Which column are you actually paying for?
Start with the clock you can live with, not the name you heard first. Cialis, Viagra and Levitra all inhibit PDE5. They do not invent desire. They do not keep an erection after arousal stops. What you pay for, once a prescriber has cleared the class rules, is a different useful window and a different meal penalty.
This sheet locks three labelled options: tadalafil 10-20 mg PRN, sildenafil 50 mg, vardenafil 10-20 mg. Daily tadalafil 2.5-5 mg is a fourth schedule, not a fourth molecule. It belongs on the daily versus on-demand briefing, not as a secret winner here.
If you came looking for 'the best ED pill', stop. Best for whom? A man who eats late and wants a weekend window is not the same reader as a man on sotalol. I will not rank the columns for a stranger.
How long the tablet stays useful
Usefulness outlasts the first hour only if the half-life allows it. Tadalafil's mean terminal half-life is 17.5 hours. That is why a single 10-20 mg dose can still help the next calendar day, and why a nitrate wait of 48 hours is written on Cialis. Sildenafil and its active metabolite have terminal half-lives of about 4 hours. Vardenafil and M1 sit at about 4-5 hours.
A short half-life is not a defect. Some people want the drug gone by morning. Some want one swallow to cover Saturday and Sunday. Those are lifestyle columns, not efficacy trophies. Head-to-head marketing that crowns a 'stronger' pill usually ignores that the three were not designed as interchangeable milligram contests.
Daily 5 mg tadalafil is the other way to stop watching a clock. Steady-state plasma levels arrive within 5 days of once-daily dosing, with about 1.6-fold accumulation versus a single dose. That schedule is a habit, not a PRN bargain. Price it as thirty tablets, not as 'free spontaneity'.
What the clock does after you swallow
| Column | Usual swallow | Peak on an empty stomach | Useful window |
|---|---|---|---|
| Tadalafil 10-20 mg PRN (Cialis) | Before the occasion; peak is later than the other two | 30 min to 6 h (median 2 h) | Up to 36 h after the dose |
| Sildenafil 50 mg (Viagra) | About 1 h before; label range 30 min to 4 h | 30-120 min (median 60 min) | Hours, not a weekend; t1/2 about 4 h |
| Vardenafil 10-20 mg (Levitra) | About 60 min before | 30 min to 2 h (median 60 min) | t1/2 about 4-5 h |
Swallow time is not the same as 'works in thirty minutes' marketing. Tadalafil's peak sits later: Cmax between 30 minutes and 6 hours, median 2 hours. Sildenafil in the fasted state peaks between 30 and 120 minutes, median 60. Vardenafil after a 20 mg fasted dose peaks between 30 minutes and 2 hours, median 60. Those medians look like cousins. The tails do not.
Sildenafil's labelled swallow is about 1 hour before sexual activity, with a permitted band from 30 minutes to 4 hours. Vardenafil's labelled swallow is about 60 minutes before. Tadalafil's as-needed start is 10 mg prior to sexual activity, then 20 mg or 5 mg by effect and tolerability, once a day at most. The Cialis label also says erectile function stayed better than placebo out to 36 hours. That is a coverage claim, not an erection that lasts a day and a half.
When moving sideways is smarter than climbing milligrams
Switch the column if the complaint matches a fingerprint, not if the first night was poorly timed. Back ache that arrives the next day and fits the tadalafil pattern is a reason to talk about sildenafil or vardenafil, not a reason to double 20 mg. A blue tinge that bothers someone on 50-100 mg sildenafil is a reason to look at tadalafil's long window or vardenafil, if QT is clear. A late, flat 50 mg after steak and fries is a reason to reread the food briefing before anyone writes 100 mg.
Age, liver, kidney and CYP3A4 inhibitors change the milligram inside a column. They do not turn a nitrate user into a candidate. They do not erase vardenafil's QT avoid list. Dose cuts live on the individual sheets: tadalafil, sildenafil, vardenafil.
Shared aches, and the two fingerprints that split
Column extras that actually change a pick
- All three: nitrates, nitrites, poppers, riociguat - closed.
- Tadalafil extra: 48 h nitrate wait if emergency nitrate is later required; daily option; BPH 5 mg daily on the Cialis label.
- Sildenafil extra: high-fat Tmax +60 min / Cmax -29%; color tint via PDE6.
- Vardenafil extra: high-fat Cmax -18% to -50%; QT avoid line; start 5 mg if age 65 or older is being considered.
Headache is shared. The rest is not a tie. Flushing, dyspepsia and stuffy nose show up across the class. Tadalafil is the one with a distinctive delayed back or muscle ache: in pharmacology trials it generally started 12 to 24 hours after the dose and typically settled within 48 hours. Sildenafil is the one with a written color-vision story: PDE6 in the retina, blue/green discrimination, peak near peak plasma, more obvious at 100 mg and 200 mg in formal testing.
