So you have decided that you are going to buy a PDE-5 inhibitor to treat your erectile dysfunction problem, but you are not sure which one would be right for you. The three that you have to choose from are Viagra (sildenafil, Pfizer), Cialis (tadalafil, Lilly/ICOS) and Levitra (vardinafil, Bayer). These three drugs are the only drugs approved by the FDA to treat erectile dysfunction. All three work in the same way to preserve high levels of the substance cGMP (cyclic guanosine monophosphate) that is produced when a man is sexually aroused. As long as there are high levels of cGMP an ample amount of blood flows to the penis and an erection can be sustained. PDE-5 (phosphodiesterase-5) is the enzyme that is responsible for breaking down cGMP, so the idea is to inhibit the introduction of this enzyme when an erection is desired. This can be accomplished with all three of the aforementioned products. However, there are some differences that exist between them that should be considered before you make your purchase.

There has never been a head-to-head clinical comparison of these three drugs, and this is due mainly to the fact that Cialis and Levitra are still relative newcomers to the world of PDE-5 inhibitors. Viagra on the other hand has been on the market for many years, and there have been over 30 million men treated with this drug and thousands of peer-reviewed articles written. Although there has never been an officially recognized comparison with these three drugs together, all three have been studied separately, and the results of these studies have yielded almost identical findings.

First, let's talk about the similarities in these three drugs. The efficacy is approximately 70% with all three. Most men have successful results. Most importantly, they all appear to be safe as long as they are taken while following the proper instructions and guidelines. There are certain similar precautions that should be taken before using any of these drugs.

1. Tell your Doctor:

?About any allergies to medications.

?About any prescription or non-prescription drugs that you are currently taking, as well as any dietary or herbal supplements.

?About any surgeries you are planning to have in the future.

?About any nitroglycerin or long-acting nitrate you are taking for chest pains (may cause dangerously low blood pressure when taken with a PDE-5 inhibitor).

?About any alpha-blockers you are taking for prostate or blood pressure problems (may cause dangerously low blood pressure when taken with a PDE-5 inhibitor).

2. Read the instructions on the label carefully and follow them exactly as instructed.

3. Do not take any of these drugs more than once a day.

4. Ask your doctor or pharmacist to explain anything you do not understand.

The side effects that are associated with Viagra, Cialis and Levitra are pretty much the same. The following side-effects can occur with some men, but they are not common:

?Headache

?Upset stomach

?Flushing (a warm feeling)

?Nasal congestion

?Changes in vision

?Back pain (mostly with Cialis)

Most of the time these side effects are mild, but if severe forms occur it is recommended that you contact your doctor.

If any of the following symptoms occur after taking one of these PDE-5 inhibitor drugs it is recommended that you seek emergency treatment at a hospital:

?Severe rash

?An erection that is painful

?A prolonged erection that lasts more than 4 hours.

?A fainting incident

?Any kind of chest pain

?Burning or itching while urinating

While the differences between these three drugs are subtle, there is one major difference that sets Cialis apart from Viagra and Levitra. The effects of Viagra last about four hours. Levitra lasts about five hours. However, the effects of Cialis on the other hand can last anywhere from 17-36 hours, which is the reason why it is often called ?super Viagra? or the ?weekender? erection drug. A man can take one 10mg pill on Friday and still be experiencing the effects on Sunday. This however does not mean that he will have an erection for the entire weekend. Cialis requires a man to be sexually stimulated to take effect, so an erection will only be obtained when he is thinking about sex. This is also the case with Viagra and Levitra.

There is one other difference that sets Cialis apart from Viagra and Levitra, and it is in the absorption rate. Viagra and Levitra absorb fairly rapidly in the blood stream. It takes between 30-120 minutes for these drugs to take effect. The absorption rate of Cialis is much faster, at about 15-30 minutes. While the absorption rate of Cialis is faster than the other two drugs, they are all highly protein bound drugs (96%). In plain terms this means that they will absorb faster when taken with a high protein meal. If you take them with a meal that has a high fat content, the absorption rate will be reduced.

One side effect that has been reported to occur with Viagra users that does not occur with the other two drugs is a tendency to experience a slight change in vision that causes the user to see things with a slightly bluish tint or hue. This effect goes away once the drug is out of the system.

Viagra, Cialis and Levitra are the best thing that ever happened to any man who is experiencing erectile dysfunction. They are safe, and they are the only PDE-5 inhibitors that are approved by the FDA. The benefits far outweigh the detrimental effects of using one of these drugs. The side effects are usually minimal and mild with most men. As long as these drugs are taken as prescribed following all of the instructions and guidelines closely, there are very minimal negative effects.

? 2005 copyright. Michael P. Connelly