Default adult rung; titrate to effect and tolerance |
| ED, step up | 100 mg | ~1 hour before sex, once daily max | Ceiling; larger IIEF/SEP gains, more headache and flush |
| ED, caution start | 25 mg | ~1 hour before sex, once daily max | Age, CYP3A4 blockers, kidney or liver impairment |
| PAH (Revatio) | 20 mg | Three times daily, ~4-6 h apart | SUPER-1: more milligrams did not buy more walk distance |
Usual adult start: 50 mg about an hour before sexual activity. Step to 100 mg if the effect is short and the tablet is tolerated. Step to 25 mg if headache, flushing, or visual shimmer is too much, or if age, organ impairment, or a strong CYP3A4 inhibitor will raise levels. Maximum once a day. That ceiling is not a scold. It tracks a half-life near four hours. Stacking a second 50 or 100 mg tablet inside 24 hours adds risk without adding a useful second peak.
The start moves for specific people. Sildenafil is cleared largely through CYP3A4. Older adults, significant kidney or liver impairment, and anyone on a strong CYP3A4 blocker - ketoconazole, ritonavir, and similar - are told to start at 25 mg because those states raise exposure. That is label arithmetic, not caution theatre. The clock-and-plate version of the same ladder is filed in the practice note. The molecule's full interaction list sits on the sildenafil fact line.
Who sat in the rooms: diabetes, vessels, surgery
The ED program did not recruit one tidy population. Men with erectile dysfunction from diabetes, from vascular disease, from radical prostatectomy, and from causes with no neat organic label were all studied. Sildenafil beat placebo across those groups. Response ran lower in the hardest cases - long-standing diabetes, post-surgical nerve damage - which is context, not a broken tablet. Breadth is part of why the 1998 stamp was issued with confidence.
That breadth is also why a single forum story is a bad guide to a 50-100 mg order. A man with mild, recent ED and a man five years into diabetic neuropathy are not the same trial cell. Both can be offered the drug. They should not be promised the same percentage. The rooms already said that. A prescriber who starts at 50 mg and waits for a handful of honest attempts is following the file, not stalling.
SUPER-1 held the lung dose at 20 mg
The pulmonary use rests on its own pivotal room, SUPER-1 - Sildenafil Use in Pulmonary arterial hypERtension. Randomised, double-blind, placebo-controlled, 12 weeks, patients with PAH. Doses: 20, 40 and 80 mg three times a day. Primary endpoint: change in six-minute walk distance, a standard measure of exercise capacity in this disease and a reasonable proxy for daily life.
All three doses improved walk distance against placebo. They also improved pulmonary artery pressures on catheterisation and functional class. The finding that still governs the label: the lowest dose delivered most of the benefit. Galie and colleagues reported walk-distance gains in the mid-40-to-50-metre range across 20, 40 and 80 mg TID, a flat dose-effect on the primary endpoint. Higher doses mainly added side effects. That is why approved Revatio is 20 mg three times daily and not a 50-100 mg ED diamond split into thirds.
Carry the contrast. For erectile dysfunction, sildenafil is an as-needed drug pushed toward 50 or 100 mg for effect. For pulmonary hypertension it is a scheduled drug held deliberately low. Same citrate. Opposite dosing philosophy. Each backed by its own rooms. Nitrates remain a hard no in both files.
What the safety sheets actually logged
Common effects tracked the mechanism. Headache, facial flushing, indigestion, nasal congestion - vessels relaxing in places besides the intended bed, more often at 100 mg than at 50. A subset reported visual changes: a transient bluish tinge or extra light sensitivity, from a mild incidental touch on PDE6 in the retina. Generally mild. Short-lived. Not the rare events people conflate with them.
The rooms and later reports also mapped the rails that matter more than the nuisances. Beyond the nitrate strike: caution with alpha-blockers used for pressure or prostate symptoms, because the combination can drop pressure too far. Rare but serious: sudden vision loss from non-arteritic anterior ischaemic optic neuropathy, and sudden hearing loss, sometimes with ringing and dizziness. Those warrant stopping the tablet and seeking care. The regulator's summary sits at the FDA. None of this reversed the core verdict - effective, generally tolerated - but it set the rails a 50-100 mg prescription still runs on.
