Thyroid UK
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Why can`t I take calcium supplements with thyroxine?

Iv`e been on Levothyroxine for almost 2 months now, & I`m a bit worried about the fact that your`e not supposed to take calcium supplements, or antacid medication. I`m a bit worried about this because I don`t want to be calcium deficient, & also, what can I take for heartburn, because according to the leaflet that comes in the packet, I can`t take acid supressants either. Why is this?

3 Replies

Calcium stops you absorbing the levothyroxine.

In that sense, it is only necessary to separate taking calcium (including milk, cheese, etc.) from taking levothyroxine by sufficient time. Ideally a few hours.

Many people eventually find that they suffer from heartburn as an effect of their hypothyroidism. If that is the case, it often resolves when you get properly treated with thyroid hormone.

Heartburn/acid reflux can be caused by weakness of the lower oesophageal sphincter - the muscle at the bottom of your food pipe - which fails to work efficiently when hypothyroid. It can also be caused by inadequate stomach acid rather than too much. Both often improve with thyroid hormone treatment.


Hi hairyfairy, If your calcium is on prescription, then ideally your GP should have explained not to take it for at least four hours after taking your levothyroxine. Unfortunately, many GPs don't know these simple facts and we are left to figure it all out the hard way.

You can take daily calcium but it must be well away from thyroid medication. For example, if you take your levothyroxine first thing in the morning, maybe you could take your calcium at night. I've actually heard some people say that taking calcium at night helps them relax and sleep better.

If you haven't been prescribed the calcium and are just taking an over the counter supplement, then it might be a good idea to stop taking it until you can check with your GP about whether or not you really need it. Most people are able to get all the calcium they need from their diet, and too much calcium is not through supplements is not good for you if you're already getting what you need.

Acid suppressants will also inhibit absorption of levothyroxine if taken too close in time. So again, if you really need heartburn relief, try to leave several hours between taking the levo and taking the heartburn relief.


I am on calcium supplements twice daily due to hypoparathyroidism and just make sure I leave 4 hours between taking calcium and thyroid replacement. It states this in the literature which comes with the calcium and my GP was not aware of this.


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