Niacin - Cytomel (Liothyronine) Interaction
Herbal: Niacin
Also Known As: 3-Pyridinecarboxylic Acid, Vitamin B3
Drug: Liothyronine
Brand names:
Cytomel
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jul 22, 2023
Interaction Details
Liothyronine is classified as belonging to the following category: Thyroid Hormone
Theoretically, niacin might antagonize the therapeutic effects of thyroid hormones.
Clinical research and case reports suggests that taking niacin can reduce serum levels of thyroxine-binding globulin by up to 25% and moderately reduce levels of thyroxine (T4). Patients taking thyroid hormone for hypothyroidism might need dose adjustments when using niacin.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- O'Brien T, Silverberg JD, Nguyen TT. Nicotinic acid-induced toxicity associated with cytopenia and decreased levels of thyroxine-binding globulin. Mayo Clin Proc. 1992;67(5):465-8.
- Cashin-Hemphill L, Spencer CA, Nicoloff JT, et al. Alterations in serum thyroid hormonal indices with colestipol-niacin therapy. Ann Intern Med. 1987;107(3):324-9.
- Drinka PJ. Alterations in thyroid and hepatic function tests associated with preparations of sustained-release niacin. Mayo Clin Proc. 1992;67(12):1206.
- Shakir KM, Kroll S, Aprill BS, Drake AJ 3rd, Eisold JF. Nicotinic acid decreases serum thyroid hormone levels while maintaining a euthyroid state. Mayo Clin Proc. 1995;70(6):556-8.
Niacin Overview
Niacin, also known as vitamin B3, is a water-soluble vitamin found in a variety of foods, including meat, poultry, fish, and fortified grains.
It plays a variety of roles in the body, including in the metabolism of carbohydrates, fats, and proteins. It is also necessary for the production of energy in the body and in the synthesis of different hormones.
Niacin deficiency is rare in developed countries, however, supplementation has been shown to have several positive benefits. For example, it can reduce the risk of diabetic neuropathy (i.e., nerve pain) and has been shown effective for treating some types of high cholesterol (extended-release niacin is used as a prescription drug in the United States for this purpose).
There is a multitude of niacin forms available as dietary supplements, including NADH, niacinamide, and nicotinamide riboside, all with different properties.
Liothyronine Overview
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Liothyronine is used to treat hypothyroidism (a condition where the thyroid gland does not produce enough thyroid hormone). Liothyronine is also used to treat a goiter (an enlarged thyroid gland) and to test for hyperthyroidism (a condition where the thyroid gland produces too much thyroid hormone). Liothyronine is in a class of medications called thyroid agents. It works by supplying the thyroid hormones normally produced by the body.
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Currently, there is not enough evidence from clinical studies to support the use of liothyronine, alone or in combination with other medications, as the first choice of therapy to treat hypothyroidism.
Niacin - More Interactions
Niacin interacts with 694 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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