Sildenafil vs. Tadalafil: Which Ingredient Works Best?

Ever wondered which works best, Viagra or Cialis?

Principally used to treat erectile dysfunction (ED), sildenafil and tadalafil are the active ingredients found in Viagra and Cialis respectively. They both come from the same family of drugs and work in similar ways to improve blood flow to the penis. Both have high success rates for treating ED as well as offering some other benefits but each has their own unique profile; from the time it takes to work to the duration of their performance enhancing influence as well as any side effects.

In this feature, we take a look at exactly what these two ‘wonder’ drugs promise, what they deliver and which one has the best key ingredients so you can choose which is right for you.

Sildenafil & Tadalafil: What Are They?

Both sildenafil and tadalafil are types of drugs called PDE5 inhibitors. Developed to treat erectile dysfunction, they both work by blocking an enzyme called phosphodiesterase type 5.

Sildenafil vs Tadalafil - erectile dysfunction
More than 30 million men in the United States are thought to suffer from ED. Sildenafil and tadalafil are two ways to help treat this condition. Image via Wikipedia Commons.

In those men who don’t suffer from ED, sexual arousal starts a process which leads to the production and release of nitric oxide. In turn, this activates an enzyme called guanylate cyclase which helps to produce cyclic guanosine monophosphate (cGMP).

cGMP is an essential component for healthy erections and regulates blood flow to (and from) the penis but PDE5 prevents cGMP from functioning.

Taking PDE5 inhibitors therefore allows cGMP to do its job and to do it for longer and more efficiently.

The result is a more engorged penis that can stay hard for hours.

Both drugs are also used to treat pulmonary arterial hypertension as well as some other cardiovascular conditions including Reynaud’s Syndrome.

So, if they both work in the same way, what are the main differences between them?


Discovered by Pfizer in 1993 whilst looking for a treatment for heart-related chest pain, sildenafil is probably the most common type of PDE5 inhibitor.

Sildenafil vs Tadalafil - what is viagra
Image via Wikipedia Commons.

The project to find a way to treat cardiovascular problems was almost abandoned until one observant nurse at Pfizer noticed that all of the men who were enrolled in the study happened to be lying on their stomachs. Doing so to conceal their spontaneous erections caused by the medication, the unexpected side effects of sildenafil were to revolutionize the sexual health industry.

Marketed under the brand name, Viagra, this little blue ‘miracle’ pill is one of the world’s most counterfeited drugs and has made the pharma company billions of dollars in profit.

Now available in generic form after the licensing period expired in 2017, sildenafil is the active ingredient in many Viagra-type products.


Sildenafil is available in various strengths (typically, 25mg, 50mg and 100mg) with the common dosage being 50mg.

Sildenafil should only be used once in a 24-hour period.

Side Effects

The most common side effects caused by sildenafil are headaches, nasal congestion and facial flushing. However, some men also report the following complaints when taking Viagra (or similar):

  • Dizziness
  • Upset stomach
  • Nausea
  • Rash
  • Muscle aches
  • Vision changes

Most symptoms are mild but if you experience any of these side effects and they do not go away then you are advised to speak to a physician.

Rarely, the drug can cause prolonged erections and severe low blood pressure and sudden hearing loss. There has also been some evidence in clinical trials of a very low risk of sildenafil causing heart attack, stroke or ventricular arrhythmias. It is therefore not recommended that you medicate using this drug if you have any recent health history of cardiac-disease, low blood pressure, eye, kidney or liver disease.

Time to Work and Duration of Action

Sildenafil can be taken four hours to thirty minutes before sexual activity but for the best results, it is recommended that you take the required dose 60 minutes beforehand.

If you take the tablet with a high-fat meal, it can take longer to work.

The effects of the drug last for up to four hours.


In its generic form, the wholesale price of sildenafil in the United States is around $1.00.


Approved for use in 2003, tadalafil is more commonly known as Cialis but is now also available in generic form after exclusive licensing expired.

Sildenafil vs Tadalafil - what is cialis
Image via Wikipedia Commons.

