What is the dosage for Viagra, every day or every time before sex?

Why would you possibly want to do that? Sildenafil is Rxed exclusively to enable a man to get erections and its better to start with a lower dose . Maybe 25 mg will work for you or you can break a 100 mg tab and take half of it ~ which is what I do. If you don't need it to get an erection its not advisable to take it, your body might develop a dependency on it to obtain an erection if you take it too often when you don't need it.

I've used Viagra for over 10 years and found it takes me about 45-50 minutes to work but if you take a Tagamet (cimetidine) tablet or two before or with the Viagra it will last much longer than 3-4 hours. I've had it last up to 6 or 7 hours

Thank you as I no longer live in the states, for sometime now, I did not know..see one learns something new everyday... thank you my friend for educating me.

Here in Chile, you must have a prescription.

All the best..you are a star

Sorry to disagree with you Sacosam but in the U.S. you need a prescription to buy (real) Viagra. There are plenty of fakes on the internet but there are not sildenafil or genuine Viagra. The patent will run out on Viagra I believe in 2017 so hopefully there will be less expensive Viagra available. They were supposed to come out with a faster acting sublingual but I haven't seen it on the market yet.

Viagra, ( must ) be prescribed by your doctor, Do not use if you have a heart condition. If one is given Viagra, he the male ( must ) be sexually stimulated at or on the 25 mts time . This is totally important , you must take the Viagra , then after 25 to 30 mts sexually stimulate, or the Viagra will not work, it will be useless.. and you will have wasted your money, also , it may only be taken every three days, not daily , so a ten mg tablet may be not strong enough if you are a big build, 20 can be used, but only once a week, the time this will work will be up to 12 days, no more. Be aware Alcohole is not recommended.