I take Premarin 3.25....all hot flashes/night sweats stopped after 2nd day...there are cancer warnings about it, so it a personal choice. My CF doc said it won't affect CF. The only thing is, once you start on it...you are on it the rest of your life or everything will come back. I had to do something as over the counter stuff wasn't working and the hot flashes were so bad, I felt like I was cooking my brain and thinking at work was almost impossible. Again, it is a personal choice. I have been on it for over 12 years.