01 Two clocks bound on one page, not a brand contest
Cialis and Viagra share PDE5 and then part ways on the hour you swallow. This sheet keeps three labelled moves: tadalafil 2.5 mg at a fixed morning, tadalafil 10 mg before a planned evening, and sildenafil 50 mg or 100 mg after you decide what is on the plate.
Full leaves sit elsewhere. The tadalafil 2.5-10 mg leaf owns the 17.5-hour half-life and the 48-hour nitrate hold. The sildenafil 50-100 mg leaf owns the high-fat delay. The vardenafil 20 mg leaf is the fast-peak third line, not the title pair.
Do not take two PDE5 tablets on the same day to 'cover gaps.' Once-daily frequency is already the cap on each insert. Combining Cialis and Viagra is a duplicate pathway, not a clever overlay.
Mail about wording: [email protected]. Virena does not write the order.
02 Dinner moves Viagra; it barely touches Cialis
Dinner moves Viagra; it barely touches Cialis. Tadalafil's rate and extent of absorption are not influenced by food. Sildenafil may be taken with or without food, then pays a mean 60-minute Tmax delay and a 29% Cmax cut after a high-fat meal.
That is the whole food argument. It is not 'never eat with Viagra.' It is 'if you want the median hour, do not park 50 mg on a heavy plate.' One hundred milligrams after the same plate still pays the delay.
Tadalafil's sharper meal-adjacent warning is alcohol: five units or more can add a standing-pressure drop. Sildenafil 50 mg with 0.5 g/kg alcohol (mean 0.08%) did not add a hypotensive interaction in healthy men; 100 mg was not in that design.
A long Bordeaux dinner with five glasses plus tadalafil 10 mg is the Cialis alcohol line. The same dinner plus sildenafil 50 mg is mostly a late, lower peak plus ordinary wine effects. Neither sentence is a drinking plan.
| Clock | Food | Lead | Leftover |
|---|---|---|---|
| Tadalafil 2.5 mg daily | No change | Same hour each day | Steady level; 48 h nitrate hold |
| Tadalafil 10 mg PRN | No change | Before anticipated activity; median Tmax ~2 h | Labelled attempts to 36 h |
| Sildenafil 50-100 mg | High-fat: +60 min Tmax, -29% Cmax | About 1 h (30 min to 4 h) | Effect fading by 4 h |
03 Forty-eight hours versus twenty-four on the nitrate line
Forty-eight hours versus twenty-four on the nitrate line is not a branding detail. Tadalafil's mean half-life is 17.5 hours. Lilly's daily 20 mg plus nitroglycerin study still showed a blood-pressure interaction through 24 hours; at 48 hours most measures had settled. The hold is two days, then only with monitoring if a nitrate is required in a crisis.
Sildenafil's half-life is about 4 hours. After 100 mg, healthy-volunteer plasma at 24 hours is about 2 ng/mL versus a peak near 440 ng/mL. Pfizer still writes that it is unknown whether a nitrate is safe at that hour, and leftovers are higher in older, hepatic, renal, or CYP-inhibited patients. This sheet uses 24 hours as the practical sildenafil interval and keeps that caveat.
Both INNs are contraindicated with any organic nitrate and with riociguat. Poppers count. Chest pain after either tablet is emergency care with the last dose time, not a home spray.
Vardenafil 20 mg, if it enters the same visit, used a 24-hour healthy-volunteer gap before extra nitroglycerin effects disappeared, and still forbids the combination. QT screening is extra work that Cialis and Viagra do not copy in the same words.
04 A 2.5 mg morning versus a same-night 50 mg hour
A 2.5 mg morning versus a same-night 50 mg hour is the first real choice. Daily tadalafil is swallowed because the hour of the day arrived. Sildenafil 50 mg is swallowed because an attempt is likely in about 60 minutes (or 30 minutes to 4 hours).
Couples who refuse a countdown often keep daily 2.5 mg, or the labelled rise to 5 mg, and stop negotiating lead time. Couples who want a tablet only on nights that happen keep 50 mg and accept the lead. Neither choice is more 'natural.' They are different labelled designs.
If the household already eats late and heavy, daily tadalafil avoids the sildenafil food fight. If the household wants a same-evening peak and rarely drinks five units, 50 mg after a lighter plate is the tighter clock.
Do not run 2.5 mg every morning and add 50 mg on Friday. That is two PDE5 exposures. Pick one clock with the clinician.
Three clocks this sheet will keep comparing
05 Quoted boards for the two title clocks
Quoted boards for the two title clocks sit on the tadalafil and sildenafil leaves. This sheet reprints the daily 2.5 mg thirty-count band so the morning habit has a sourced row. The 50 mg and 100 mg ten-counts live on the Viagra leaf quote strip.
Virena does not dispense. GoodRx figures are captions, not French till prices.
Generic tadalafil 2.5 mg x 30, GoodRx Cialis daily table.
