Synthroid, a brand name for the synthetic thyroid hormone levothyroxine, is a commonly prescribed thyroid medication. Many people taking this drug must also take a calcium supplement to help them avoid bone loss. Because of the interaction between Synthroid and calcium, it is essential that you carefully follow your doctor’s instructions on when and how to take both your thyroid medication and calcium supplement.
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Synthroid should be taken on an empty stomach, so doctors generally instruct patients to take this medication immediately upon waking. After taking Synthroid, you should not eat or drink anything other than water for a least 30 to 60 minutes. Maintaining a day-to-day regimen in taking this drug helps keep the level of thyroid medication in your system constant, an important factor in feeling well.
Calcium and Synthroid Interaction
Calcium carbonate has a “modest, but significant” effect on the ability of your body to absorb thyroid hormone medication, according to a study reported in "Journal of the American Medical Association." If you take Synthroid concurrently or within a few hours of taking a calcium supplement, you risk reducing the effectiveness of the hormone drug. Calcium binds and delays or even prevents the absorption of Synthroid, making it more difficult for your body to take up the medication.
Dangers for Hypothyroid Patients
Taking Synthroid and calcium at the same time, or too close to the time as taking calcium, can potentially cause problems for a patient with hypothyroidism, particularly if her usage of calcium is sporadic or inconsistent. If your calcium intake habits prevent your medication from being properly absorbed, you may begin to experience the same hypothyroid symptoms -- including fatigue, constipation, dry skin and elevated blood cholesterol -- that required you to take the drug in the first place. Inconsistent calcium use can also throw off blood tests, making it difficult for your doctor to determine the correct dosage of Synthroid required to maintain your health.
Dangers for Cancer Patients
Taking Synthroid and calcium too close together or at the same time can have a potentially dangerous effect on a thyroid cancer patient's treatment. For such patients, doctors typically prescribe thyroid hormone at a slightly higher-than-normal level. Such a dosage is intended to suppress the patient’s TSH, or thyroid-stimulating hormone, levels to help prevent the growth or recurrence of any cancer cells. If you make any changes in your medication or supplement routine that affect the absorption of Synthroid, you may unwittingly alter the level of your therapeutic dosage.
Recommendations for Taking Synthroid and Calcium
By allowing at least 4 hours to pass between the time you swallow your Synthroid and the time you take your calcium supplement, you can greatly reduce any risks of lessening the effectiveness of your thyroid medication. Keep your doctor informed of any changes you make in your daily supplement routine.