Are you planning to take it to reduce cortisol levels, and if so, have you had lab tests which confirm elevated cortisol levels? Some herbs have pharmacological effects comparable to synthetic drugs, and you wouldn’t self-medicate yourself with those. Ashwagandha is probably safe, but if your self-diagnosis is inaccurate, it won’t help.
Many of the symptoms of high cortisol mirror those of low cortisol, so it’s helpful to get the labs to point you in the right direction. A 24-hour saliva cortisol test, which involves taking 4 samples throughout the day, can fairly accurately gauge adrenal function. Thyroid problems are usually interlinked with adrenal problems, either because the adrenals interfere with thyroid hormone metabolism in otherwise euthyroid people, or because lack of thyroid function forces otherwise healthy adrenals to compensate.
Lab testing may be cost prohibitive for some, but some endocrine tests are fairly cheap, especially compared to stool or allergy tests, which aren’t anywhere near as reliable. Problems with the endocrine system can set you up for infections like candida overgrowth, so ruling them out is a good idea (where possible).
As for the ingredients, cellulose is vegetable fibre, which is fine, and rice flour is easily absorbed in the small intestine, but is probably in too negligible an amount to notice anyway. If you have bacterial overgrowth in the small intestine, it could potential cause issues.