Sildenafil or Tadalafil: Which One Suits You Better

Neither is better. They are two licensed medicines in the same class that behave differently, and the useful question is which one fits your circumstances rather than which one wins.

The difference that matters most is time. Sildenafil at the standard strength was effective from less than 1 hour to up to 4 hours after the dose. Tadalafil tablets may still be effective up to 36 hours after taking the tablet. That is not a small gap, and it changes what each medicine is practically useful for.

There is a second thing worth knowing before you read any comparison page, including this one. There is no head-to-head trial in the material reviewed for this page. The figures for each medicine come from separate studies, in separate populations, measuring separate endpoints. Setting them side by side is useful for understanding how each behaves. It is not a controlled comparison, and any page presenting it as one is overstating what the evidence supports.

So this page compares what is documented for each, keeps the two sets of figures clearly attributed, and is explicit about the questions the evidence does not answer.

Key things to know

• Sildenafil's documented window runs from less than 1 hour to up to 4 hours after the dose
• Tadalafil may still be effective up to 36 hours after the tablet is taken
• Tadalafil comes in two formats, on demand and a low strength taken daily. Sildenafil is on demand only
• Food matters for sildenafil and its effect is documented. A meal delays peak concentration by around 60 minutes and reduces it by around 29%
• Neither is a stimulant. Both need arousal to do anything, and neither increases desire
• Never take both together. They are the same class and the blood pressure effects add up
• Neither should be taken more than once a day, or at a higher dose than prescribed
• Nitrates must not be used with either medicine. Because tadalafil can remain active for longer, the product information states that in a life-threatening situation nitrates may be considered only after at least 48 hours and under close medical supervision
• Both can interact with nitrates and alpha blockers, so a prescriber must review your complete list of other medicines
• Neither cures erectile dysfunction. Both help manage the symptoms
• Treatment suitability depends on an individual clinical assessment

The Difference Between Them

What They Have in Common

Both are phosphodiesterase type 5 inhibitors, usually shortened to PDE5 inhibitors. Both are licensed in the UK for erectile dysfunction in adult men aged 18 and over. Both work the same way at the molecular level, by preventing the breakdown of a messenger called cGMP so that blood vessels relax and blood flow can increase.

Both share the critical safety exclusions. Nitrates and nitric oxide donors are an absolute contraindication for either, as is riociguat.

Both also have important cardiovascular contraindications, including use in people for whom sexual activity is inadvisable. The exact contraindications and time periods differ between the two, so cardiovascular suitability should be assessed individually before treatment.

And both are conditional. Neither creates arousal, and neither does anything without it. A tablet of either sitting in your system produces no effect by itself.

That shared foundation is why the choice between them is rarely about safety and almost always about timing and fit.

Duration

This is the headline difference and the reason most people comparing the two end up choosing one over the other.

Sildenafil. The documented statement is that sildenafil at the standard strength was effective at various times post dose, from less than 1 hour to up to 4 hours after administration. Its terminal phase half-life is 3 to 5 hours.

Tadalafil. The documented statement is that tadalafil tablets may still be effective up to 36 hours after taking the tablet.

Four hours against thirty-six. In practical terms, sildenafil suits a planned occasion. Tadalafil suits a period rather than a moment, which is why it is sometimes described as covering a weekend rather than an evening.

Neither figure is a promise. Both describe a window in which the medicine can be expected to help rather than an assurance that it will, and results vary between individuals.

Onset

The two are closer here than the duration figures suggest.

Sildenafil reaches peak plasma concentrations within 30 to 120 minutes, with a median of 60 minutes, and was documented as effective from less than an hour after the dose.

For tadalafil, the documented guidance is that the tablet may be taken at least 30 minutes beforehand.

Both can begin to work relatively soon after dosing, although the evidence and timing measures are not directly comparable between the two. The difference is at the other end: sildenafil's window closes, and tadalafil's stays open considerably longer.

The Two Side by Side

A note on the blank. One cell says the figure is not quoted. That is deliberate. It was not verifiable from UK regulator sources within the material reviewed for this page, and filling it in with a number from elsewhere, or worse with sildenafil's number, is exactly the error that makes most comparison pages unreliable. Where a figure is not here, it is because it was not confirmed.

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Which Is Better?

Why There Is No Head-to-Head Answer

The honest position is that no comparison trial appears in the material reviewed for this page, so no evidence-based statement that one outperforms the other is available to make.

