Many men face a common problem that affects both confidence and intimacy. Erectile dysfunction (ED) can cause stress and hurt personal relationships.
Sildenafil and tadalafil work in unique ways to improve blood flow and support a lasting erection. Their different features can be important when choosing the right treatment for you.
In this article, you will learn how these treatments work, discover their benefits, and understand what to expect.
| 🔑 Key Takeaways ➤ Both drugs block the PDE5 enzyme to help increase blood flow to the penis. ➤ Sildenafil works faster and reaches its peak effect in about one hour. ➤ Tadalafil has a longer effect and may work for up to 17.5 hours. ➤ Sildenafil may affect vision, while tadalafil may cause back pain or muscle aches. |
Mechanism of Action
Both sildenafil and tadalafil work similarly, but have slight variances, leading to their differences in onset and duration of effect. They also have slightly different side effect profiles.
Sildenafil
Sildenafil works by blocking the enzyme called PDE5 in the smooth muscle of your penis. When you are sexually stimulated, nitric oxide is released. This boosts the production of cGMP.
Higher levels of cGMP cause the smooth muscle to relax and the blood vessels to widen, which increases blood flow.
In simple terms, sildenafil stops the breakdown of cGMP so that your erection can last longer. It also affects another enzyme, PDE6, which can lead to mild changes in vision.
Tadalafil
Tadalafil also blocks PDE5 to boost the levels of cGMP in your penis. This action helps relax the smooth muscle and widen the blood vessels, increasing blood flow during arousal. However, tadalafil is slightly different because it can also affect PDE11.
This difference in selectivity may lead to side effects like back pain or muscle aches. While both drugs work by protecting cGMP from being broken down, they differ in the additional enzymes they may influence, which explains their unique side effect profiles.
Efficacy and Duration
Both sildenafil and tadalafil are effective treatments for erectile dysfunction, but they differ in how long they last and their probability of success.
Sildenafil
Sildenafil has been studied in a vast number of clinical trials. In one network meta‐analysis encompassing 184 articles and 179 trials, a 25 mg dose of sildenafil was found to be statistically superior in improving erectile function, with a 98% probability of being the most effective treatment. This strong performance makes it a highly regarded option among PDE5 inhibitors.
At a 50 mg dose, sildenafil still shows robust efficacy—with an 80% probability of being highly effective. Across various studies, its overall efficacy in improving erectile function has been reported between 57% and 83%.
Thus, Sildenafil offers a reliable improvement for many men, whether their erectile dysfunction has an organic or psychogenic origin.
Tadalafil
Tadalafil, by contrast, offers a different balance between efficacy and duration. Clinical studies indicate that tadalafil, at doses of 10 mg and 20 mg, has shown efficacy probabilities of 73% and 76% respectively. These figures demonstrate that tadalafil is a very effective option, comparable to sildenafil in terms of improving erectile function.
The effectiveness of tadalafil has also been confirmed in patients with additional complications, such as diabetes mellitus, where it has shown promising results. Its reliable improvement in scores on the International Index of Erectile Function reinforces its status as a first-line treatment option for erectile dysfunction.
Onset Time and Absorption Duration
While sildenafil acts faster, tadalafil offers a longer window of effectiveness, making it a more flexible option for some users.
| Sildenafil | Tadalafil | |
| Onset | Rapid – reaches peak levels within 30–120 minutes (typically ~60 minutes in a fasted state) | Slower – may take up to 2 hours to reach maximum concentration |
| Duration | Designed for shorter-term use, aligning with planned activity | Extended – effects can last for around 17.5 hours |
Sildenafil
Sildenafil is known for its rapid absorption when taken orally. In the fasted state, the maximum observed plasma concentrations are reached within 30 to 120 minutes, with a median time of about 60 minutes. This quick onset makes sildenafil a popular choice for those who plan their sexual activity ahead of time.
However, if you take sildenafil with a high-fat meal, the onset is delayed by about 60 minutes and the peak concentration is reduced by approximately 29%.
Sildenafil has an absolute bioavailability of around 40%, which means that a significant portion of the active drug reaches your bloodstream after oral administration. Once absorbed, it distributes well into tissues, as indicated by a steady state volume of distribution of roughly 105 liters.