None of those rows is a reason to skip assessment. Sudden vision or hearing loss, chest pain, or an erection past 4 hours is urgent care, not a forum thread. Alpha-blockers and antihypertensives can stack blood-pressure drops with any column; start low and keep the other drug stable rather than stacking two new hypotensives the same week.
The nitrate rule is shared; the wait is not
| Column | Nitrate / NO-donor rule | If a nitrate is later judged necessary |
|---|---|---|
| Tadalafil | Contraindicated with any organic nitrate | At least 48 h after the last Cialis dose, then only under close monitoring |
| Sildenafil | Contraindicated with nitrates or organic nitrites in any form | Safe interval is unknown; plasma is much lower at 24 h, but that is not a green light |
| Vardenafil | Contraindicated; a safe interval has not been determined | In healthy men, 20 mg then nitroglycerin 24 h later did not show the same potentiation; still contraindicated in anyone who needs nitrates |
Nitrates close every column. Organic nitrates, organic nitrites, recreational amyl or butyl nitrites ('poppers'), and the guanylate-cyclase stimulator riociguat sit on the same forbidden path: more cGMP on a pathway PDE5 inhibitors already protect. Blood pressure can fall hard enough to cause collapse.
If someone later needs nitroglycerin in a life-threatening setting, the labels stop matching. Cialis: at least 48 hours after the last dose, then only with close hemodynamic monitoring. Viagra: it is unknown when nitrates can be safely given; levels at 24 hours are much lower than peak (about 2 ng/mL versus about 440 ng/mL after 100 mg in healthy men), and that is still not permission. Levitra: a suitable interval has not been determined; a 20 mg dose taken 24 hours before nitroglycerin did not show the same potentiation in healthy middle-aged men, and the contraindication still stands for anyone who uses nitrates.
Chest pain after a PDE5 tablet is an emergency, not a reason to self-treat with the spray in the nightstand. If angina is already treated with a nitrate, none of the three columns is open. Sort the heart first.
What a 'comparison cost' search is actually buying
Generic bottles look cheaper until you count failed first nights and unused daily packs. Sildenafil 50 mg is often the lowest cash line because it has been generic longest. That does not make it the cheapest evening if a high-fat dinner wasted the peak and the next tablet is a 100 mg 'just in case'.
Tadalafil 10-20 mg PRN can be fewer swallows per month if occasions are clustered. Daily 5 mg is thirty tablets whether you use the window or not. Vardenafil 10-20 mg sits in the short-acting price band and adds the QT screen some people should have paid for before the first fill.
I will not invent a US pharmacy table. Prices move by pharmacy, coupon and quantity. Read a real cash quote against the column you can actually take. A banned combination at any price is still banned.
Dinner wrecks two peaks, not three
| Column | Label food line | What a high-fat meal does |
|---|---|---|
| Tadalafil 10-20 mg | May be taken without regard to food | No meal adjustment on the Cialis label |
| Sildenafil 50 mg | May be taken with or without food | Mean Tmax delay 60 min; mean Cmax down 29% |
| Vardenafil 10-20 mg | May be taken with or without food | High-fat meals cut Cmax by 18%-50% |
A heavy plate slows two of these tablets and leaves the third alone on the label. Cialis may be taken without regard to food. That is the whole meal sentence. Viagra may be taken with or without food, and then the PK section adds the number people skip: a high-fat meal delays Tmax by a mean 60 minutes and cuts Cmax by a mean 29%. Levitra may also be taken with or without food, and two food-effect studies cut Cmax by 18% to 50% after high-fat meals.
If your evenings start with a late, greasy plate, the 50 mg column and the 10-20 mg vardenafil column can look like 'the tablet failed' when the tablet was only late and flatter. The timing notes for that mistake live in the sildenafil food briefing. Do not treat a delayed peak as proof you need 100 mg on night one.
The QT line that only one column prints
Only vardenafil carries a written QT avoid line of this shape. In 59 healthy men, therapeutic 10 mg and supra-therapeutic 80 mg produced QTc increases similar to moxifloxacin 400 mg. A later study that paired vardenafil with another QT-active drug showed an additive QTc effect. People with congenital long QT, or on Class IA or Class III antiarrhythmics, should avoid the tablet. Named examples on the label: quinidine, procainamide, amiodarone, sotalol.
That is not a trivia footnote. It is why a 'Levitra 10-20 mg is more potent' review that never mentions the ECG is incomplete. The longer caution sits in the vardenafil QT briefing. If the rhythm history is messy and you have not seen the tracing, do not pick this column to save a few milligrams.
No third-party winner
I have not met you, so I will not crown a tablet. If you need a long window and food never cooperates, the 10-20 mg tadalafil column is the one that matches those two facts. If you want a short, cheap evening and can keep the meal light, 50 mg sildenafil is the column that matches those two facts. If both short tablets are in play and the ECG or the antiarrhythmic list is dirty, vardenafil is the column to leave shut.
Bring the nitrate list, the rhythm list, and how often you actually have sex. That is the visit. Dr. Lena Hofer answers the same grid in the consult below. A prescriber who can see you still has to open one column or none.