Painless Thyroiditis by Withania somnifera (Ashwagandha)

Abstract

The Withania somnifera, also called Ashwagandha, is available everywhere in the world. We present a rare case of thyrotoxicosis following Ashwagandha administration, specifically painless thyroiditis (PT) in this report. The patient was a 47-year-old previously healthy Japanese man, who started taking Ashwagandha two months before his first visit to our hospital. He visited our hospital for typical thyrotoxicosis symptoms like a sense of fatigue, fever at night, and weight loss followed by diarrhea and headache. Blood tests disclosed thyrotoxicosis. Thyroid ultrasonography showed internal echo heterogeneity and no increase in blood flow. Thyroid scintigraphy revealed a deficiency in thyroid uptake. Based on these findings, he was diagnosed as PT. After stopping the administration of Ashwagandha, both his symptoms and serum thyroid markers were improved. This report may spark important debate about whether ashwagandha is safe among healthy people, especially in thyroid toxicity.

Keywords: ashwagandha (withania somnifera); drug-induced thyrotoxicosis; painless thyroiditis; subacute lymphocytic thyroiditis; thyrotoxicosis.

Figure 1. The result of thyroid ultrasonography.

Thyroid ultrasonography (US) showing slightly enlargement of thyroid gland and internal heterogeneity (A: right lobe, B: left lobe). Color flow Doppler enhancement of the US images showing no increase in blood flow (C: right lobe, D: left lobe).

Figure 2. The result of thyroid 99mTcO4 scintigraphy.

Thyroid ^99mTcO₄ scintigraphy showing almost no uptake in thyroid gland (arrowheads).

Figure 3. Schema of clinical course in our case.

The initial visit to our hospital was defined as day 0. Symptoms were developed after taking Ashwagandha and recovered after stopping it. The levels of thyroid marker showing in this schema including free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH). After stopping administration of Ashwagandha, FT3 and FT4 were decreased within reference range.