well,if you can build a tolerance,i'm screwed.we could probably switch from viagra to cialis to levitra,to avoid any kind of tolerance.but probably there will be a new and improved e.d. medicine before any of us build any REAL tolerance to these medications.so i think men for many more hundreds of years to come will never have to worry about not being able to get it up.hell,they might even have a cure for it before too long!!

I can not locate any information that says one can or does over a period of time build up a tolerance to the active ingredients of Viagra.

I did find a lot of 'interesting' warnings on it.

I will go out on a limb and say that if you abuse or over use it your body might build up some tolerance to it, meaning its effect may suffer or you might have to take more in order to reap the rewards.

I would also theorize that if you do not need it and do use it that it could lead to ED. I infer that from all of the interesting warnings I have read.