Feeling tired even after a full night’s sleep or cold when everyone else is comfy can leave you wondering what’s going on inside your body. Add dry skin and foggy thinking, and it’s all too common to feel like you’ve lost your spark. Your thyroid could be part of the story. Did you know? Women are about 10 times more likely than men to get Hashimoto’s thyroiditis, a leading cause of hypothyroidism [1,2]. No wonder so many people look for supplements for hypothyroidism once they get a diagnosis. Selenium, vitamin D, iodine: the shelves are full of bottles with big promises. Here’s a look at the best supplements worth discussing with your doctor for hypothyroidism, what each one does, and what to check first.
Before we dive in, one thing to keep in mind: no supplement replaces your thyroid medicine. Think of these as helpful additions, not a cure.
Also read: World Thyroid Day: Tips To Manage Hypothyroidism
What is Hypothyroidism, and How Does it Happen?
Hypothyroidism means your thyroid doesn’t make enough thyroid hormone. Your body uses this hormone to burn energy, stay warm, and keep your brain, heart, and muscles working well. When levels drop, your body slows down. You may feel cold or tired, have dry skin or constipation, feel low, or forget things easily [3].
Here’s how the pieces connect. Your pituitary gland, a tiny gland in your brain, sends out a signal called TSH. TSH tells your thyroid to make hormones (T4 and T3). If the thyroid can’t keep up, the pituitary pushes harder, and TSH rises [3].
What makes a thyroid underactive? A common reason is autoimmune disease like Hashimoto’s, where your body attacks your own thyroid by mistake. Other causes include thyroid surgery, radiation treatment, certain medicines like lithium, too little iodine, and pituitary gland damage [2,3].
Quick Byte:
| Many people think a high TSH means hyperthyroidism. It’s the opposite. A high TSH usually means your thyroid is underactive, so your brain keeps pushing it to work harder [1]. |
5 Best Supplements for Hypothyroidism Worth Knowing About
First, a reality check. Supplements can help correct a confirmed deficiency, but they don’t replace thyroid hormone treatment. Evidence that supplements improve thyroid function or symptoms in people without a deficiency is still limited [1,2].
1. Selenium
Your thyroid needs selenium to make hormones, and selenium also helps calm inflammation [1]. A review of 35 studies found that selenium slightly lowered thyroid antibodies in people with Hashimoto’s and reduced TSH levels in those not taking thyroid hormone medication [1]. But lower antibody levels don’t necessarily mean less thyroid inflammation, better symptoms, or slower disease progression. So this is an early signal, and the data is still limited. Researchers say we need more studies before we know if selenium can slow the progression to hypothyroidism [1]. So it’s a promising helper, not a guaranteed fix. Ask your doctor about the right amount before you start.
*Thyroid antibodies are proteins made by the immune system that can mistakenly target the thyroid gland.
2. Vitamin D
Vitamin D does more than keep your bones strong. People with Hashimoto’s often run low on it. A 2022 review notes that several studies have shown benefits from vitamin D and selenium supplements [2]. In one study, people with Hashimoto’s and low vitamin D saw their thyroid antibody levels fall by about 20.3% after taking vitamin D supplements [2]. But a drop in antibodies doesn’t prove you’ll feel better, and it’s not clear whether these changes improve symptoms or thyroid function. A simple blood test shows whether you need vitamin D, so you don’t have to guess.
3. Iodine
Your thyroid builds its hormones out of iodine. Too little can cause hypothyroidism and goiter, a swollen thyroid [4]. Iodine deficiency remains a concern worldwide, with around 683 million people living in 25 countries where iodine intake is insufficient [4]. Most adults (non-pregnant) need about 150 mcg of iodine a day from all sources combined, like iodized salt, fish, eggs, and dairy. That’s your total daily intake, not a supplement dose [4]. But too much iodine can cause the same thyroid problems, especially in people with autoimmune thyroid disease [4]. So skip high-dose kelp (kelp is a large seaweed that’s very high in iodine) pills unless your doctor says yes.
4. Iron
Nutrient gaps, including low iron, can occur alongside Hashimoto’s, so your doctor may check your iron levels [2]. If your report shows low iron, your doctor may suggest a supplement. But iron can also interfere with your thyroid pill [3]. Keep iron supplements at least 4 hours apart from your thyroid pill [5]. Ask your doctor to help you set a daily schedule that works for you.
5. Vitamin B12
People with Hashimoto’s often have other nutrient gaps too, and B12 is one of them [2]. Experts still debate how much B12 helps the thyroid itself [2]. Tiredness is a common sign of hypothyroidism [3], and many things can cause it, so it’s worth testing your B12 before you buy anything. If it’s low, your doctor can guide the form and amount.
Supplements aren’t the only thing that matters when managing hypothyroidism. How you take your thyroid medication matters too.
