Sildenafil vs Tadalafil

Erectile dysfunction is a common sexual health issue, affecting millions of men worldwide. Contemporary medicine offers several effective solutions. Oral phosphodiesterase type 5 (PDE-5) inhibitors are the predominantly used first-line treatment, while Sildenafil and Tadalafil hold the highest ranks among other ED medications for men.

Sildenafil and tadalafil as active ingredients for ED

Sildenafil and Tadalafil, marketed under various brands, are the most commonly prescribed PDE-5 inhibitors, ranking in the Top-10 ED pills worldwide. Both medications are designed to treat erectile dysfunction, and both belong to the same class of drugs. However, they differ in pharmacokinetic properties, duration of action, and dosing regimens, which may influence treatment selection.

Knowing the difference between tadalafil and sildenafil helps patients and clinicians choose the most appropriate erectile dysfunction treatment. This is based, of course, on:

• Medical history
• Expectations
• Personal preference
• Frequency of sexual activity and desired duration of the effect

What are sildenafil and tadalafil?

Sildenafil, often better known under its brand name Viagra, was the first oral PDE-5 inhibitor approved for use in the treatment of erectile dysfunction. Still today, it is one of the most commonly prescribed erectile dysfunction medications globally [1]. The drug works by enhancing natural erectile responses during sexual stimulation. It is usually taken as needed before sexual activity.

Sildenafil is available in several strengths, including 25 mg, 50 mg, and 100 mg, setting a kind of standard for ED treatment [2]. That is why, for users aware of sildenafil’s potential, it is not unusual to compare it to other ED medications. Not surprisingly, online search examples such as “sildenafil 100mg vs tadalafil 10mg” or “sildenafil vs tadalafil” are common when deciding the most suitable option.

Sildenafil is also available as a generic version. This makes it the most affordable option for many patients.

Tadalafil, also better known under its marketed brand name Cialis, is another PDE-5 inhibitor used to treat erectile dysfunction. The drug has a longer recorded duration of action of up to 36 hours, so some users also call it “the weekend pill”. It is used when needed or as a low-dose daily therapy. For most users, tadalafil is an alternative to Viagra, often preferred by individuals who desire more spontaneity and a longer-lasting effect [3].  Generic Cialis is also available, reducing the cost of ED treatment.

How do sildenafil and tadalafil work inside the body?

There is not much to compare when it comes to sildenafil vs tadalafil mechanism of action. Fundamentally, both medications work the same. They inhibit the PDE-5 enzyme, which regulates blood flow in the penis. Consequently, nitric oxide is released during sexual stimulation, which triggers a cascade that increases cyclic GMP levels. This leads to relaxation of smooth muscle in the blood vessels, increasing blood flow in general (and improved flow to the penis) [4].

In short, sildenafil and tadalafil help maintain higher levels of cyclic GMP, thus supporting stronger and more sustained erections, but not without sexual stimulation. Therefore, men must be sexually aroused for the medication to help them achieve erections [5].

So, why are there differences between the two after all? Well, although both medications contain active ingredients of the same drug class, subtle pharmacokinetic differences cause the well-recorded variations in onset and duration of action.

How quickly do sildenafil and tadalafil start to work?

Sildenafil and tadalafil take approximately equally long to start working.

Sildenafil Onset

Most users notice the effects within half an hour to one hour when taking sildenafil [6]. It is generally recommended to take the medication on an empty stomach. That’s because fatty foods can delay absorption and reduce effectiveness. This is a key point when comparing sildenafil vs other ED pills.

The predictable onset of sildenafil makes it a common starting dose option for many first-time users of any kind of erectile dysfunction treatment.

Tadalafil Onset

When taking tadalafil, users can expect the first effect within twenty minutes to one hour. [7] So, sometimes a bit sooner than with sildenafil. In addition, this ED medication is less affected by food intake. Therefore, tadalafil’s pharmacological profile allows more flexibility around the planned time of sexual activity and meals.

How long do effects last?

Another important factor is the duration of action. Let us take a more detailed look:

Sildenafil Duration

The typical effectiveness window for sildenafil is four to six hours [8]. This is the time users have to respond to sexual stimulation after a single dose of the medication, not the duration of a continuous erection.  Research suggests that this is enough time for most men to support sexual activity. The downside is a shorter half-life, meaning less spontaneity compared to tadalafil.

Tadalafil Duration

Tadalafil is well-known for its long lasting effects (up to thirty-six hours) [9].  In discussions about other ED drugs vs tadalafil, duration is often the most significant differentiator. Longer duration of action also allows a more natural timing and less performance pressure.

Dosing Differences and Flexibility

Dosing is one of the main differences between these two medications:

Sildenafil Dosing

Sildenafil is typically prescribed in 25 mg, 50 mg, or 100 mg doses. The 50 mg tablet is the gold standard of first-time ED therapy and often the starting dose. It can be adjusted depending on response and side effects. Some men may require higher doses, such as 100 mg, for optimal results [10]. The main difference in tadalafil vs sildenafil dosage is that sildenafil is taken only as needed, not daily.

