I have been on testosterone replacement since 2008. If I stop applying the gel my own system does not make any testosterone. That is what I did. I stopped applying my testosterone gel and 60 hours later after it is out of my system and skin no more Testosterone levels. Much faster than a Lupron shot which can take up to three weeks to kill your testosterone. I knew this would happen because I went off once before with my endocrinologist because she wanted to see if I really needed it. Then just before a blood test a few years ago I tried it for 60 hours before my blood draw and my T levels were 18. I have every blood test record of mine on a spread sheet going back to 2008.