Class cousins differ on clock, not on the nitrate strike
Claim: all PDE5 pills are the same except the brand. Strike that. Timing, food sensitivity, and side-effect flavour differ in ways the rooms and the pharmacology make clear.
| Feature | Sildenafil 50-100 mg | Tadalafil | Vardenafil |
|---|---|---|---|
| Onset | ~30-60 min | ~30-45 min | ~30-60 min |
| Half-life | ~4 hours | ~17.5 hours | ~4-5 hours |
| Useful window | ~4 hours | Up to ~36 hours | ~4-5 hours |
| Food | Fatty meal delays and lowers peak | Minimal | Fatty meal delays peak |
| Usual style | As needed, 50 or 100 mg | As needed or low daily | As needed |
| Nitrates | Hard no | Hard no | Hard no |
All three share the mechanism and the nitrate strike, so the choice is not 'which one works.' It is which clock and which plate you can live with. Sildenafil and vardenafil behave similarly: onset in roughly half an hour to an hour, a useful window of a handful of hours, both blunted by a fatty meal. Tadalafil is the outlier, half-life around 17 to 18 hours, a window that can stretch toward 36 hours, or a low daily dose, and much less food sensitivity. Deeper profiles live on the tadalafil fact line and the vardenafil fact line.
File the numbers. Leave the thread.
Put together, the rooms tell a consistent story. Sildenafil improves erectile function across most causes of ED, in a dose-related way, on instruments built for the job. It improves walk distance in PAH at a modest scheduled dose. Neither result is inflated. The ED effect is real and still needs stimulation. It does less in the hardest cases. The PAH effect is meaningful and is one tool among several for a serious disease, not a cure.
The evidence also draws its own limits, which is a mark in its favour. Dose ceilings, lower starts for older adults and CYP3A4 interactions, eye and ear cautions, and the nitrate ban are in the data and the label, not bolted on by a later scare. A drug this well studied leaves little room for guessing. Match 50 or 100 mg to the person, respect the exclusions, and the rooms say the tablet does what it claims. How that translates into an evening is filed in the clock-and-plate note. How the molecule even had a file to study is in the Sandwich angina file. Bring any dose change to a clinician who has your list before you copy a thread.
Reader mail
Reader questions on this article
Answered by Dr. Priya Anand, MD · Urology & men's health
Readers treat forum lore as a second label. Here is what the 50-100 mg rooms actually paid for.
The International Index of Erectile Function is a validated instrument. Its erectile-function domain asks about getting and keeping an erection over recent weeks. A rise in that score is what the pivotal sildenafil rooms were built to detect. We cannot run a fair drug trial on vibes. A validated tool has been checked to measure what it claims and to give consistent results. When 50-100 mg beats placebo on IIEF and also on SEP2, SEP3, and a global yes-or-no, the effect is real. A thread is one person's Tuesday. IIEF is how a private act became a number a regulator could stamp. That is the cost of proof. Forum lore is free because it skipped that cost.
How does a doctor pick between 50 mg and 100 mg if both are 'the' dose?
Start in the middle and move. Standard adult start is 50 mg about an hour before sex. Move to 100 mg if an honest 50 mg swallow - empty-ish stomach, real stimulation, enough lead time - is still thin. Move to 25 mg if side effects are loud, or if age, kidney or liver impairment, or a CYP3A4 blocker will raise levels. The rooms showed a genuine dose response: more milligrams, more IIEF and SEP movement, more headache and flush. Once a day is the hard cap. Beyond that it is tuning, not a ranking of which tablet is 'stronger' in a cart. I do not start everyone at 100 mg to 'make sure.' That is how you buy side effects you did not need.
What was SUPER-1, and why do you refuse to treat 20 mg as a cheap ED bargain?