Like Sildenafil, Tadalafil is available to take in a single dose as required but is also available as a daily medication. This means you don’t have to remember to take it prior to intercourse as its effects are cumulative in the body so you can be more spontaneous. And, no, this doesn’t mean you will have a raging boner for the rest of your life if you are taking it daily. The small and regular doses means that it’s active when you become sexually aroused. In this way, Tadalafil is often prescribed as an ongoing treatment for ED.


Tadalafil is available in doses of 2.5mg, 5mg, 10mg and 20mg with the most common dosage being:

  • 10-20mg when taken as required
  • 5-5mg when taken daily

Side Effects

Side effects with tadalafil are virtually identical to those experienced when using sildenafil, namely:

  • Nasal congestion
  • Headaches
  • Facial flushing
  • Muscle pain
  • Nausea

This drug can also cause prolonged erections, vision problems and hearing loss as well as low blood pressure.

Always check the drug interactions information before using tadalafil as it is not recommended to take this medication with some other prescription and even non-prescription pharmaceuticals.

Time to Work and Duration of Action

Tadalafil takes at least 20 to 30 minutes to become effective and should be taken no sooner that 30-60 minutes before sexual activity.

Unlike sildenafil, tadalafil stays in the body for up to 36 hours. This doesn’t mean that you will have a solid erection for a day and a half but you should notice the effects of the drug working if you are sexually aroused during this period.

As with sildenafil, any high fat foods taken with the drug can reduce the absorption rate and therefore increase its time to full efficacy. According to some sources, this is to a lesser extent that sildenafil.


In its generic form, the wholesale price of tadalafil in the United States is $1.91.

Sildenafil vs Tadalafil: Which One is Best?

Both tadalafil and sildenafil have similar active ingredients (PDE5 inhibitors) which can help improve erectile function in patients suffering from some forms of ED. They can also help increase the blood flow to the penis of men who do not suffer from ED but who want to experience harder and longer erections.

viagra vs cialis- which is best
The little blue pill, Viagra, may be the best known but is it the best option. Image via Pixabay.

The effects of tadalafil last longer than sildenafil plus the fact you can take this drug daily means that you can be more spontaneous on tadalafil. This is ideal for men who expect to have more than two sexual encounters per week.

Tadalafil also works faster to produce results needing only 20-30 minutes whilst sildenafil takes 30-60 minutes. The former also seems to be less affected by what kind of food you have when you take the tablet.

Both drugs have similar profiles when it comes to the kinds of side effects which may be experienced but these will vary by patient. If you get some side effects with one then you may want to try the other to see if this improves the complaints. Alternatively, varying the dosage may also decrease the kinds, and levels, of side effects you experience.

On paper, tadalafil appears to offer more benefits by acting faster and longer than sildenafil. Studies in both China and Italy concluded that more men who conducted their trials preferred the results with tadalafil.

The difference between the two is very little and the preference seems mainly to be for duration and time to work rather than any success rate. Certainly, there is no evidence to suggest that either works better than the other in terms of how hard your penis gets and whether they can improve your stamina.

The main difference with the two drugs is the price with generic versions of tadalafil costing almost double that of sildenafil. Of course, where and how much you buy will affect the price and you could find some cheaper options available online. However, always exercise caution when buying over the internet as the origin cannot always be verified. It’s recommended that you source either drug from a reputable retailer such as a registered pharmacist.

Sildenafil vs Tadalafil -best drug for ed
ED is no laughing matter but drugs like tadalafil and sildenafil can help….as can other options. Image via PxHere.

In conclusion, tadalafil would seem the better option although your mileage may vary so be prepared to try both (at different times!) and to vary the dosage to suit you. Every drug affects people in different ways and sometimes it can take a few trials to get the body used to the effects.

And remember, always seek medical advice if you experience any prolonged or serious side effects and do not take either of these drugs if you are using medications relating to those conditions detailed above.

Good luck in your pursuit for stronger, longer and more pleasurable erections! Just remember that if you are looking for performance pills then there are other alternatives available. Check out our recent feature on the Best Sex Performance Pills.

Featured image via Flickr.

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