Tadalafil Dosing

With on-demand dosing, tadalafil users typically require 10 mg or 20 mg before anticipated sexual activity [11]. This is a noticeably lower quantity of active ingredient, mostly due to differing half-lives between the two drugs.  

Tadalafil Daily Dosing

With tadalafil for erectile dysfunction, there is a possibility to take a daily low dose of the medication of 2.5 or 5 mg. Daily therapy is particularly useful for sexually active users. It allows them to engage in sexual activity at any time without planning (e.g., multiple times a week) [12].

Tadalafil vs sildenafil side effects

For most users, both sildenafil and tadalafil are generally safe. However, with both medications, there are some commonly recorded side effects. There are also some differences here:

Common Side Effects

Common side effects of both medications relate to systemic vasodilation and mild changes in blood pressure [13]. They include:

• Headache
• Flushing
• Nasal congestion
• Indigestion
• Mild dizziness

Are there any notable differences between active ingredients?

The short answer is yes! For example, sildenafil is more commonly associated with visual disturbances, such as a blue tinge to vision. Tadalafil may cause back pain or muscle aches in some men.

Overall, in comparing tadalafil vs sildenafil safety, both are generally safe for most healthy men, but require evaluation of medical history.

Warnings and Contraindications

Certain groups of users are at a greater risk of experiencing unwanted effects of ED medications [14]. These include men with:

• Established cardiovascular / heart disease, including coronary artery disease or heart failure
• A recent myocardial infarction (heart attack) or a recent stroke
• Unstable angina (chest pain that is not well controlled or occurs at rest)
• Severe hypotension or uncontrolled hypertension

In terms of drug interactions, both medications can interact with nitrates and certain other medication, leading to dangerous drops in blood pressure. They may also interact with medications used to treat fungal infections and bacterial infections, as well as other drugs metabolised by CYP3A4. All of this makes the awareness of potential drug interactions essential.

Which one is more effective?

When comparing sildenafil vs tadalafil effectiveness, we can confidently state that clinical trials show both drugs are highly effective. This means that most men achieve a satisfactory erection with appropriate dosing in both cases. Research suggests that daily tadalafil may offer greater benefits than on-demand tadalafil or sildenafil for men with erectile dysfunction, particularly in those experiencing symptoms of low mood or anxiety. [15].

Viagra success rates vary by underlying cause. In clinical trials, sildenafil produced successful intercourse attempts in 57% of cases on average, with 83% of men achieving at least one successful sexual encounter during the treatment period. Additionally, 78% of men taking sildenafil reported a noticeable improvement in the quality of their erections overall. [17]

Tadalafil (Cialis) demonstrates comparable overall efficacy to sildenafil, with clinical trials showing improvement in erectile function in approximately 75-85% of men. [18]

Neither medication directly increases sexual desire or libido. So, only the physiological ability to respond to arousal is affected. However, the positive psychological effect of successful erections cannot be underestimated.

Which ones do users prefer?

Studies suggest patient choice often comes down to lifestyle and personal preference. Men who prefer to take the medication only when needed may choose sildenafil. On the other hand, those with a more active or unpredictable sexual life may prefer tadalafil [16].

This goes to show that questions such as: Which is better, sildenafil or tadalafil? Or what is the best ED treatment? Do not have universal answers. The right choice depends on three factors:

• Frequency of sexual activity
• Tolerance of side effects
• Individual response
• Convenience and preference for daily versus on-demand dosing

What is the cost and access to sildenafil and tadalafil in the UK?

When buying sildenafil or looking to order tadalafil in the UK, there are some factors to consider:

First, in the UK, both medications are mostly available only by prescription. As an exception, sildenafil is available over the counter in lower strengths (Viagra Connect).

Second, when comparing tadalafil vs sildenafil price and tadalafil vs sildenafil cost, users should know that generic options significantly reduce expenses. Practically, that means that the generic version of sildenafil is typically less expensive than branded Viagra, while generic Cialis is more affordable than branded Cialis.

Here is an average price comparison:

FAQs

As they are the most widely prescribed and used, both medications are the subject of many disputes and discussions.

Is tadalafil more effective than sildenafil?

In terms of erection quality, studies show similar success rates. Therefore, there is no point in debating: “Is tadalafil better than Viagra?” or “Is tadalafil stronger than Viagra?” The choice between the two largely comes down to personal preference, lifestyle, and how each individual responds to treatment.

Can I use tadalafil and sildenafil together?

No. Taking both sildenafil and tadalafil together increases the risk of side effects and dangerous drops in blood pressure.

What is better: tadalafil or tadalafil daily?

Daily tadalafil is ideal for men with frequent sexual activity. On-demand dosing may suit others better. It depends on lifestyle and expectations.

Which is better for spontaneous sex, sildenafil or tadalafil?

Tadalafil’s extended window makes it more suitable for spontaneity. Its long-lasting effects reduce the need for precise timing.

