Last Updated on September 29, 2020 by Douglas C. Goldberg, MD
It is known that the maximum dosage of the original Viagra is 100 milligrams of sildenafil.
The maximum dosage of branded Cialis is only 20 mg of tadalafil.
However, can these dosages of two drugs be considered equal in terms of the strength of the effect?
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Viagra vs Cialis: What’s the Difference?
We’ve thoroughly analyzed these drugs and decided to highlight key factors of differentiation.
Genuine Viagra is manufactured by Pfizer Inc., a renowned American pharmaceutical company. Original Cialis is produced by Eli Lilly, which is also a US-based pharma giant.
However, this difference is not determinative in case of generics. They are produced by less-known Indian, Canadian, and European manufacturers. We would not advise to buy generic drugs from China, as a risk to get a counterfeit is elevated.
- Viagra comes in three main dosages: 25mg, 50mg, and 100mg.
- There are four versions of Cialis: 2.5mg, 5mg, 10mg, and 20mg.
As you can see, even the minimal dosage of Viagra (25mg) has less pharmaceutical substance than the maximal-dosed Cialis version (20mg).
Viagra is supplied as a diamond-shaped blue pill while Cialis is sold in the form of almond-shaped yellow-colored pills. In case of generics, the difference may be another (depending on the product you choose).
Viagra and Cialis are both used to treat erectile dysfunction. In addition, other drugs with their active agents are used to fight pulmonary arterial hypertension. These are Revatio (sildenafil) and Adcirca (tadalafil). What is more, there are perquisites to assume that Viagra may be also used for urinary symptoms of BPH, however, there is no official approval for such a purpose.
Viagra works for 4-6 hours, in some males the needed effect may be observed within a 12-hour period. Cialis acts much longer (see below).
There may also be other differences, but they are not significant.
What is the Key Feature of Cialis?
The main advantage of Cialis is an increased biological half-life of the active substance, which is approximately from 17 to 20 hours. Due to this, the desired effect is guaranteed within 36 hours after consuming the pill. As we have noted above, the maximum possible period of action of Viagra is only 6 hours (rarely 12 hours). Interestingly, this advantage is achieved without the use of a higher dosage of tadalafil.
For one and a half days, Cialis (or tadalafil) suppresses the production of PDE5 enzyme in the body, causing the cessation of erection. This drug, as well as Viagra, is a selective PDE5 inhibitor.
What does it mean?
Cialis blocks PDE5 (phosphodiesterase type 5) enzyme more actively, virtually not affecting the rest of useful PDE enzymes.
For example, PDE3 is involved in cardiac muscle contraction, vascular smooth muscle and platelet aggregation. The effect of Cialis on this enzyme is 10 thousand times weaker than on PDE5.
Cialis 20mg vs Viagra 100mg: What’s the Best Choice?
These drugs belong to the same family – PDE5 inhibitors.
They also have about the same efficiency: they work in 80-90% of patients with the highest possible dosage.
- However, Cialis is believed to have either a more concentrated or more potent substance, so it contains a lower dosage than its main competitor.
- However, Cialis 20mg and Viagra 100mg are almost the same in terms of improving erections.
Some may get the best effect from Cialis, while others may prefer Viagra. But do not think that Cialis in the 20-milligram dosage is weaker than Viagra and vice versa.
You might be interested in the following article: Can you improve your libido using Viagra?
Conclusion
Thus, in terms of dosage strength, these doses can theoretically be considered identical. But at the same time, they cannot be fully equated. Cialis has a different half-life, which makes its action time six times longer than that of Viagra (sildenafil lasts up to 6 hours, while tadalafil provides the desired effect up to 36 hours).
So choosing one or another preparation is generally a matter of taste. Administering other medications may also influence the choice, since Cialis lasts longer in the body, consequently, the period of possible harmful interactions with other drugs becomes longer.
I’m an Oncologist and Hematology Specialist primary located in Bryn Mawr, Pennsylvania. I have over 55 years of experience in the medical field and more than 20 years of practice. I’m skilled at the treatment & diagnosis of a large array of ailments & diseases in adults.
Board certifications
- American Board of Internal Medicine Certification in Internal Medicine
- American Board of Hematology Certification in Hematology
- American Board of Medical Oncology Certification in Medical Oncology