Read this: Hypothyroidism: Are You Making These Common Mistakes With Your Medication?
Before You Try Any Supplements for Hypothyroidism
“Natural” doesn’t mean risk-free. Some supplements and medicines can change how well your thyroid pill works. but not all in the same way. Calcium, iron, and antacids can block your body from absorbing the thyroid pill, so keep them at least 4 hours apart [5]. Some supplements, such as biotin (vitamin B7), can also affect thyroid care. Although it doesn’t change how the pill works, it can interfere with thyroid blood tests and give wrong results, so stop biotin supplements at least 2 days before a test. Tell your doctor if you take any other medicine or supplement before testing.
Your doctor will usually recheck your blood 6 to 8 weeks after any change in your thyroid dose [3]. Also, watch out for any product that promises to “cure” hypothyroidism, because these claims may be misleading.
FAQs
What are the first signs of hypothyroidism?
Your body slows down, so you may feel cold or tired, have dry skin, or get constipated. Some people also feel low or forget things easily. Not everyone has all of these, and other health problems can cause them too, so a blood test is the only way to know for sure [1].
Which blood tests diagnose hypothyroidism?
Doctors mainly use two tests: TSH and free T4. TSH goes up when your thyroid isn’t making enough hormone, and free T4 shows how much usable hormone is in your blood. A T3 test is rarely needed [1].
Can low iodine cause hypothyroidism?
Yes. Your thyroid needs iodine to make hormones, so too little can lead to hypothyroidism [1]. Other causes include Hashimoto’s, thyroid surgery, radiation, and some medicines like lithium [1].
Do calcium or iron supplements affect thyroid medicine?
Yes. Calcium, iron, and antacids can reduce how much thyroid medicine your body absorbs, so keep them at least 4 hours apart [5]. Biotin doesn’t change absorption, but it can throw off thyroid blood test results, so stop it at least 2 days before a test [5]. Tell your doctor if you start or stop any of them [3].
How do I know if my thyroid medicine dose is wrong?
Too little medicine can leave you tired, cold, or constipated. Too much can make you feel nervous, hot, or shaky, with a fast heartbeat or weight loss. Tell your doctor if you notice these signs [1].
How often should I get my thyroid tested?
Doctors usually check your blood 6 to 8 weeks after you start or change your dose. You may need checks more often if you’re pregnant or take other medicines [1].
Do I need thyroid medicine for life?
Most people do, and the dose may change over time. If your thyroid problem came from a virus or started after pregnancy, it may go away [1]. Never stop your medicine without your doctor’s help [1].
Should I take thyroid supplements during pregnancy?
Tell your doctor if you’re planning on getting pregnant or already pregnant. You may need more frequent thyroid checks [1], and your iodine needs go up during pregnancy [3]. Don’t start any new supplement on your own.
Disclaimer: This article is for general information only and isn’t a substitute for professional medical advice. Please talk to a doctor before starting any new supplement, especially if you take thyroid medicine. Never stop or change your thyroid medicine on your own.
References:
1. Miragaya J. Does Selenium Supplementation Prevent Hypothyroidism in Hashimoto’s Thyroiditis? [Summary of Huwiler VV, et al. Thyroid. 2024 Feb 16; PMID: 38243784]. Clinical Thyroidology for the Public. American Thyroid Association. 2024 Jul;17(7):5-6 [cited 2026 Oct 12]. Available from: https://www.thyroid.org/patient-thyroid-information/ct-for-patients/july-2024/vol-17-issue-7-p-5-6/
2. Mikulska AA, Karaźniewicz-Łada M, Filipowicz D, Ruchała M, Główka FK. Metabolic Characteristics of Hashimoto’s Thyroiditis Patients and the Role of Microelements and Diet in the Disease Management: An Overview. Int J Mol Sci. 2022 Jun 13;23(12):6580. doi:10.3390/ijms23126580. PMID: 35743024. PMCID: PMC9223845 [cited 2026 Oct 12]. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC9223845/
3. Adult Hypothyroidism. American Thyroid Association. 2025 [cited 2026 Oct 12]. Available from: https://www.thyroid.org/wp-content/uploads/patients/brochures/Hypo_brochure.pdf
4. Iodine: Fact Sheet for Health Professionals. Office of Dietary Supplements, National Institutes of Health. Updated 2024 Nov 5 [cited 2026 Oct 12]. Available from: https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
5. LEVO-T (levothyroxine sodium) tablets: Prescribing Information. U.S. Food and Drug Administration. Revised 2026 May [cited 2026 Oct 12]. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/021342s028lbl.pdf
(The article is written by Nancy Dixit, Associate Manager, Clinical Health & Content, Medical Affairs, and reviewed by Monalisa Deka, Deputy Manager, Clinical Health & Content, Medical Affairs.)
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