Which option is more suitable for first-time users: sildenafil or tadalafil?

Sildenafil is the more common first-line ED treatment, especially at a lower starting dose. Some doctors may suggest tadalafil, based on lifestyle and other factors.

The Bottom Line

When comparing sildenafil or tadalafil, there is no clear winner. Both are effective treatments that improve blood flow and help men achieve erections during sexual stimulation. The key differences lie in:

• Onset
• Duration
• Dosing flexibility
• Side effect profile
• Price

The optimal choice should be based on individual medical history, treatment response, and discussion with a qualified healthcare provider.

References:

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[2] Smith, B. P., & Babos, M. (2023). Sildenafil. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK558978/

[3] European Association of Urology. (2024). EAU guidelines on sexual and reproductive health: Management of erectile dysfunction. European Association of Urology. https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/management-of-erectile-dysfunction

[4] Andersson K. E. (2018). PDE5 inhibitors - pharmacology and clinical applications 20 years after sildenafil discovery. British journal of pharmacology, 175(13), 2554–2565. https://doi.org/10.1111/bph.14205

[5] Fahmy, G., & Hess, J. (2024). Tadalafil. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK603743/

[6] Goldstein, I., Burnett, A. L., Rosen, R. C., Park, P. W., & Stecher, V. J. (2019). The Serendipitous Story of Sildenafil: An Unexpected Oral Therapy for Erectile Dysfunction. Sexual medicine reviews, 7(1), 115–128. https://doi.org/10.1016/j.sxmr.2018.06.005

[7] Zhou, Z., Chen, H., Wu, J., Wang, J., Zhang, X., Ma, J., & Cui, Y. (2019). Meta-Analysis of the Long-Term Efficacy and Tolerance of Tadalafil Daily Compared With Tadalafil On-Demand in Treating Men With Erectile Dysfunction. Sexual medicine, 7(3), 282–291. https://doi.org/10.1016/j.esxm.2019.06.006

[8] Nik-Ahd, F., & Shindel, A. W. (2022). Pharmacotherapy for Erectile Dysfunction in 2021 and Beyond. The Urologic clinics of North America, 49(2), 209–217. https://doi.org/10.1016/j.ucl.2021.12.002

[9] Prasetyo, D. T., Raharja, P. A. R., Mantiri, B. J., Ringoringo, D. R. L., Rahman, I. A., Felizio, J., Tambunan, M. P., Fadhly, S. F., & Rahardjo, H. E. (2019). Tadalafil Once a Day for Men with Erectile Dysfunction: Is It Superior than On-Demand Administration?. Acta medica Indonesiana, 51(3), 275–281.

[10] Jannini, E. A., & Droupy, S. (2019). Needs and Expectations of Patients with Erectile Dysfunction: An Update on Pharmacological Innovations in Phosphodiesterase Type 5 Inhibition with Focus on Sildenafil. Sexual medicine, 7(1), 1–10. https://doi.org/10.1016/j.esxm.2018.10.005

[11] Bolat, M. S., Cinar, O., Akdeniz, E., & Aşcı, R. (2018). Low dose daily versus on-demand high dose tadalafil in diabetic patients with erectile and ejaculatory dysfunction. International journal of impotence research, 30(3), 102–107. https://doi.org/10.1038/s41443-018-0019-5

[12] Wang, Y., Bao, Y., Liu, J., Duan, L., & Cui, Y. (2018). Tadalafil 5 mg Once Daily Improves Lower Urinary Tract Symptoms and Erectile Dysfunction: A Systematic Review and Meta-analysis. Lower urinary tract symptoms, 10(1), 84–92. https://doi.org/10.1111/luts.12144

[13] Lui, J. L., Shaw, N. M., Abbasi, B., Hakam, N., & Breyer, B. N. (2023). Adverse reactions of PDE5 inhibitors: An analysis of the World Health Organization pharmacovigilance database. Andrology, 11(7), 1408–1417. https://doi.org/10.1111/andr.13430

[14] Klein, M. R., & Shindel, A. W. (2023). Prescribing PDE5 inhibitors: best practices, common practices, and controversies. Current Sexual Health Reports, 15(3), 244-251. https://link.springer.com/article/10.1007/s11930-023-00367-w

[15] Gagal, S., Sidana, A. K., Agrawal, A., & Singh, S. (2025). Comparative efficacy of on-demand Sildenafil, Tadalafil and daily Tadalafil for treatment of erectile dysfunction: A 12-week randomized controlled study. Indian journal of psychiatry, 67(12), 1136–1144. https://doi.org/10.4103/indianjpsychiatry_998_24

[16] von Büren, F. R., Maître, S., & Salem, S. (2022). Patient preferences and treatment patterns in phosphodiesterase‑5 inhibitor therapy for erectile dysfunction: A real‑world comparison of tadalafil and sildenafil. European Urology Focus, 8(5), 1408–1415. https://doi.org/10.1016/j.euf.2021.04.019

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