Comparing Tadalafil (Generic Cialis) and Sildenafil (Generic Viagra)

When patients come to us looking for relief from their erectile dysfunction, they are faced with a preliminary decision of which medication, tadalafil or sildenafil, is better. Back in the day, when these medications were still on patent AND named Cialis and Viagra, respectively, they were very costly. These were the days of fighting with and often losing to insurance companies. Now that generics are available, so many more people can take advantage of these great, highly effective drugs. We often suggest that patients taking ED medications for the first time try both separately to see which works best for them with the fewest side effects. Ultimately, with prices as low as they are, there’s little financial risk in seeing which is best for our patient’s unique circumstances.

Comparing the Mechanism of Action

Regarding how sildenafil and tadalafil work, they are very similar in that they are both PDE-5 inhibitors. This means they slow or stop the action of the phosphodiesterase type five enzyme in the body. This mechanism increases blood flow to the penis when a man is aroused. It’s worth noting, however, that these medications do not increase sexual desire. Instead, they allow the penis to better fill with blood and achieve a satisfactory erection. With both of these drugs, however, patients must realize that they do not have 100% success and that the success rate has a lot to do with the severity of ed. Also, patients must understand that it is normal to have to increase one’s dose as the problem of ed progresses and that nearly all patients that had initial success with ed pills will eventually lose that degree of success and may need other help.

Comparing Which Works Faster

Both drugs take approximately 30 to 60 minutes to begin working and allow patients to achieve the erection they expect. Peak concentration in the blood is reached after two hours for tadalafil and about one hour for sildenafil. As such, we always suggest taking medication about an hour or two before sexual activity. The time it takes for the drug to function will vary between patients, so use prior experience as a guide.

Of note, sildenafil, a generic Viagra, can be somewhat inhibited after eating a large meal containing fatty foods, and this is not a concern with tadalafil (generic Cialis). We often suggest sildenafil for married couples or long-term partners with a more predictable sex life. Cialis may be more appropriate for patients who are dating, as the big meals often associated with early dating can cause sildenafil to be less effective.

Comparing Which Lasts Longer

Regarding which medication allows an erection to last longer, the clear winner is tadalafil. Sildenafil remains effective for four to six hours, while tadalafil will enable patients to achieve erections up to 36 hours after ingestion, an effect usually seen in younger patients or lesser degrees of ED. In both cases, the drug does not increase desire, instead allowing for a better erection when the desire is present.

Comparing Side Effects

As with any medication, side effects are associated with both sildenafil and tadalafil. Generally, however, both drugs are well tolerated and have few severe side effects.

Patients taking sildenafil may experience headaches, nausea, flushing, stuffy nose, and on occasion, indigestion, or dizziness. Patients may also develop a blue hue to their vision. Most of these side effects are transient and will disappear after stopping the drug. Loss of vision is a potentially severe side effect of sildenafil in certain very rare clinical situations, and you should stop the drug and get medical help immediately if this occurs, as this can, in very rare cases, lead to permanent blindness. Patients with certain eye problems, cardiovascular and metabolic diseases (high cholesterol, high blood pressure, and type 2 diabetes), and smokers may be at higher risk.

Patients taking tadalafil have a slightly different side effect profile. Like sildenafil, tadalafil can cause headaches, indigestion, and nasal congestion. However, tadalafil can also cause unique symptoms like back pain, cough, and upper respiratory tract infections.

Interestingly, while both drugs have side effects, recent studies have shown that they may reduce the risk of early death from heart disease by up to 25%. This does not make them a treatment for heart disease, nor does it replace any therapies you may currently be taking for cardiovascular issues.

Both drugs have a relatively mild risk profile. It is worth noting that any side effects experienced from tadalafil will typically last longer because the drug remains in the bloodstream significantly longer than sildenafil.

Comparing Drug Interactions

If you’ve been prescribed ED medication in the past, or if you are looking for a prescription now, you will undoubtedly be asked whether you take nitrates. Nitrates like nitroglycerin can cause a sudden drop in blood pressure and even lead to heart attack or stroke. Patients on nitroglycerin typically have serious cardiovascular issues that make taking ED medication risky in the first place. Patients taking recreational “poppers,” including amyl nitrate, amyl nitrite, and butyl nitrate, should not take ED medication. Speak to your doctor or pharmacist about other drug interactions to ensure safety when taking your ED meds.

Does Either Medication Reverse ED?

Dr. Engel likes to analogize erectile dysfunction to a roller coaster. Typically, there is a slow movement toward ED. However, once erectile dysfunction begins interfering with sexual activity, it is a downward slope that generally cannot be reversed. Erectile dysfunction medications help improve blood flow to the penis at least transiently. However, the underlying vascular issues associated with ED typically worsen with age, and there’s simply nothing we can do about it. As such, eventually, these drugs will no longer offer satisfying erections, at which point we need to consider further treatments, including injections or penile prostheses (implants).

Which Makes You Harder?

While both drugs offer about the same quality of erection, slightly more men achieved a satisfactory erection with sildenafil, according to a study.¹ However, as mentioned above, tadalafil remains in the bloodstream longer and, in the same study, was preferred by more men, probably for that reason.

The Bottom Line

With generic prices as low as they are, Dr. Engel believes that there is no single erectile dysfunction drug that should be prescribed to every patient. As mentioned above, each drug has its unique benefit and risk profile, which should be discussed during your consultation. With prices as they are, most patients can safely order both sildenafil and tadalafil to see which works best for them. Of course, if you experience any side effects with either drug, stop and switch to the other medication. If the side effects are severe or long-lasting, seek prompt medical attention.

Reference:

1Doggrell SA. Comparison of clinical trials with sildenafil, vardenafil, and tadalafil in erectile dysfunction. Expert Opin Pharmacother. 2005 Jan;6(1):75-84. doi: 10.1517/14656566.6.1.75. PMID: 15709885.