How Ashwagandha Improves Your Thyroid Health
By Dr. Kevin Passero
If you’ve been told your thyroid is “a little sluggish,” you’re not alone. Millions of people live with hypothyroidism or the milder subclinical hypothyroidism, which can leave you feeling tired, cold, foggy and frustrated.
While prescription thyroid hormone is the standard for treatment recommended by many traditional doctors, more people are exploring natural ways to support thyroid health—one of which is ashwagandha.
But can this ancient herb, used traditionally in Ayurvedic medicine, really help bring your thyroid back into balance? Let’s look at what the research says.
Ashwagandha: The Stress-Balancing Root
Ashwagandha (Withania somnifera) is a small shrub in the nightshade family. For thousands of years, it’s been used as an adaptogen—a plant that helps the body adapt to stress.
And now modern science is catching up with studies showing that ashwagandha’s active compounds, called withanolides, can support multiple systems in the body. One area of growing interest is its impact on the hypothalamus–pituitary–thyroid (HPT) axis, the communication line between your brain and your thyroid gland.
How Ashwagandha Can Support Thyroid Function
When stress hormones like cortisol are elevated for too long, thyroid hormone production can slow down. Ashwagandha has been scientifically proven to help in two ways:
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Reducing stress load: By calming the stress response and lowering cortisol levels, ashwagandha may lift some of the suppression on thyroid hormone production.
- Directly stimulating hormone release from the thyroid: Animal and human studies show increases in both T3 and T4 hormones after supplementation.
The Study That Everyone’s Talking About
A randomized, double-blind, placebo-controlled trial tested people with subclinical hypothyroidism who took 600 mg of standardized ashwagandha root extract daily.
The results?
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TSH levels dropped (a sign the thyroid was working more efficiently).
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Thyroid hormones T3 and T4 levels rose into normal range.
- Side effects were minimal and temporary.
This is the strongest human evidence so far linking ashwagandha to improved thyroid function.
How to Use Ashwagandha for Low Thyroid Function
If you decide that ashwagandha is a good option for you, here are some general guidelines based on clinical research:
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Dose: 600 mg of standardized root extract daily (often split into two doses).
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Timing: Usually taken with food to avoid stomach upset.
- Duration: Results begin at 8 weeks, but it's best to assess progress after 90 days.
- Monitoring: Have your TSH, T3 and T4 checked before starting and after 2–3 months.
Safety and Cautions
Ashwagandha is extremely well-tolerated, but it's not for everyone. You should seek medical guidance if you:
- Have hyperthyroidism (it may push your thyroid too high).
- Are pregnant or breastfeeding.
- Have hormone-sensitive cancers.
- Take medication for blood pressure, blood sugar or sedation (possible interactions).
- Have an autoimmune condition.
Rare cases of high doses have been linked to thyrotoxicosis (too much thyroid hormone) or liver injury—so inform your healthcare provider that you are taking an ashwagandha supplement. Selecting an ashwagandha supplement with excellent safety data from human clinical trials will reduce the risk of adverse effects.
Ashwagandha is safe to take along with thyroid medication and works by addressing the underlying mechanisms conventional approaches may miss—helping your thyroid perform better, improving thyroid hormone conversion, supporting metabolism and restoring energy and mental clarity.
It is important to note that if you are taking ashwagandha along with medication, you should have your thyroid levels monitored for any needed change in medication dosage.
Bottom Line
Ashwagandha is one of the few herbs with human clinical data showing measurable improvements in thyroid hormone levels—especially in mild or subclinical cases.
Taking ashwagandha daily is a safe and effective natural way to support healthy thyroid function, restore energy and rebalance metabolism—based on both clinical research and the results I’ve seen in my own patients.
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