Can I Take These?

Can You Take Ashwagandha and Levothyroxine Together?

Ashwagandha is named directly by NCCIH as a supplement that may interact with thyroid hormone medications like levothyroxine, and is specifically cautioned against for people with thyroid disorders.

MonitorEvidence: Moderate

See the full Ashwagandha page and Levothyroxine page for other reviewed interactions and reference information.

What the interaction means

NCCIH's ashwagandha fact sheet states: "There is evidence that ashwagandha might interact with some medications, including... thyroid hormone medications," and separately: "Ashwagandha is not recommended for... those who have autoimmune or thyroid disorders." A published case report (Kamal et al., Cureus 2022) documents a 73-year-old woman who stopped levothyroxine and used ashwagandha root extract instead, developing thyrotoxicosis that resolved after stopping ashwagandha; the authors note ashwagandha "stimulates the synthesis and/or release of T4 at the glandular level." A 2026 Phytotherapy Research review states ashwagandha's "endocrine-modulating activity... has been implicated in thyrotoxicosis and adrenal suppression."

Why it may happen

Ashwagandha appears to have its own effect on thyroid hormone levels (stimulating T4 synthesis/release and, in case reports, causing thyrotoxicosis), which could compound with or complicate levothyroxine dosing in someone being treated for a thyroid condition.

Practical context

The case report describes ashwagandha used as a substitute after levothyroxine was discontinued, not literally taken at the same time as levothyroxine -- no directly-read report of concurrent combined use was found. Still, because NCCIH names thyroid hormone medications as an interacting class and separately advises against ashwagandha in people with thyroid disorders, anyone on levothyroxine should discuss starting ashwagandha with the prescriber managing their thyroid treatment, and watch for symptoms of thyroid hormone excess (palpitations, weight loss, heat intolerance, tremor).

What the sources say

Potential Adverse Effects of Ashwagandha: A Critical Review of Preclinical and Clinical Evidence — Phytotherapy Research (Wiley)Levothyroxine Sodium Capsules — FDA Prescribing Information — YARAL Pharma, Inc. (via DailyMed, U.S. National Library of Medicine)Ashwagandha — National Center for Complementary and Integrative Health (NIH)Ashwagandha as a Unique Cause of Thyrotoxicosis Presenting With Supraventricular Tachycardia — Cureus (PMC, National Library of Medicine)

Last reviewed 2026-08-24

Medical information disclaimer: this information is general and educational. It does not diagnose conditions, prescribe treatment, or determine whether a combination is safe for you personally. Follow your prescription label and ask a pharmacist or clinician before starting, stopping, or combining products. Full disclaimer.

Related interactions