Hypothyroidism: Can calcium supplements interfere with treatment?

Yes, they can. Hypothyroidism treatment usually involves thyroid hormone replacement medications. They include synthetic thyroid hormones levothyroxine (Synthroid, Unithroid, others) and liothyronine (Cytomel), as well as thyroid extract supplements. Calcium supplements — or antacids containing calcium — can interfere with how the body absorbs those medicines.

The problem happens mainly if you take thyroid hormone replacement and calcium supplements at or near the same time. Follow these steps:

• Don’t take calcium supplements or antacids at the same time you take thyroid hormone replacement.
• Take any products containing calcium at least four hours before or after taking thyroid hormone replacement.

Other supplements — especially those containing iron — also can interfere with thyroid hormone replacement. Some foods and other medicines can too. If you are prescribed thyroid hormone replacement, tell your healthcare professional about all the other medicines and supplements you’re taking.