What to Look for in a Thyroid Supplement in Australia

The best thyroid supplement in Australia is the one you actually need, with a label you can read in full, nothing in it that works against your thyroid or your medication, and clear instructions for taking it around your tablet. There is no single product that is right for everyone, but there is a short checklist that sorts the sensible options from the risky ones.

This guide is for Australians with Hashimoto's, an underactive thyroid, or no thyroid after surgery. If you want the list of ingredients to steer clear of, our guide to supplements to avoid with an underactive thyroid covers that. This one is about how to choose.

1. Start with whether you need one

Before any product, start with a test. The Australian Thyroid Foundation's position is that it does not recommend vitamins, supplements or herbal extracts unless a test has shown a definite deficiency that food alone has not fixed. That is a sensible place to begin. Iron, vitamin B12 and vitamin D are worth asking your GP about, because shortfalls in each are linked with an underactive thyroid and they can all leave you tired. Our guide to still being tired with Hashimoto's and a normal TSH explains what to ask for.

2. Know what kind of product it is

In Australia, something you swallow for your health is regulated either as a medicine or as a food, and the label tells you which.

• AUST R on the pack means a registered medicine. These are evaluated by the Therapeutic Goods Administration (TGA) for safety, quality and efficacy before they go on sale.
• AUST L means a listed medicine, which is where most vitamins and herbal supplements sit. The TGA requires them to be made to good manufacturing standards and to use permitted ingredients, but in its own words they "have not been assessed for efficacy" before sale. The sponsor certifies that the product meets the rules and it is included on the register.
• No AUST number usually means a food, such as a powder or drink. Foods are covered by the Food Standards Code, which Food Standards Australia New Zealand (FSANZ) sets and the states and territories enforce. A food's health claims must not refer to preventing, curing or alleviating a disease.

None of these is automatically better than another. What matters is that you know what you are buying, and that a "thyroid" product is not making promises its category does not allow.

3. A full label, with amounts

A trustworthy product lists its ingredients and shows how much of the key nutrients is in a serve. Be cautious when most of a formula sits inside a "proprietary blend" with one total weight: you cannot tell how much of the active ingredients you are getting, or check them against your other supplements. You want to be able to hand the label to your pharmacist and have them see exactly what is in it.

4. No added iodine or kelp

Iodine is the ingredient most often added to thyroid supplements, frequently as kelp or seaweed. For many people with an underactive thyroid it does more harm than good. In a five-year study of more than 3,000 people in China, those living with more than adequate or excessive iodine intake developed autoimmune thyroiditis and a mildly underactive thyroid more often over those five years than those with mildly low intake. Australia's own nutrient reference values set an upper limit of 1,100 micrograms a day for adults, and note that people with thyroid disorders may react badly even below that.

Seaweed adds a second problem: the amount varies enormously. One analysis of edible seaweeds found up to 8,165 micrograms of iodine per gram of kelp granules. If a thyroid product lists iodine, kelp, seaweed or bladderwrack, it is worth asking your doctor before you take it. More on why in our guide to iodine and why more isn't better.

5. No thyroid extract or "glandulars"

Some products sold as thyroid support contain dried animal thyroid tissue, listed as thyroid, bovine thyroid or glandular. Tissue can carry real thyroid hormone. When US researchers tested ten thyroid support supplements, nine contained T3 and five contained T4, some at amounts in the range of a prescribed dose. A later analysis by US Food and Drug Administration scientists found measurable hormone in 11 of 19 glandular products. For anyone on levothyroxine, that is an unmeasured extra dose. These were US products, but many are sold to Australians online.

6. Clear instructions for your medication

A good thyroid product should tell you how to take it around levothyroxine, because timing matters as much as ingredients. The Australian product information for levothyroxine says to take it on an empty stomach, at least 30 minutes and preferably 60 minutes before food, and that calcium, magnesium and iron supplements should be separated from it by several hours. The Australian Thyroid Foundation passes on a recommendation of at least four hours between your tablet and other medications. If a product with minerals in it does not mention your thyroid tablet at all, that is a gap.

Our guide to supplements and levothyroxine timing walks through a day.

7. Honest claims

Read the claims as carefully as the ingredients. Be wary of any product that promises to fix, reverse or cure your thyroid, to boost your metabolism, or to reduce or replace your medication. After thyroid surgery or radioactive iodine, your body cannot make enough thyroid hormone on its own, and no supplement changes that. A trustworthy product says plainly that it sits alongside your medication, not instead of it.

8. Check biotin and herbs with your pharmacist

Two more things to look for on the label. Biotin, common in hair and B-complex products, can make thyroid test results read wrongly; in one study, 9 of 23 biotin-based tests gave false results while people were taking it. Herbs such as ashwagandha (withania) may shift thyroid hormone levels, and the TGA has issued safety advice about a rare risk of liver injury from it. Neither is a reason to panic. Both are reasons to tell your doctor and pharmacist what you take.

