Can You Take L-Carnitine and Thyroid Glandular Together?

Dose or timing may matter

The short answer

L-carnitine inhibits thyroid hormone entry into cell nuclei and may reduce the peripheral action of T3 and T4. This peripheral antagonism may reduce the effectiveness of thyroid glandular supplementation.

How to arrange timing

Consult a healthcare provider before combining L-carnitine with thyroid support supplements.

Reference

Reference noted for this combination: Benvenga S et al. Usefulness of L-carnitine as a naturally occurring peripheral antagonist of thyroid hormone action. J Clin Endocrinol Metab. 2001;86(8):3579-3594

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.