For example, Levitra is the drug uses a smaller dose, but starts working faster than Viagra.  It is known that Viagra works for about 4 or 5 hours, but it can also be effective up to 12 hours taking into account individual peculiarities of every person. Levitra’s action lasts for about the same time, but Cialis has a great advantage over the other two drugs: it remains effective for 24 hours and even up to 36 hours for different patients, which is why it got the nickname, “the weekend pill”.

Each pill has its own advantages and yet almost all the drugs have side effects too. The well-known Viagra, the same as Levitra and Cialis can cause headaches, upset stomach, flushing, vision tint and a stuffy nose.  Yet Levitra seems to have fewer or at least less strong side effects. But it all depends on the individual qualities of health and organism of every patient.  You should also remember that before you begin to take one of the 3 medications for ED, you should also consider lifestyle factors that may play a role in your ED, such as exercise diet and smoking.

The phentolamine just relaxed a muscle.  Starting in the mid-1980s, it became common for men with erectile dysfunction to inject smooth-muscle-relaxing drugs as a treatment for the problem.  But today, Viagra makes the process easier by using a pill instead of an injection and Viagra only causes an erection when the man is sexually aroused (Phentolamine in contrast, causes an immediate and uncontrolled erection).

So how can you give a man an erection with a pill? What you need is a drug that acts only on the smooth muscle in the arteries of the penis and the penis is one of the places in the body where the brain needs to be able to turn the blood flow on and off with a valve. Let’s start with the basic concept: how does the brain control blood flow to different parts of the body? In the human body, the “valves” open and close using muscles in the walls of arteries and when these muscles relax, the arteries open up and blood flow increases. The valves respond to chemical messages that the brain can control, a mechanism that brain uses it to increase blood flow in several different parts of the body. Finally, another enzyme called phosphodiesterase (PDE) deactivates the cGMP; ¬Viagra eliminates the PDE that is decomposing the cGMP, so cGMP builds up in the penis and has a greater effect on the arterial walls. The greater the amount of cGMP the greater the blood flow, and the greater the blood flow, the stronger the erection.

Since the original creation of  brand name Viagra, many other forms of the drug have emerged. Other Sildenafil powered drugs available on the market  include, Genegra, Viagra Oral Jelly, generic Viagra and Kamagra.