Generic tadalafil 2.5 mg, thirty tablets, the Virena daily leaf lock, August 2026. GoodRx lists 2.5 mg x 30 at $313.08 average retail and $16.93 with a coupon. Ten-milligram PRN packs are a separate row on the same table. Virena does not dispense.
06 Ten milligrams of tadalafil that still owns Sunday
Ten milligrams of tadalafil that still owns Sunday is the PRN Cialis clock. Labelled erectile function versus placebo holds out to 36 hours. Timed-attempt work at 24 and 36 hours (10 mg and 20 mg) stayed above placebo at both marks. Saturday 18:00 can still be a Sunday attempt without a second tablet.
Sildenafil does not reprint that weekend. RigiScan effect was shown to 4 hours and was already weaker than at 2 hours. A Saturday 50 mg is not a Sunday leftover plan. If Sunday matters as its own night, either take a new sildenafil the next day (once daily still) or use tadalafil's longer window.
The 36-hour leftover is also why tadalafil's nitrate hold is 48 hours. You cannot have a quiet Sunday nitrate if Saturday's 10 mg is still in the story. Sildenafil's practical hold is 24 hours, with the Viagra insert still saying safety at that hour is not established.
Weekend walk-throughs without repeating this sheet live on the two-evening 10 mg margin and the daily 2.5 versus 10 mg ink.
07 Where 20 mg vardenafil sits without stealing the title
Where 20 mg vardenafil sits without stealing the title: fasted median Tmax 60 minutes, half-life 4-5 hours, high-fat Cmax cut 18% to 50%, QT caution, start usually 10 mg. It is a same-night peak tablet with extra ECG homework.
Choose it when a supervised 10 mg hour was weak and QT drugs are absent. Do not choose it to invent a third weekend. It will not give tadalafil's 36 hours.
Do not combine it with Cialis or Viagra. The 20 mg vardenafil leaf and the QT margin keep those details off this title pair.
Export combos that stack sildenafil with tadalafil in one blister are not a US NDC on this sheet. They are not a way to bind the two clocks.
- Need a tablet that ignores dinner and can cover Sunday: tadalafil 10 mg PRN, or daily 2.5 mg if midweek matters
- Need a same-night hour and will manage the plate: sildenafil 50 mg, 100 mg if a fair 50 mg failed
- Need a fast peak and a QT screen is already clean: vardenafil 20 mg after a 10 mg trial
- Need a nitrate in weekly use: none of these tablets belong on the chart
08 Inhibitors rewrite both clocks before brand preference does
Inhibitors rewrite both clocks before brand preference does. Ketoconazole or ritonavir with tadalafil caps as-needed use at 10 mg every 72 hours and daily use at 2.5 mg. The same inhibitors with sildenafil often start the night at 25 mg, and ritonavir can hold a 25 mg interval out to 48 hours after an 11-fold AUC jump.
Rifampin shrinks tadalafil (10 mg AUC minus 88%) and is expected to shrink sildenafil at least as hard as bosentan did (AUC minus 63% in a PAH-dose study). A 'stronger brand' does not restore that exposure. Do not add a second INN to chase a ghost dose.
Renal cuts differ in the details. Tadalafil PRN in moderate impairment starts at 5 mg and caps 10 mg every 48 hours; severe disease or hemodialysis is 5 mg every 72 hours on labelled PRN rows. Sildenafil's numbered double exposure is the severe band (Clcr under 30 mL/min), with a 25 mg start. Mild and moderate sildenafil impairment did not change a 50 mg volunteer dose.
Age 65 and over is a 25 mg consideration on Viagra and a 25% higher tadalafil AUC without an automatic milligram cut. Vardenafil in the same age band often starts at 5 mg because Cmax and AUC were 34% and 52% higher. Those three elderly sentences are not interchangeable.
If the visit is really about a weekly nitrate spray, none of the three clocks belong on the chart. A clean CYP list does not open a contraindicated nitrate pair.
09 Choose a clock in clinic, not a slogan on a box
Choose a clock in clinic, not a slogan on a box. Bring the nitrate list, the dinner habit, and whether Sunday leftover matters. Those three facts pick 2.5 mg daily, 10 mg PRN, or 50-100 mg after food faster than a brand preference. If a weekly nitrate spray is already in the coat, none of the three clocks belong on the chart, and a clean CYP list does not reopen them. Elise dated the binding on 21 August 2026. Do not take Cialis and Viagra on the same calendar day to cover a gap.
Elise Moreau reviewed this binding on 21 August 2026. Change INN only with the clinician who has the rest of the chart.
| Title pair | Cialis (tadalafil) vs Viagra (sildenafil) |
|---|---|
| Third clock | Levitra 20 mg, QT first |
| Virena tadalafil lock | 2.5 mg daily or 10 mg PRN |
| Virena sildenafil lock | 50 mg and/or 100 mg after food |
| Nitrate holds | 48 h tadalafil; 24 h sildenafil / vardenafil |