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Thyroid Preparations

Thyroid Preparations

Generic and Trade Names:

LevothyroxineLevothroid, Levoxyl, Synthroid
Thyroid DesiccatedArmour Thyroid


Thyroid preparations are available in natural and synthetic formulations. Usually the synthetic form is more commonly used. The synthetic types are available as T4 (levothyroxine), T3 (liothyronine) or a 4 to 1 mix of both(liotrix). Thyroid hormone is indicated for hypo-thyroid disorders. (Facts and Comparisons 1999)

Nutritional Considerations:

Take on an empty stomach before breakfast, to increase absorption. (Pronsky 1999)

Avoid alcohol. (Pronsky 1999)

May increase sugar levels, caution with diabetics. (Pronsky 1999)

May cause apetite changes or weight loss. (Pronsky 1999)

Iron may reduce absorption (Beard 1990).

Separate calcium supplements from thyroid agents (Pantazi, 2000)

Avoid soy products together with thyroid hormones because it could reduce absorption of the drugs. (Jabbar 1997)

Herbal Considerations

Red yeast, which contains the active ingredient lovastatin can interact with thyroid preparations. (McKevoy 1998)

Horseradish may interfere with hypothyroid drugs. (Newall 1996)

Bugleweed may interact with thyroid hormones and should not be used together. (Brinker 1998)


Beard JL, Borel MJ, Derr J. Impaired thermoregulation and thyroid function in iron deficiency anemia. Am J Clin Nutr 1990;52:813-19.

Brinker, Francis Herb Contraindications and Drug Interactions, Eclectic Medical Publications, 1998.

Facts and Comparisons, Clinisphere 2.0, Wolters Kluwer Company, 1999.

Jabbar MA, Larrea J, Shaw RA. Abnormal thyroid function tests in infants with congenital hypothyroidism: The influence of soy-based formulas. J Am Coll Nutr 1997;16:280-82.

McKevoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-care Professionals. London: The Pharmaceutical Press, 1996

Pantazi H, Papapetrou PD: Changes in parameters of bone and mineral metabolism during therapy for hyperthyroidism, J Clin Endocrinol Metab 2000 Mar;85(3):1099-106

PDR (Physicians Desk Reference). 49th Edition. Medical Economics Co. Montvale, NJ. 1995.

Pronsky, Zaneta. Food Medication Interactions. 11th edition. 1999.

The Medical Letter Handbook of Adverse Drug Interactions, 1995.


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