Additionally, both sildenafil and its active metabolite bind to plasma proteins at about 96%, ensuring a consistent delivery to target tissues.
Tadalafil
Tadalafil presents a contrasting profile when it comes to onset time. While some studies note that you may experience effects as early as 30 minutes after taking a dose on an as-needed basis, more detailed pharmacokinetic data from clinical settings indicate that tadalafil has a slower onset overall.
In fact, tadalafil may require up to 2 hours to reach its maximum plasma concentration. This slower peak can be advantageous for those who prefer a longer window of readiness, even if it means waiting a bit longer for the full effect.
Tadalafil is absorbed orally in tablet form and is available both for daily dosing and as-needed use. Although its bioavailability is less frequently highlighted than for sildenafil, the key takeaway is that tadalafil’s absorption is more gradual.
This slower absorption contributes to its extended half-life of around 17.5 hours, ensuring that its effects are sustained over a much longer period. The gradual uptake allows for a flexible treatment approach, especially for individuals seeking spontaneous intimacy without the need to time their dosing as strictly.
Side Effects
Both sildenafil and tadalafil share common side effects, but tadalafil’s longer duration and unique interaction with PDE11 can lead to some distinct differences in side effect profiles.
Sildenafil
When taking sildenafil, common side effects include:
- Headache
- Flushing of the face
- Dyspepsia (upset stomach or diarrhea)
- Nasal congestion
- Abnormal vision (e.g., a transient blue tinge or blurred vision)
- Dizziness
- Rash
These side effects are generally mild to moderate and tend to resolve on their own after a few hours.
Tadalafil
Tadalafil shares many side effects with other PDE5 inhibitors; however, there are some differences due to its unique pharmacologic profile. Common side effects include:
- Headache
- Flushing
- Dyspepsia
- Nasal congestion
- Dizziness
Additionally, because tadalafil has some cross-reactivity with PDE11, users may also experience:
- Back pain
- Myalgias (muscle aches)
- Limb pain
These side effects are usually mild or moderate and tend to be transient.
Safety and Considerations
Both sildenafil and tadalafil require careful use, especially for individuals with heart conditions or those taking other medications.
Sildenafil
Certain health conditions and medications can make the use of Sildenafil risky.
Contraindications and Cardiovascular Concerns
Sildenafil must never be taken with nitrates. This is because combining them can cause a dangerous drop in blood pressure. Patients with heart conditions, such as unstable angina or a history of recent heart attacks, should discuss the risks with their doctor.
Sexual activity itself stresses the heart. Sildenafil’s vasodilatory effects may add to that burden. Doctors carefully screen patients for any cardiovascular risk factors before prescribing it.
Drug Interactions and Metabolism
The CYP3A4 enzyme mainly breaks down Sildenafil. This means that drugs like ketoconazole, itraconazole, and erythromycin can increase sildenafil levels in your body. Such interactions can lead to stronger effects and more side effects.
On the other hand, drugs like rifampin may decrease its effectiveness. For patients with liver or kidney problems, clearance is reduced, and a lower dose (often 25 mg) is usually recommended. It is very important to inform your doctor about all medications you are taking so they can adjust your treatment safely.
Tadalafil
As with Sildenafil, certain health conditions and drug interactions can make it risky for some individuals to take Tadalafil.
Contraindications and Extended Cardiovascular Impact
Tadalafil must not be used with any nitrate medications because it can cause a severe drop in blood pressure. Like sildenafil, patients with significant cardiovascular issues need a thorough evaluation before using tadalafil.
However, tadalafil has a much longer half-life—around 17.5 hours—which means its effects last much longer. This prolonged action may expose patients to risks for a longer duration. Your doctor will review your heart health carefully to ensure that tadalafil is safe for you.
Drug Interactions and Prolonged Effects
The CYP3A4 enzyme also metabolizes Tadalafil. If you are taking medications that inhibit this enzyme, such as ketoconazole or ritonavir, the levels of tadalafil in your body can rise significantly.
The long duration of tadalafil means that any drug interactions may have effects that last longer than with shorter-acting drugs. Patients with liver or kidney impairments, as well as older adults, usually need a lower dose to prevent drug accumulation.
Always share your full medication list with your doctor so they can manage potential interactions.
