Erectile Dysfunction
Updated: Sep 21, 2020
Sildenafil vs Tadalafil
Published: Dec 15, 2019

Medically reviewed by Leann Poston, M.D on 9/18/20

You may have noticed that when it comes to medication to treat erectile dysfunction (ED), your options are pretty limited. That isn’t a bad thing, though. There isn’t a whole lot of variety to choose from for a reason; what we currently have works pretty well and targets the root cause of ED with relative precision. A small family of compounds whose name all end with -fil that act in similar, yet slightly different ways within the body to help men manage ED. None of them are lasting cures, but they are effective and all have a relatively safe side-effect profile compared to other medications. The most common comparison is sildenafil vs tadalafil.

Sildenafil (the generic name for Viagra) and tadalafil (the generic name for Cialis) are two of the most common drugs from the -fil family. They are excellent examples of how compounds can have very similar mechanisms of action (how they work) but have quite different ways of getting to that action within the body. In order to decide which one best fits your lifestyle and needs, it is important to understand their different systemic effects. This article is going to help you do just that by covering how exactly both of these ED treatments work, the potential side effects of each, and where to get them prescribed in a more convenient and likely less awkward way than visiting your doctor. 

How sildenafil and tadalafil work

With comparing sildenafil vs. tadalafil, you need to understand that both are PDE5 inhibitors. This means that they block an enzyme whose job is, for lack of a better term, to kill erections. Although this sounds like an enzyme that we could live without, it isn’t.  If PDE5 weren’t doing its job of shutting down the biological pathways that enable an erection, men would be incredibly uncomfortable whenever they were stressed, excited, or scared. This is because without PDE5, whenever we were in a sympathetic state, also known as fight or flight, an erection would occur and likely not go away until our nervous system was calmed down. Every near accident while in traffic, important game for your favorite sports team, and stressful task at work would be accompanied by a persistent visitor. So, in the absence of sexual arousal, PDE5 comes in and does its job, saving us quite a bit of misery. Except sometimes PDE5 does too good of a job and steps in when we don’t want it to.

Erectile dysfunction is defined as the inability to achieve and maintain an erection long enough for completion of sexual intercourse, which certainly can put a damper on a romantic relationship. This is where medications like tadalafil and sildenafil come in. Only when a man is sexually aroused do they essentially block the action of PDE5 and allow an erection to be achieved and maintained. On the basic level of action, they are more or less the same. How they should be taken, in what dosages, and how long they stay effective in the body are quite different, however. 

sildenafil vs tadalafil

Comparing sildenafil and tadalafil

Dosages of tadalafil are generally much lower than that of sildenafil. It is typically recommended that people taking tadalafil and sildenafil start at doses of 5 milligrams and 25 milligrams respectively. How much you specifically will need to take is going to be incredibly individual.

There are quite a few differences between the two which may help narrow down your decision. First, tadalafil’s absorption and efficacy are not affected whatsoever if it is taken with certain foods, while sildenafil’s is. Consuming a moderate or high-fat meal will slow down the absorption of sildenafil as well as reduce its effectiveness.1

Tadalafil is also able to remain active in the bloodstream for far longer than sildenafil. It can remain effective for up to 36 hours in most people, while sildenafil will only remain active for 4-5 hours maximum. On the other hand, sildenafil is absorbed and becomes active much more quickly than tadalafil, taking an average of only 30 minutes to start working. Tadalafil can take 60-120 minutes to start providing benefits. This is why tadalafil is often taken daily at lower dosage levels. Overall, tadalafil can work for much longer (up to 36 hours) but takes longer to be effective. This is an important consideration when deciding which will fit your lifestyle best. Next, consider the potential side effect profiles of each. 

Side effects of sildenafil vs tadalafil

Because tadalafil and sildenafil are such similar compounds, it should be no surprise that their lists of potential side effects are nearly identical. Both drugs can cause facial flushing, headaches, upset stomach, nausea, and disruption that might be significant enough to rule out one or the other as an option for treating ED. You should cover potential side effects more in-depth when speaking with medical professionals, but the disparity between sildenafil and tadalafil’s side effect profile is negligible.

Neither medication should be taken if you are prescribed nitrates and caution should be used when utilizing either compound while on blood pressure medication. It is also important to note that you should never combine PDE5 inhibitors so combining sildenafil and tadalafil to take advantage of their unique effectiveness timelines is not advised. Again, personal preference seems to be the deciding factor between these two compounds. 

Perhaps either sildenafil or tadalafil is proven to be more effective than the other by providing a higher rate of sufficient erections achieved? Well, in a meta-analysis (a study done by analyzing many other studies) completed in 2017, researchers concluded that the efficacy and safety rates of sildenafil and tadalafil were essentially equal.2 They did note, however, that the subjects of the studies, as well as their sexual partners, tended to prefer tadalafil. This was a completely subjective piece of data, and although interesting, it simply illuminates the personal preference that is the take-home message of this article. Both compounds were proven effective, but tadalafil tended to be preferred. 

compare sildenafil vs tadalafil
Romantic senior man kissing a cheerful woman on cheek

Although the brand-name versions of these ED solutions are rather expensive, the generic versions, which have also been approved by the FDA, are much more affordable through modern treatment options. Telehealth clinics like Invigor Medical are able to have you speak with a medical professional, obtain a prescription, and order your sildenafil or tadalafil from the convenience of your smartphone. This has allowed them to cut the cost down dramatically. Thanks to this, these two compounds are comparable in price as well, leaving one last factor to consider when deciding which treatment option is best for you. Which is more compatible with your lifestyle?

As you now know, sildenafil works more quickly. But due to its smaller window of effectiveness, you will need to take it as close to when you plan to have sex as possible. Tadalafil can be taken once every three days and still potentially be effective. It has the added benefit of not having to worry about whether you have eaten fat or not, unlike sildenafil. Overall, they are both incredibly convenient and effective options for the treatment of erectile dysfunction. Which one is best is going to be up to you. With the ease of access now through telehealth clinics, there is no reason to start taking control of your own health and finding what works for you and your lifestyle.  


While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider.  You should always consult a practicing professional who can diagnose your specific case.  The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice. 


1Pfizer Products, Upjohn Canada. 92020). Product Monograph, Viagra. Retrieved from

2Gong, B., et al. “Direct comparison of tadalafil with sildenafil for the treatment of erectile dysfunction: a systematic review and meta-analysis.International Urology and Nephrology. 2017; 49(10): 1731–1740.

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