letro will kill your libido. I thought that really dose letro would equal arimidex but I was wrong, I used 4 drops on my tounge every day and in a few days my libido was dead. Its not only the amount of estrogen each AI kills but its the profile of which type of estrogen it controls . letro kills all the types of estrogen, the type that help libido and have to do with bloat and gyno but others like aromisin or aifm are geard more towards the type of estrogen that leads to bloat and gyno and and keep the other type that helps libido at reasonable levels. Ofcourse high levels of either one will kill libido but the point is that even with extremely low dose letro my libido was dead