SUPER-1 was the pivotal PAH room: 12 weeks, 20 versus 40 versus 80 mg three times a day versus placebo, six-minute walk as the main endpoint. The lowest dose delivered most of the walk-distance gain. Higher doses mainly added adverse effects. That is why Revatio is 20 mg TID and not a 50-100 mg ED diamond split up. It is also why I strike the idea of using leftover lung tablets as a bargain ED supply, or the reverse. Different disease, different clock, different proof. MedlinePlus keeps an accessible overview at MedlinePlus.
The three PDE5 drugs look identical in reviews. Is there a real reason to prefer 50-100 mg sildenafil?
They share a mechanism and the nitrate strike, so none is 'safer' on that count. They differ on clock and plate. Sildenafil and vardenafil: half an hour to an hour, a few useful hours, both slowed by a heavy fatty meal. Tadalafil: half-life near 17 to 18 hours, a window that can stretch toward a day and a half, or a low daily dose, much less food fuss. Prefer 50-100 mg sildenafil if you want a short, on-demand window and you can keep dinner from sitting on the tablet. Prefer tadalafil if planning around a plate and a clock is the problem. Compare them on the tadalafil fact line and the vardenafil fact line.
Why can't I take 50 mg on a day I also need my nitrate spray if I leave a few hours?
Because that pair can drop pressure to a dangerous level, and there is no home-made gap that makes it safe. Both relax vessels through the same cyclic GMP path, from different ends. Together the effect stacks. Fainting, heart attack, death - those are the words on the file, not a scare poster. Absolute contraindication means never, not a risk to balance on a calendar. If you rely on a nitrate for angina, sildenafil is off the table, including poppers. Tell whoever might prescribe a 50-100 mg tablet about the nitrate, and tell your heart clinician if an ED drug is suggested. The FDA is explicit at the FDA.
Six-minute walk distance for a lung trial sounds crude. Why was that the proof?
Simple is not crude. In PAH, how far someone can walk in six minutes captures the thing patients care about: capacity for ordinary physical work. It also correlates with how the disease is treating them. SUPER-1 used it as the primary endpoint and backed it with catheter pressures and functional class. When a walking test, an invasive pressure, and a clinical rating all move together, the result is trustworthy. Fancy endpoints are not always better. A measure that reflects real function and can be repeated across centres has advantages a biomarker alone does not. That walk-distance file is why 20 mg TID stuck and 80 mg TID did not.
I read 100 mg can wreck vision or hearing. Should that keep me from a trial-backed dose?
It should inform you, not frighten you off a 50-100 mg prescription that otherwise fits. The common visual effect and the rare serious ones are different files. Many men notice a mild, temporary bluish tint or extra light sensitivity from a minor PDE6 touch. That fades as the drug clears. Separately, and rarely, there are reports of sudden vision loss from an optic-nerve event, and sudden hearing loss, sometimes with ringing and dizziness. Uncommon. If either happens, stop the tablet and get seen. For most people the drug is tolerated. Knowing the warning signs is what lets you use the dose the rooms actually supported. Mayo Clinic summarises this at Mayo Clinic.
Do I need to 'buy extra proof' with 100 mg if 50 mg already beat placebo in Goldstein?
No. 50 mg already beat placebo on the global question - 77 percent versus 25 percent in that 24-week room. 100 mg added more responders and more adverse effects. Extra milligrams are a titration, not a second purchase of legitimacy. If 50 mg works and you feel well, staying there is following the file. Stepping to 100 mg is for an honest miss at 50, not for a sense that a higher SKU is more 'real.' I see men order 100 mg first because a thread said 50 is 'weak.' That is forum lore pricing a tablet the rooms already priced.
If I order generic 50-100 mg, did I skip the trial cost because the brand already paid it?
You skipped the brand premium. You did not skip the label. A licensed generic has to match the citrate and the strength. It inherits the same IIEF-backed ladder, the same once-daily cap, the same nitrate strike, the same food delay. The cost of proof was paid in the 1990s rooms. A cheaper bottle does not reopen those rooms and does not erase them. What a cheap cart outside a pharmacy can skip is quality. That is a different risk. Get 50 or 100 mg through a real pharmacy. The current teaching file is the sildenafil fact line.
General education from a clinician, not personal medical advice. Bring your own history to your own prescriber.
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