CBD for Hashimoto's and the Thyroid: What Do Studies Say and Is It Safe

Let's start with the answer, as it is short, and few people state it directly. There is not a single clinical study that has examined cannabidiol in Hashimoto's disease. Neither randomized, nor open-label, nor even registered and ongoing. We checked this again on August 15, 2026, in the ClinicalTrials.gov registry and in the Europe PMC database, entering all variants of queries about cannabidiol, thyroid, thyroiditis, and hypothyroidism. The result: zero. This is not a trivial matter, as the entire narrative about CBD in this diagnosis is based on premises gathered from completely different diseases. The rest of the article explains what is actually known, why these premises are insufficient to consider cannabidiol as support in Hashimoto's, and where the real risks lie, which guides remain silent about. It concerns levothyroxine, liver enzymes, and iodine supplements.

KEY INFORMATION
• Zero clinical studies on CBD in Hashimoto and in any other thyroid disease (ClinicalTrials.gov, Europe PMC, August 2026).
• In 201 healthy adults, CBD did not change TSH, T3, or FT4, but in 5.6% it raised ALT or AST more than three times above normal (Florian et al., JAMA Internal Medicine, 2025).
• The dose of levothyroxine is determined by the doctor based on TSH. CBD is not a reason to change it.
• Selenium lowers anti-TPO antibodies, excess iodine may exacerbate thyroid autoimmunization.

Is there any clinical study on CBD in Hashimoto's disease?

No. There is not a single interventional study with cannabidiol for Hashimoto's disease, autoimmune thyroiditis, hypothyroidism, or Graves' disease in the ClinicalTrials.gov registry. Europe PMC does not return any clinical work on this topic. Status as of August 15, 2026.

The query "cannabidiol thyroid" returns three studies in the registry, none of which concern thyroid disease. Two describe pharmacokinetics in healthy volunteers, while the third examines the effect of CBD on liver enzymes. The thyroid appears only as one of the measured safety parameters, not as a treatment subject. We will describe this third study later in the text, as it provides the only human data on thyroid hormones with cannabidiol that we have.

This is not an oversight of a single database. The EFSA panel on nutrition in the updated position on the safety of cannabidiol (2026) searched the literature until June 2024 and confirmed that the data gaps from 2022 have not been closed. Among them, it explicitly mentions the endocrine system. This is a safety review, not an efficacy one, so it does not make any definitive conclusions on its own. However, it aligns with the research registry: there is nothing to summarize on the thyroid side.

We noticed a recurring pattern in texts that promise "regulation of the thyroid" through CBD. None of them cites a study involving individuals with Hashimoto because such a study does not exist. They reference works on other diseases, cell cultures, or rodents, and the conclusion is added at the end. Lack of evidence does not mean evidence of lack of effect, but it means that no one has a basis to promise anything.

What is Hashimoto and where did the interest in CBD come from?

Hashimoto is a chronic autoimmune thyroiditis in which the immune system produces anti-TPO and anti-TG antibodies against its own gland. Over time, this leads to the loss of active tissue and hypothyroidism. In areas with sufficient iodine supply, it is the most common cause of hypothyroidism.

It is necessary to distinguish between two concepts that are often conflated in guides. Hashimoto is a specific autoimmune disease. Hypothyroidism is a hormonal state that can have other causes as well: a past surgery, treatment with radioactive iodine, iodine deficiency, certain medications. A study conducted on drug-induced hypothyroidism does not provide any information about Hashimoto and vice versa.

The mere presence of antibodies is not yet a disease. A meta-analysis of 48 studies estimated the global prevalence of Hashimoto's at 7.5%, with a confidence interval of 5.7 to 9.6%, and in high-income countries at 8.4% (Hu i in., Frontiers in Public Health, 2022). The two largest projects in this comparison included over 22 million participants from 19 countries. According to this work, women are affected about four times more often. There is a lack of population data for Poland itself, so the percentages circulating in Polish guides have no source.

Interest in CBD arises from a list of symptoms rather than the disease mechanism. Fatigue, poor sleep, anxiety, low mood, and musculoskeletal pain persist in some patients even with normal TSH levels. These are precisely the areas where CBD has the most publications, although none of them pertain to the thyroid.

Do cannabinoid receptors in the thyroid prove that CBD works?

No. The presence of a receptor in tissue is an anatomical description, not proof of drug action. CB1 receptors have indeed been detected in the thyroid, but they have also been found in the liver and adipose tissue. The mere fact that something is present does not imply that influencing it will improve the course of an autoimmune disease.