Cost
Here’s how they differ in terms of cost:
Tadalafil
| Dosage (mg) | Price (for 30 tablets) | Notes |
| 2.5 mg | from $105.45 | Less common dose for ED |
| 5 mg | from $18.82 | Common dose for ED and BPH |
| 10 mg | from $19.33 | Slightly higher dose |
For tadalafil, the pricing can vary significantly based on dosage, pharmacy, and whether you are a cash-paying customer.
For instance, a 5 mg oral tablet of tadalafil is priced at around $19 for a 30-tablet supply. This price is quoted for cash-pay customers and may not apply if you have insurance.
It’s important to note that these prices are based on discount programs available through Drugs.com, which can sometimes save you up to 80% or more off the list price.
In addition, prices may change due to location, pharmacy choice, and manufacturer policies, so it’s a good idea to compare prices and check for current discount cards or coupons before purchasing.
Sildenafil
| Dosage (mg) | Price (for specified supply) | Supply Details |
| 25 mg | from $11.47 | For 30 tablets |
| 50 mg | from $9.38 | For 2 tablets |
| 100 mg | from $9.38 | For 2 tablets |
Sildenafil is also available at competitive prices.
For example, a 100 mg oral sildenafil tablet is quoted at around $9 for a supply of 2 tablets, again for cash-paying customers.
Other dosage forms, such as 25 mg tablets, are priced at about $11.47 for a 30-tablet supply, while 50 mg tablets can cost as little as $9.38 for 2 tablets.
As with tadalafil, these prices are based on the Drugs.com discount card program, which is widely accepted at major US pharmacies. These cost figures can help lower your out-of-pocket expenses.
Wrap Up
Deciding whether sildenafil or tadalafil is better depends on what you need. If you want a fast-acting option for planned activity, sildenafil is the better choice. It works quickly and has a strong track record of effectiveness.
However, if you prefer flexibility and a longer duration, tadalafil is the clear winner. It stays active for up to 17.5 hours, making it ideal for spontaneous intimacy without strict timing.
While both drugs work well, tadalafil’s extended effect gives it an edge for those who want fewer restrictions. That said, side effects and personal tolerance matter. Some may prefer sildenafil’s shorter action to minimize exposure, while others may appreciate tadalafil’s convenience. The best option is the one that fits your lifestyle and needs.
Frequently Asked Questions
Can I take Sildenafil and Tadalafil with food?
Tadalafil is not affected by food, but Sildenafil may not work as well if taken with a heavy or fatty meal.
Which one is better for long-term use?
Both work well, but many patients prefer Tadalafil because it lasts longer and can be taken daily in low doses.
Can I take Sildenafil and Tadalafil if I have heart disease?
If you take nitrates for heart disease, do not use Sildenafil or Tadalafil, as it can cause a dangerous drop in blood pressure.
Will Sildenafil and Tadalafil increase my sexual desire?
No, they only improve blood flow to help with erections. You still need to be sexually stimulated for them to work.
Can Sildenafil and Tadalafil cure erectile dysfunction?
No, they help manage symptoms but do not cure ED. The underlying causes, like poor circulation or nerve damage, still exist.
Can I take both Sildenafil and Tadalafil together?
No, taking both can increase side effects without improving effectiveness. Choose one based on your needs and doctor’s advice.
Sources
- Dhaliwal, A., & Gupta, M. (2023). PDE5 inhibitors. In StatPearls. StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK549843/
- Cleveland Clinic. (2004). New competition for Viagra®. Pharmacotherapy Update, VII(2). Retrieved from https://www.clevelandclinicmeded.com/medicalpubs/pharmacy/marap2004/erectiledys.htm
- Madeira, C. R., Tonin, F. S., Fachi, M. M., Borba, H. H., Ferreira, V. L., Leonart, L. P., Bonetti, A. F., Moritz, R. P., Trindade, A. C. L. B., Gonçalves, A. G., Fernandez-Llimos, F., & Pontarolo, R. (2021). Efficacy and safety of oral phosphodiesterase 5 inhibitors for erectile dysfunction: A network meta-analysis and multicriteria decision analysis. World Journal of Urology, 39(3), 953-962. https://doi.org/10.1007/s00345-020-03233-9
- U.S. Food and Drug Administration. (2007). Viagra (sildenafil citrate) prescribing information. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/020895s027lbl.pdf