Sildenafil vs Tadalafil vs Vardenafil: How the Three ED Medications Actually Differ

Erectile dysfunction is far more common than most men assume. The National Institutes of Health estimates that between 30 and 50 million men in the United States have it.⁷ In the landmark Massachusetts Male Aging Study, 52% of men aged 40 to 70 had some degree of it.⁸

Mayo Clinic describes male arousal as a process involving the brain, hormones, emotions, nerves, muscles and blood vessels, and notes that ED can come from a problem with any of them, often a mix of physical and mental factors.⁹ The most common physical causes are conditions that affect blood flow, including heart disease, high blood pressure and diabetes.^10,11

How the three medications work

An erection depends on nitric oxide relaxing the smooth muscle in the penis so blood can flow in. That signal runs through a molecule called cGMP, which the enzyme PDE5 breaks down. Sildenafil, tadalafil and vardenafil all block PDE5, so the signal lasts longer when you are aroused.¹ Without sexual stimulation, nothing happens. These medications do not cure ED or increase desire.⁴

Side by side, from the FDA labels

Sildenafil

The first of the class and still the most familiar. Its label calls for a dose about an hour before sex, within a window of 30 minutes to four hours. The catch is food: a high-fat meal pushes the peak back by about an hour and cuts it by roughly 29%.¹

Tadalafil

The long-acting option. Its label reports improved erectile function for up to 36 hours after a dose, with no food restriction, and it is the only one of the three approved as a low daily dose, which removes the need to time anything.³

Vardenafil

Similar in timing to sildenafil, and also affected by heavy meals, though the label reports a wider range of effect.¹² It is also sold as an orally disintegrating tablet that dissolves on the tongue; that version is absorbed more completely than the standard tablet and the two are not interchangeable.^13,14 In a randomized trial, the dissolving form beat placebo on every efficacy measure.¹⁵

Dissolving and sublingual forms

Forms that dissolve in the mouth are increasingly common. The evidence is real but modest. A small study of a sildenafil film placed under the tongue found higher blood levels at 15 minutes than with the tablet.¹⁶ A randomized trial of a sildenafil dissolving strip found effectiveness comparable to the tablet, with onset about seven minutes earlier.¹⁷ Treat claims of dramatically faster results with caution.

Apomorphine: a different mechanism

Apomorphine works in the brain rather than on blood vessels: it stimulates dopamine receptors involved in arousal. A sublingual form was approved in the European Union for ED in 2001 under the name Uprima, and the authorization lapsed in 2006 when the company did not renew it for commercial reasons.¹⁸ In trials, a 3 mg dose outperformed placebo, with a median time to erection of about 19 minutes; nausea affected 7% of men at that dose.¹⁹ A 2020 meta-analysis found it improved successful intercourse attempts by 6–27% over placebo.²⁰ On its own it is less effective than PDE5 inhibitors.²¹

What about combining them?

Because the medications act on different timescales and, in apomorphine's case, through a different pathway, combining them is an active area of interest. In one trial of 180 men, daily tadalafil plus as-needed sildenafil improved erectile function more than tadalafil alone, particularly in severe ED, without more side effects.²² A 2021 review found combinations gave a modest overall benefit, while noting that the studies varied widely.²³ The Cialis label, for its part, says combinations with other PDE5 inhibitors have not been studied.³ That is why combination products are compounded prescriptions, made for an individual patient after a clinician decides they are appropriate. Compounded drugs are not FDA-approved.²⁴

Several online providers now offer compounded combinations. Quattro by Vea Health is the only one we found that combines all three PDE5 inhibitors, sildenafil, tadalafil and vardenafil, with apomorphine in a single sublingual dose.^25,26,27,28

Lifestyle still matters

The AUA guideline notes that diet changes and more physical activity may improve erectile function.⁵ In a randomized trial of obese men, a lifestyle program raised erectile function scores significantly, and 17 men in the intervention group reached normal function versus 3 in the control group.²⁹ Stress and performance anxiety also play a real role: performance anxiety affects an estimated 9–25% of men.³⁰

When to see a clinician

Mayo Clinic recommends seeing a healthcare professional if you are worried about your erections, have diabetes or heart disease, or have other symptoms alongside ED.⁹ The AUA guideline calls for a full medical, sexual and psychosocial history and treats ED as a risk marker for cardiovascular disease.^5,31

Frequently asked questions

Which ED medication works fastest?

On their FDA labels, sildenafil and vardenafil both reach peak blood levels in about an hour when taken on an empty stomach, and tadalafil in about two hours. Dissolving and sublingual forms may be absorbed somewhat faster, but the evidence for faster onset comes from small studies.

Which ED medication lasts longest?

Tadalafil. Its label says it improves erectile function for up to 36 hours after a dose, compared with roughly four to five hours for sildenafil and vardenafil.

Can I take ED medication after a meal?

Tadalafil can be taken without regard to food. A high-fat meal delays sildenafil by about an hour and lowers its peak level, and reduces the peak level of vardenafil.

Is it safe to combine ED medications?

Some studies show a modest benefit from combining a daily low dose of tadalafil with as-needed sildenafil, but the Cialis label says combinations with other PDE5 inhibitors have not been studied. Combining should only happen under a clinician's direction.