That is not a technicality. Two medicines studied separately, in different trial populations, with different entry criteria and different outcome measures, cannot be ranked by putting their results in adjacent columns. Differences in the populations alone can produce a gap that has nothing to do with the medicines.

What can be said is that they differ in ways that are documented and that genuinely matter to how each one fits into a life. That is a more useful basis for choosing than a false ranking.

How to Choose Between Them

Work through the circumstances rather than the medicines. These are the questions a prescriber will be weighing, and thinking about them in advance makes the consultation more useful.

1. How predictable is your timing? If occasions are planned, a shorter window is not a limitation. If they are not, a longer one removes the need to plan
2. How often are you likely to need it? Occasional use points one way. Frequent use raises the daily format as a genuinely different option
3. How do you feel about a tablet being in your system for longer? Some people find that reassuring. Others prefer something that clears
4. What else are you taking? The exclusions are shared, but individual interactions still need checking against your own list
5. How do you respond? Nobody knows this before trying, and the answer usually settles the question better than any comparison table

The last point deserves weight. Individual response varies, and someone who does not get on with one PDE5 inhibitor may do well on another. That is a clinical conversation rather than something to decide from a page. Your prescriber will determine the appropriate treatment.

The Daily Option

This is a genuine structural difference rather than a matter of degree, and it is the one most often missed.

Sildenafil is an on demand medicine. It is taken when needed, and the maximum recommended dosing frequency is once per day. There is no licensed daily sildenafil format for erectile dysfunction.

Tadalafil exists in both formats. There is an on demand tablet, and there is a separate lower strength tablet taken daily. Tadalafil daily is a different product from the on demand version, not the same tablet taken more often.

The practical distinction is about planning rather than potency. On demand means deciding in advance that you will want the medicine. Daily use removes that decision, because the medicine is already present.

Which is appropriate depends on how often treatment is needed and on the clinical picture, and it is a prescriber decision rather than a preference to be selected at checkout. Never adapt an on demand tablet into a daily routine on your own.

Effectiveness

For sildenafil, the documented figures come from fixed dose studies, where the proportions of patients reporting that treatment improved their erections were 62% at the lowest strength, 74% at the standard strength and 82% at the highest, compared with 25% on placebo.

Those figures belong to sildenafil. They are not tadalafil's figures and must not be read as such.

No comparable verified figure for tadalafil, and no head-to-head comparison, was available for this page. So the honest answer to which is more effective is that the evidence reviewed here does not support ranking them.

Two things are worth adding, because they matter more than a percentage.

Effectiveness is individual. Group percentages describe populations. Your response is a sample of one, and it is the only figure that will actually affect you.

First attempts mislead. In the sildenafil studies, 40.8% of men on the standard strength reported improvement after the first dose, but across repeated attempts up to eight doses that rose to 78.4%. Judging any of these medicines on one occasion is unreliable.

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Practical Differences Day to Day

With Food

For sildenafil the food effect is documented and specific. When taken with food, the rate of absorption is reduced, with a mean delay in time to peak concentration of 60 minutes and a mean reduction in peak concentration of 29%.

That does not make sildenafil ineffective after a meal. It shifts the peak later and lowers it, which can make the useful part of the window feel narrower than expected after a heavy dinner.

Food does not have a clinically relevant effect on tadalafil absorption, so tadalafil can be taken with or without food. The leaflet supplied with your pack is the authoritative source for that product.

One instruction applies to both and is worth repeating. Grapefruit and grapefruit juice are documented as able to affect how sildenafil works, because grapefruit juice inhibits the enzyme that clears it.

With Alcohol

The documented alcohol finding for sildenafil is specific and reassuring at moderate levels. Sildenafil did not worsen the blood-pressure-lowering effect of alcohol in healthy volunteers with mean maximum blood alcohol levels of 80mg per dl.

Separately, drinking excessive alcohol can temporarily reduce a man's ability to get an erection. That is alcohol working against you rather than against the medicine, and it applies whichever PDE5 inhibitor you take.

Alcohol use with tadalafil should still be discussed with a prescriber, particularly in people taking other medicines that lower blood pressure.

Back Pain

Back pain is a recognised common adverse effect of tadalafil. Sildenafil's commonly reported effects are different, and include headache, flushing, indigestion, nasal congestion and visual disturbances.