The work referenced by such texts is Porcella i in., European Journal of Endocrinology, 2002. It demonstrated an active CB1 receptor in the thyroid of a rat. A study on rodents from over two decades ago, without CBD being used as a drug and without reference to autoimmunization.

There is one more detail that gets lost in guides. CBD has low affinity for CB1 and CB2 receptors and does not act on them like a classic agonist. The argument "cannabinoid receptors are in the thyroid, so cannabidiol will work on it" is therefore based on confusing CBD with other cannabinoids.

Do data from other autoimmune diseases transfer to Hashimoto?

Not to an extent that would allow for any promises. The review Pellati i in. (BioMed Research International, 2018) describes a decrease in the production of inflammatory cytokines after cannabidiol in human keratinocyte cultures, and attributes the inhibition of TNF-alpha and interleukin secretion in monocytes to the stimulation of the CB2 receptor. The anti-proliferative thread of this work concerns cancer cells, and its entire experimental layer consists of cell cultures and animals.

The reasoning "CBD modulates the immune system, so it should help with autoimmunization" has a serious gap. Modulation is not the same as suppressing a specific reaction against thyroid peroxidase. In an autoimmune disease, shifting the immune balance can work both ways, and no one has measured which direction it goes in Hashimoto. The EFSA panel noted in 2026 that no studies on the immunotoxicity of cannabidiol had been conducted at all, and for this reason recommended caution.

Separately, it is necessary to correct the frequently repeated abbreviation regarding multiple sclerosis. The registration data there pertains to nabiximols, a preparation combining THC with CBD, and the endpoint was spasticity, not the course of autoimmunization. This is not a study of CBD alone and says nothing about the destruction of the thyroid by lymphocytes.

A fair summary is this: the mechanism is interesting, the premises are consistent, and the translation to a patient with Hashimoto remains a hypothesis. A hypothesis is not a reason to change anything in treatment.

Does CBD affect the levels of TSH, FT3, and FT4?

In the only study that measured this in humans, there was no change. In a randomized double-blind study, 201 healthy adults took 5 mg of CBD per kilogram of body weight daily for 28 days. No difference was noted compared to placebo in TSH, total T3, or FT4 (Florian i in., JAMA Internal Medicine, 2025).

This is good news, but with three caveats. The participants were healthy, so they had neither autoimmunization nor levothyroxine in their bodies. The observation lasted four weeks, while Hashimoto is a disease that lasts for years. The dose was high, equating to over 300 mg daily for a person weighing 70 kg, so the conclusions pertain more to the upper range of exposure than a typical dose of oil.

Data from animals are less reassuring. EFSA noted in toxicological materials hormonal disturbances involving altered thyroid hormone levels. In a rat model of vitamin D3 deficiency, cannabidiol raised thyroxine by 59.9% and lowered TSH by 36.15% (Trivedi i in., Journal of Food Science and Technology, 2022). It must be honestly added that the authors interpreted this as an improvement in thyroid function and themselves proposed cannabidiol for hypothyroidism. For someone who already has a well-adjusted dose of levothyroxine, the same change means something different than for a rat with deficiency: it shifts the result on which the doctor bases treatment. In any case, we are talking about rodents, not humans.

The practical conclusion is simple. If you start CBD, inform your endocrinologist and maintain your current TSH monitoring schedule. Not to expect an improvement in results, but to notice any potential changes.

Can CBD be combined with levothyroxine?

No pharmacokinetic interaction between CBD and levothyroxine has been described. Levothyroxine is eliminated through deiodination and conjugation with glucuronic acid, not through CYP enzymes, which are inhibited by cannabidiol. The main mechanism of drug interaction of CBD here is therefore ruled out. Theoretical interaction remains with UGT enzymes, which cannabidiol inhibits, but no one has measured this in humans.

The most important thing in this article concerns the dosage of the medication. The dose of levothyroxine is determined by the doctor based on TSH, not on how one feels, an article on the internet, or a reaction to a supplement. Self-adjusting the dose is dangerous in both directions. A dose that is too low means a return of hypothyroid symptoms and a particular risk during pregnancy. A dose that is too high risks atrial fibrillation and loss of bone mass. No cannabis product is a reason to reduce or discontinue the dose. The only published signal in this pair actually goes in the opposite direction: in 22 children treated with cannabidiol for drug-resistant epilepsy, concurrent levothyroxine was associated with a CBD concentration 109.6% higher (Brstilo i in., Pharmaceutics, 2023). A small, non-randomized observation, which is a hypothesis to be tested.

