Zytiga reduces the amount of cortisol in your body, prednisone, offset that. If you don’t get enough prednisone to offset the cortisol reduction, then you get a lot of fatigue. I was at a prostate cancer seminar a couple of months ago where a doctor talked about his prostate cancer. he was having terrible fatigue problems so he increased his prednisone from 5 mg to 7 1/2mg and that resolved his problem with fatigue. I’ve been working with someone who would get out of bed and need to go back to sleep for three more hours because the fatigue was so bad. I asked him to talk to his oncologist about increasing his prednisone. He was told to increased it from 5 mg to 10 mg a day. It made a major difference in his fatigue. Some doctors recommend 10 mg as the initial dosage. Be aware that the drugs can also cause diabetes. Keep track of your A1c or fasting blood sugar to make sure you don’t have a problem with becoming prediabetic.

I had seven weeks of radiation and never had any problem with fatigue from it. Results will vary, some people do feel fatigue. I was on Lupron for 7 years so I got to “enjoy” all the issues it causes.

One solution to the fatigue is exercise. Get out there and walk at least a couple of miles a day. If you can do some weightlifting or at least exercises that involve weights that really helps and also offsets the muscle deterioration caused by Lupron. Those two things seem to help people the most to relieve the fatigue issue.
Don’t be surprised if Lupron causes you to get a belly or a larger belly, if you can weigh yourself every day and base what you weigh on what you eat it can reduce that belly fat but it occurs a little due to stomach muscle loss. Doing a lot of sit ups might also offset some of the belly fat issues.

As for hot flashes, I had severe hot flashes for the first year on Lupron. As a hot flash was hitting I would feel a lot of fatigue. After a year, my oncologist prescribed a depo-provera shot every three months and it really stopped those hot flashes on Lupron. There are other hormones that can do this, speak to your doctor.
I know one person that says eating tofu every day really controlled his hot flashes, another person in this forum said the same thing. Can’t hurt to try it.

Another thing you will notice after being on the Lupron for a while is brain fog. If you were going to ask a question and all of a sudden you forgot the details, names don’t come to you, you may remember all the facts about something, but can’t remember the names or other involved details. It can be frustrating.

Just a number of things to be aware of when starting these drugs.