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Cialis and Viagra: Basic Information and Side Effects

Viagra / Cialis / Levitra. These big three blockbuster drugs are only available by prescription and therefore are not supplements. But I wanted to cover them, because they’re as close to a “miracle pill” for anyone struggling with testosterone, libido or erectile difficulties. Viagra is good for four hours and Levitra for six. Cialis, on the other hand, in this category is king: it’s potency lasts for 36 hours. This makes it ideal as it really gets the penis back in shape by increasing early morning erection count, confidence and sexual activity for extended periods of time.

So do you want the good news or the bad news first?  I’ll start with the good news.  Viagra has been found, for example, to help with treatment of high blood pressure in the lungs, cardiovascular performance at high altitudes and may also prevent blood clots, a major cause of heart attacks and strokes. [1]  And Viagra’s long-lasting brother, Cialis, has been found to help men with BPH (Enlarged Prostate). [2]

Need to boost your Nitric Oxide naturally through food, drink and supplements? Check out Lee Myer’s book here: The Peak Erectile Strength Diet

Or do you need the most comprehensive testosterone book in Amazon? Here it is: Natural Versus Testosterone Therapy

So there is actually a lot of good medical news coming out about these drugs and the reason is probably simply the fact that you need Nitric Oxide and all of these drugs help Nitric Oxide to stay in your system longer.  Nitric Oxide does many things to help your body fight heart diseasse (and cancer) and so it should not be overly surprising that in aging males, a little more Nitric Oxide may actually be helpful in the same way that Testosterone Supplementation (HRT) actually helps restore youth to many older guys.

However, I would still recommend caution with these three drugs, becuase of their side effect profile – see below – and because, in general, it is better to solve the root of your erectile difficulties, which is almost always poor heart and endothelial function. Erectile dysfunction can also be related to low testosterone, another condition that you should see a doctor for.

NOTE:  Please read my link on Recreational Use of Viagra and Other PDE5 Inhibitors for additional information.

I recommend that these drugs be used primarily as a bridge to help you get your penile tissue back in shape after months of few morning erections. Furthermore, keep in mind that there are Supplements that are very effective as well for short term solutions.

There’s another reason that I emphasize using these short term if at all possible:  you want to coax your body to actually produce more Nitric Oxide on its own because this is a sign of endothelial health.  The endothelium is the thin lining of your veins and arteries and one of the signs of an injured, out-of-shape endothelium is decreased Nitric Oxide production.  Please, please, please read this link How To Fix Erectile Dysfunction Long Term to find out how to get your endothelium to start pumping out more Nitric Oxide naturally.

By the way, it is also possible that some of the men afflicated were taking too large of a dose. Some men overtake testosterone derivatives, i.e. steroids, quite frequently.  Would it be surprising that some men take too much Viagra during “desperate” situations?  But arguing against that is the fact that all three of these drugs had patients experiencing oxotocity, hearing problems during clinical trials while they were presumably testing dosing and other aspects of bringing this public. Again, talk to your doctor and do your homework.

Also, back in 2000, it looked as if there would be a promising new class of drugs coming out both more potent and with fewer side effects. So far these have not been tested on humans, but the animal studies are looking very good. I have not been able to find if the clinical trial process is making good progress on these drugs or not.

One interesting side note is that researchers have found that Viagra is about 80 X more potent at inhibiting PDE5, the enzyme that indirectly affects Nitric Oxide production, than the primary ingredient in Horny Goat Weed Icariin. However, there are many less side effects with Icariin and Horny Goat Weed, making it an excellent alternative to Viagra depending on the severity of one’s erectile dysfunction.  Researchers are currently taking Icariin and modifying it slightly to see if they can come up with a “new Viagra” with decreased side effects.  Read below for a discussion of the many side effects associated with these drugs:

NOTE:  One recent study showed an increase in testosterone post-exercise in healthy male subjects taking Cialis. [7] So are these PDE5 inhibitors a good idea before exercise?  Unfortunately, the study also showed that Cialis increased cortisol more than normal and, of course, cortisol is definitely not something we want to boost under normal circumstances.  In addition, below I list a number of side effects from Cialis (and Viagra and Levitra as well) that would make using Cialis as a testosterone booster even more questionable.


Now for the bad news or, better worded, cautions:  it is important to note that the FDA is now requiring a warning label on all three of these drugs because there have been 29 cases (at the date of writing this) of sudden hearing loss.  The problem is that there are related PDE5 receptors involved in hearing that these drugs activate. (Viagra has also been implicated in making sleep apnea worse.)  However, the number of men affected by this is small considering the very large number, about 30 million, using these drugs. In fact, Lilly spokeswoman Keri McGrath said a recent Lilly review found about 1.1 incidents of sudden hearing loss per million Cialis patients, which she said was lower than the incident rate in the general population. Nearly 12 million men have been prescribed the drug, the company said. Note: I have also read that Cialis has less of this crossover effect than Viagra. But, again, discuss all this with your doctor if you feel you need to go this route.

The underlying problem with these drugs is that they affect other phosphodiesterases in the body, including the ones that effect hearing, sight and heart function.  For example, Viagra can inhibit the PDE6 inhibitor, affecting the rod and cone photoreceptors in your eyes to a certain extent. One study came out and said there could even be potential damage to the optic nerve. [4] But subsequent studies found no such association. [5]

Another major issue with these drugs are dangerous arrythmias and palpitations.  The problem is that they increase, for reasons not fully understood, the sympathetic nervous system.  One study showed that noradrenaline was significantly increased after taking Viagra, for example, in healthy young men. [6] These fight-or-flight chemicals can be dangerous to the heart as they increase the likelihood of irregular heartbeat (and potentially stroke).

No, the doctor won’t tell you that when he gives you a prescription!  These drugs can cause problems with heart issues and medications so you’ve got to discuss that with your doctor if that is your situation.  Remember:  there are a number of possible side effects from drug combinations with Viagra for example.  You can also potentially get facial flushing, stomach upset and/or heartburn and headaches.

And the most potentially dangerous side effect involves nitroglycerin.  Nitroglycerin, a drug prescribed for heart pain, can result in shock if taken at the same time as Viagra. And, because drugs such as Viagra are worked on by the same liver enzyme, it could raise or lower levels of many other drugs such as ketoconazole and entacapone.

There has been concern that these PDE5 inhibitors should not be prescribed to patients with heart disease or that they could possibly lead to heart attacks.  However, several studies have shown Viagra to be safe in both cases [3], but of course you should also discuss this with your doctor.


1) Proceedings Nat Acad of Sciences USA, 1008, 105:13650-13655

2) J of Urology, 2008, 180:1030-1033

3) BMJ, 2001, 322(7287): 651–652; Archives of Int Med, 2004, 164(5): 514–520

4) Br J Ophthalmol, 2006, 90:154-57, “Non-arteritic anterior ischaemic optic neuropathy and the treatment of erectile dysfunction”

5) J of Sexual Med, 3(1):12-27, Published Online 5 Jan 2006, “Ocular Safety in Patients Using Sildenafil Citrate Therapy for Erectile Dysfunction”


7) The Journal of Clinical Endocrinology & Metabolism, 2008, 93(9):3510-3514, “The Type 5 Phosphodiesterase Inhibitor Tadalafil Influences Salivary Cortisol, Testosterone, and Dehydroepiandrosterone Sulphate Responses to Maximal Exercise in Healthy Men”

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