For tadalafil, no adverse reaction frequency table was verifiable from UK regulator sources within the material reviewed for this page. So this page does not publish one, and specifically does not publish a back pain frequency.

That will be unsatisfying if you came here for a number, and it is the correct outcome. Publishing an unverified frequency, or implying that sildenafil's figures apply to tadalafil, would be worse than saying nothing. The patient information leaflet inside your pack lists the adverse reactions for the product you have actually been supplied, and that is the document to read.

If you are experiencing back pain on either medicine, that is a conversation with a prescriber rather than something to diagnose from a comparison page.

Shared Emergency Signs

For both medicines, the same emergency signs apply. Chest pain, fainting, an erection lasting longer than 4 hours, a sudden decrease or loss of vision or hearing, and an allergic reaction all need immediate medical attention.

Nitrates and nitric oxide donors are contraindicated with both. Because tadalafil has a longer duration of action, the interaction can persist longer. In an emergency requiring nitrates, the tadalafil product information specifies a minimum 48-hour interval and close medical supervision.

Price

Standard prices at EveryDayMeds, before any code or offer, start as follows.

Three points make those figures more useful than they first look.

Compare per tablet, not per pack. Pack sizes differ between products and between strengths, and a headline pack price tells you very little on its own. Divide by the number of tablets before drawing any conclusion.

Compare like formats. Setting an on demand price against a daily price is not a comparison. A daily product supplies continuous treatment and an on demand product supplies a number of occasions, so the meaningful figure is what a typical month or year costs given how often you actually need treatment.

Watch for discounted figures. A price shown after a code has been applied is not the standard price, and comparing somebody's discounted figure against another standard price is two different measurements rather than a comparison. Every figure above is a standard price.

Prices are standard prices at the time of writing and may change. Cost is a reasonable way to choose between pack sizes once a prescriber has established what you are being supplied. It is not a basis for choosing which medicine you take.

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Switching Between Them

From Sildenafil to Tadalafil

Switching is a clinical decision, and the reason for switching matters more than the mechanics.

Common reasons people raise it include wanting a longer window, finding the timing of an on demand tablet inconvenient, or not getting on with one medicine. All are legitimate things to bring to a consultation.

Do not take sildenafil and tadalafil together unless specifically instructed by a prescriber. When switching, the timing should be determined by the prescriber, taking into account the previous dose, tadalafil's longer duration of action and your other medicines.

From Tadalafil to Sildenafil

The same principles apply in reverse, with one addition specific to this direction.

Because tadalafil can remain effective for up to 36 hours, a prescriber should determine when it is appropriate to start sildenafil rather than assuming the medicines can be switched immediately.

Anyone moving from tadalafil to sildenafil should be aware that the previous medicine may still be present for longer than they expect, which is a reason not to rush the transition. A consultation is where a switch gets assessed, including a fresh look at your current medicines and any change in your health since the last supply.

Can You Take Both Together?

No. This is a plain no rather than a caution.

They are the same class working through the same pathway. Taking both means the blood-pressure-lowering effects add together, and the result is a larger fall than either produces alone. Neither product's licence contemplates combining them, and no benefit from doing so is documented.

The situations where people consider it are all better addressed another way. If one is not working well, the answer is a prescriber review rather than adding a second. If the timing is inconvenient, that is a conversation about which format suits you. If a tablet seems weak, the documented explanations include food, alcohol, other medicines and too few attempts, none of which is fixed by stacking.

Do not exceed the prescribed dose or dosing frequency.

Sildenafil vs Tadalafil for Older Men

Age changes how the body handles sildenafil, and there is a documented figure for it. Healthy volunteers aged 65 or over had reduced clearance of sildenafil, resulting in approximately 90% higher plasma concentrations of sildenafil and its active metabolite. The reviewed material also notes that dose adjustments are not required on the basis of age alone.

No equivalent verified figure for tadalafil was available for this page, so none is quoted.

What applies to both is that age tends to bring more of the things that actually determine suitability. More prescribed medicines, a higher likelihood of cardiovascular conditions, and changes in kidney and liver function all matter more than age itself. That is why a full and current medicines list is the most useful thing an older man can bring to a consultation.

Erectile dysfunction should be medically assessed, particularly when it is new, persistent or accompanied by cardiovascular risk factors or other health concerns.

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