I was on levo and tamoxifen. It felt like I was dying - I would sleep for 16 hours a day and still feel exhausted, every joint in my body hurt, my weight was rocketing. Nobody would listen... my doctor told me it was normal to feel depressed after what I'd been through and my oncologist just shrugged.
I started searching the net for ideas/suggestions/reasons and found a few references to levo being taken alongside tamoxifen and it causing an increase in side effects (hypothyroid symptoms are similar to tamoxifen side effects).
I didn't want to stop taking tamoxifen and I couldn't stop taking levo so I started to research any possible alternatives. My opinions for an alternative to tamoxifen were limited due to being pre menopausal and having an unsympathetic oncologist so I delved deeper into thyroid research. I came across an alternative to levo called Natural Dessicated Thyroid. NDT was the routine treatment for hypothyroidism until the mid 70's when levo became more popular due to it's cheapness. Unlike levo which only contains the t4 thyroid hormone, NDT contains both t4 and t3. T3 is arguably more important as t4 is purely a storage hormone, converting to t3 (the active hormone) as and when our bodies need it. Some people have difficulty converting their t4 into t3 so no matter how much levo you take, you will still feel like hell. In the UK, doctors rely on the tsh test for hypothyroidism which doesn't actually tell them anything about the t3 in our system so the tsh test will come back normal even if you have no working thyroid hormone.
I asked my doctor for separate tests for t3 and t4. Sure enough my t4 was great (as I was taking levo) but my t3 was right at the bottom of the healthy range. I switched from levo to NDT and started to feel better within 3 days. 6 months later I had lost 56lbs, no longer slept half of the day, had significantly less joint pain and far more energy. My t3 levels are now near the top of the range.
There is some research to suggest that radiation therapy for breast cancer can damage the thyroid (thyroid cancer risk increases after breast cancer radiation therapy). I wonder if this is what caused my problems, it's certainly something worth thinking about...

I am tired can fall asleep but can't star asleep for more then a few hours.. I am on Tamoxifen as well. Don't have the energy I use too.. Makes me crazy. I love on a small homestead with chickens and turkeys. I also work full time..Could not keep up on my garden, nor my fencing needs....

I have been on tamoxifen for over a year and have recently felt more tired than normal. I also noticed the manufacturer has changed for tamoxifen so I switched back to my original manufacturer (each manufacturer uses different inactive ingredients). I switched and take tamoxifen in the evening with dinner and found that works best for me. I also take levothyroxin (hashimotos).

What is lexapro?

Try lexapro I call them my happy pills