How to Take Vitamin D With Synthroid

Vitamin D pills lined up.
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Your body makes its own vitamin D and you also get it from dairy sources and supplementation. Vitamin D stimulates your bones to absorb calcium and also helps control your blood pressure. Synthroid is a synthetic form of the thyroid hormone prescribed for a condition known as hypothyroidism. Individuals with hypothyroidism may also exhibit lower than normal vitamin D levels, according to Theodore C. Friedman, M.D., Ph. D., author of "Vitamin D Deficiency and Thyroid Disease." Current literature shows no adverse interactions between synthroid and vitamin D; however, because you are taking a prescription medication, take precautions when taking other drugs, supplements or vitamins.

Step 1

Consult your endocrinologist before starting your vitamin D regimen. Your endocrinologist can advise you of any precautions you should take regarding combining the vitamin D with your synthroid.

Step 2

Take your synthroid per your endocrinologist's instructions. Your doctor may prescribe one daily dose or multiple doses spread throughout the day.

Step 3

Take at least 1,000 IU of vitamin D daily, unless your physician directs otherwise. The maximum safe dosage, or tolerable upper intake level, is 4,000 IU.

Step 4

Work with your doctor to monitor your thyroid function and serum vitamin D levels. Your doctor may make adjustments to your synthroid or vitamin D dosage, if necessary.


Consult your physician immediately if your hypothyroidism symptoms worsen, such as sensitivity to cold, fatigue and joint pain as well as depression, constipation and muscle weakness.