Ashwagandha and Thyroid

📜 Historical Use

Ashwagandha has been used in Ayurvedic medicine for millennia, classed among the rasayana or rejuvenative herbs, and is still one of the most widely used single herbs in that tradition. Its common alternative name, Indian ginseng, reflects how it has been positioned in Western markets rather than any botanical relationship to true ginseng.

📊 What the Research Shows

Thyroid support is not among the uses the evidence supports. The National Center for Complementary and Integrative Health lists ashwagandha as possibly effective for insomnia and stress in some preparations, unclear for anxiety, and supported by limited evidence for increasing testosterone and sperm quality when taken for two to four months. For asthma, athletic performance, cognitive function, diabetes, menopause, female infertility and COVID-19, the evidence is insufficient. Thyroid conditions appear in the safety section rather than the benefits section — ashwagandha is specifically not recommended for people with thyroid disorders. If you arrived here hoping ashwagandha would treat hypothyroidism or Hashimoto's, the current evidence does not support that, and there is a real possibility of interference with treatment that is working.

If you have a diagnosed thyroid condition, or you take levothyroxine or any other thyroid replacement, the useful answer here is not a dose — it is a conversation with your prescriber before you start rather than after. Adding ashwagandha can shift your thyroid levels in a way that is hard to tell apart from your condition changing, which makes your labs harder to read and your treatment harder to adjust. Do not use it for an overactive thyroid.

Not recommended in thyroid disorders, and not recommended in autoimmune conditions — Hashimoto's and Graves' disease sit at the intersection of both. It can stimulate thyroid function, which is dangerous in hyperthyroidism or iodine-induced thyrotoxicosis, and it may change how much thyroid medication you need. Other reported effects include drowsiness, stomach upset, and liver injury, which has been reported even at ordinary doses.

⚠️ What happens if taken in excess:

Can stimulate thyroid function — dangerous in hyperthyroid conditions or iodine-induced thyrotoxicosis. May change thyroid medication requirements. Same general toxicity as ashwagandha: drowsiness, GI upset, and liver toxicity risk at high doses.

Ashwagandha may interact with thyroid hormone medications — the interaction most relevant to anyone reading this page. If you take levothyroxine or any thyroid replacement, adding ashwagandha risks shifting your levels in a way that is hard to distinguish from your condition changing, and that is a conversation for your prescriber before you start rather than after. It may also interact with diabetes medications, blood pressure drugs, immunosuppressants, sedatives and anticonvulsants. Autoimmune thyroid disease sits at the intersection of two cautions here, since ashwagandha is not recommended in autoimmune conditions either.

1. Ashwagandha — What the Science Says — National Center for Complementary and Integrative Health NIH NCCIH (2026)[NIH ↗]