A quick buyer's checklist

Ask	Good sign
Do I need it?	A test has shown a gap, or your GP agrees it is worth trying.
What kind of product is it?	You can see AUST R, AUST L, or that it is a food, and the claims fit that category.
Can I see what is in it?	A full ingredient list and the amounts of the key nutrients.
Iodine, kelp or seaweed?	None added.
Thyroid extract or glandular?	None.
Biotin or hormone-shifting herbs?	None, or you have checked with your doctor.
Instructions around my thyroid tablet?	Clear timing, especially if it contains minerals.
What does it promise?	Support alongside your medication. Never a cure or a replacement.

Where ThyroBase fits

We make one, so here is how it sits against this list, plainly. ThyroBase is a food, not a listed medicine: two daily drink powders, one for the morning and one for the evening, made in Australia to the Food Standards Code. The full ingredient list and nutrition panel are on every pouch. There is no added iodine, no kelp, no thyroid extract, no added biotin, no ashwagandha and no added caffeine.

It contains minerals, so the timing is part of the instructions: if you take your thyroid tablet in the morning, the AM serve goes at least four hours after it. It is designed to sit alongside your thyroid medication, never instead of it, and it is Australia's first thyroid-specific AM & PM nutrition system. It is not for everyone, and we say so: here is who it is, and is not, designed for.

The best question to ask about any supplement is "what is this for?"

If the honest answer is "I'm not sure", start with a test, not a purchase.

Frequently asked questions

What is the best supplement for thyroid health in Australia?

There is no single best product for everyone. The right choice depends on what a test shows you need. A sensible thyroid product shows what is in it, has no added iodine, kelp or thyroid extract, gives clear timing around levothyroxine, and says it sits alongside your medication rather than replacing it.

Is there a thyroid supplement without iodine in Australia?

Yes. Many products marketed for thyroid support contain iodine or kelp, but not all do. Check the ingredient list for iodine, potassium iodide, kelp, seaweed or bladderwrack. ThyroBase, for example, has no added iodine and no kelp.

What does AUST L mean on a supplement?

AUST L means the product is a listed medicine on the Australian Register of Therapeutic Goods. It must be made to good manufacturing standards with permitted ingredients, but the TGA has not assessed it for efficacy before sale. AUST R products are registered medicines that the TGA does evaluate for efficacy.

Should I take a supplement if my thyroid tests are normal?

Not automatically. The Australian Thyroid Foundation recommends against taking vitamins or supplements unless a test shows a definite deficiency that food has not fixed. If you still feel unwell with normal results, ask your GP about checking iron, B12 and vitamin D first.

The honest takeaway

Choosing a thyroid supplement in Australia comes down to a few questions. Do you need it? What kind of product is it? Can you see everything in it? Is there anything that works against your thyroid or your tablet? And does it promise only what it can honestly deliver? Take your shortlist to your pharmacist. They can check it against everything else you take in five minutes.

ThyroBase is a nutritional supplement and is not intended to diagnose, treat, cure, or prevent any disease. It is designed to sit alongside your thyroid medication, not replace it. This article is general information, not medical advice. Never start, stop or change a supplement or prescription medication without speaking to your doctor or pharmacist first.

References

Australian Thyroid Foundation. Hypothyroidism / Underactive Thyroid. thyroidfoundation.org.au.
Therapeutic Goods Administration. How we regulate medicines. tga.gov.au. 2025.
Therapeutic Goods Administration. Understanding listed and registered complementary medicine regulation. tga.gov.au. 2025.
Therapeutic Goods Administration. Know how food and medicine are regulated. tga.gov.au.
Food Standards Australia New Zealand. Nutrition, health and related claims (Standard 1.2.7). foodstandards.gov.au. 2025.
Teng W, Shan Z, Teng X, et al. Effect of iodine intake on thyroid diseases in China. New England Journal of Medicine. 2006;354(26):2783-93.
National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand: Iodine. eatforhealth.gov.au.
Teas J, Pino S, Critchley A, Braverman LE. Variability of iodine content in common commercially available edible seaweeds. Thyroid. 2004;14(10):836-41.
Kang GY, Parks JR, Fileta B, et al. Thyroxine and triiodothyronine content in commercially available thyroid health supplements. Thyroid. 2013;23(10):1233-7.
Pawar RS, Sagi S, Leontyev D. Determination of thyroid hormones in dietary supplements using liquid chromatography-tandem mass spectrometry. Drug Testing and Analysis. 2022;14(3):578-86.
Australian Product Information: Levothox (levothyroxine sodium) tablets. medsinfo.com.au.
Li D, Radulescu A, Shrestha RT, et al. Association of biotin ingestion with performance of hormone and nonhormone assays in healthy adults. JAMA. 2017;318(12):1150-60.
Therapeutic Goods Administration. Medicines containing Withania somnifera (Withania, Ashwagandha). Safety alert. tga.gov.au. 2024.