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Thyroid UK
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Affects of levotyhroxine and anastrozole for breast cancer

Does anyone know if it ok to take levotyhroxine and anastrozole together.

I am getting very conflicting advice from my oncologist and GP.

I had mastectomy nearly 2 years ago and ended up in hospital during chemo and nurses kept giving me all my tablets together in morning, along with my folic acid tablet and vitamin D tablet.

Reading your blog, I notice people seem to take thyroxine at night.

I'm tired of trying to get a sensible answer to a simple question. If my oncologist and GP don't know, who does.

I so want to survive and need to make my tablets work properly.

Please can someone help me?


4 Replies

I hope you are taking large enough dose of vitamin D3 (with K2) as research shows it will help fight breast cancer. Lots of sunshine would be best.

This paragraph from Wikipedia talks about counters to Levo:

There are foods and other substances that can interfere with absorption of thyroxine. Examples include calcium and iron supplements taken within 4 hours of levothyroxine,[12] as well as soy products within 3 hours of the medication. Other substances that reduce absorption are aluminium and magnesium containing antacids, simethicone, sucralfate, cholestyramine, colestipol, and polystyrene sulfonate. Grapefruit juice may delay the absorption of levothyroxine, but based on a study of 10 healthy people aged 20–30 (8 men, 2 women) it may not have a significant effect on bioavailability in young adults.[13] A study of eight women suggested that coffee may interfere with the intestinal absorption of levothyroxine, though at a level less than eating bran.[14] Certain other substances can cause adverse effects that may be severe. Combination of levothyroxine with ketamine may cause hypertension and tachycardia;[15] and tricyclic and tetracyclic antidepressants increase its toxicity. On the other hand lithium can cause hyperthyroidism (but most often hypothyroidism) by affecting iodine metabolism of the thyroid itself and thus inhibits synthetic levothyroxine as well.[citation needed]


I can't thank you enough for replying, it's awful when you feel so alone.

Do you know where I can get D3 from? My oncologists keep telling me not to take anything without consulting them.

I have to take codeine/paracetamol for the joint ache - made worse now because of the hormone tablet.

I just wish they had taken both breasts off as I constantly worry about it spreading.

I think my hysterectomy had a lot to do with getting cancer.

Bless you and thanks for taking the time for me


Most, but not all, over-the-counter vitamin D these days is D3.

You can get it from Amazon or numerous other on-line suppliers.

Or from the USA:


D3 is also called cholecalciferol:




I'm so sorry about your predicament. I'm putting a link in that talks about D3 and breast cancer; actually almost any form of cancer either is found to be deficient in vitamin D or causes the deficiency.

I do enjoy Dr. Mercola's articles even though he does sell products he often produces good evidence and/or research to back up his theories.

I think you feel you have no control which makes you feel helpless. The best thing is to learn as much as you can about your condition if you are up to it. There are even types of breast cancer that would never have spread even without surgery.

This is the article about D3.



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