There is still the issue of absorption, as levothyroxine is particularly sensitive in this regard. It is taken in the morning on an empty stomach, at least half an hour before eating, away from calcium and iron preparations, proton pump inhibitors, and coffee. CBD behaves exactly the opposite: after a fatty meal, its maximum concentration was 14 times, and the area under the curve 4 times higher than on an empty stomach, although the study included only eight adults with drug-resistant epilepsy (Birnbaum i in., Epilepsia, 2019). Both substances therefore disperse over time: the drug in the morning on an empty stomach, the oil with a meal later in the day. You can find more about absorption in the post about bioavailability of CBD.

How does CBD affect liver enzymes and the metabolism of other medications?

Cannabidiol inhibits cytochrome P450 enzymes. Measurements adjusted for binding to proteins and laboratory vessels showed inhibition of five enzymes: CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A. Three of them, namely CYP1A2, CYP2C19, CYP3A, cannabidiol additionally inactivated in a time-dependent manner (Bansal i in., Drug Metabolism and Disposition, 2020). The conjugating enzymes UGT stand apart. The effect is predictable: concentrations of other medications taken concurrently may increase. This applies to anyone with Hashimoto's who is taking something else besides the hormone.

This effect appears even with over-the-counter doses. The study was completed by twelve healthy volunteers, and a single 30 mg dose of CBD increased the area under the curve of amitriptyline by 13%, and the maximum concentration by 17% (Gorbenko i in., British Journal of Clinical Pharmacology, 2026). A review for doctors and pharmacists authored by Graham i in. (Expert Review of Clinical Pharmacology, 2022) collects the dosage ranges at which interactions become likely.

The second thread is the liver itself. In the referenced study involving 201 healthy adults, ALT or AST activity exceeded three times the upper limit of normal in 5.6% of those taking CBD and in none of the placebo group. Seven individuals met the criteria for withdrawal from the study due to suspected drug-induced liver injury, detected on days 21 and 28. These were healthy individuals, without chronic diseases and without medications.

Hence, a simple practical rule. If you are regularly taking more than one medication, a conversation with your doctor or pharmacist should precede the first drop, not follow it.

Do selenium and iodine support the thyroid in Hashimoto's?

Selenium has real data here, while iodine can work against you. This distinction is lost in guides that lump both elements together under the label "natural thyroid support." The difference is fundamental and worth knowing before purchasing anything.

A meta-analysis of 35 randomized studies showed that selenium supplementation lowers TSH in individuals not receiving hormonal treatment and reduces anti-TPO antibodies regardless of treatment. However, it did not change FT4, FT3, anti-TG antibodies, or thyroid volume, and adverse effects were comparable to the control group. The certainty of evidence was generally rated as moderate (Huwiler i in., Thyroid, 2024). Note what is not there: a decrease in antibody levels is a laboratory result, not proof that the patient feels better or requires hormonal treatment less frequently.

With iodine, the situation is the opposite. In a five-year observation of 3018 individuals from three Chinese regions with varying iodine supply, the five-year incidence of autoimmune thyroiditis increased from 0.2% with mild iodine deficiency to 1.0% with sufficient supply and 1.3% with excess (Teng i in., New England Journal of Medicine, 2006). Subclinical hypothyroidism behaved the same way. Therefore, with Hashimoto's, high-dose iodine preparations and dried seaweeds like kelp are a bad idea without medical supervision. Selenium also has an upper limit of intake, which can easily be exceeded when combining several preparations, as we discuss in the text about upper limits of supplements.

Frequently Asked Questions

Does CBD help with Hashimoto?

It is unknown because no one has checked it. There is not a single clinical trial of cannabidiol in Hashimoto's disease in the ClinicalTrials.gov registry or the Europe PMC database. Guides that discuss the effectiveness of CBD in this diagnosis rely on studies of other diseases or on cell cultures.

Does CBD affect TSH, T3, and T4 levels?

In the only study that measured this, it had no effect. In 201 healthy adults taking 5 mg of CBD per kilogram of body weight for 28 days, there was no difference compared to placebo in TSH, total T3, or FT4 (Florian et al., JAMA Internal Medicine, 2025). This data comes from healthy individuals, not from patients with Hashimoto.

Can CBD be taken together with levothyroxine?

No pharmacokinetic interaction has been described because levothyroxine is not primarily metabolized by CYP enzymes. However, inform your endocrinologist before starting. The medication is taken in the morning on an empty stomach, while CBD is absorbed much better with a fatty meal, so both substances naturally disperse over time.

What is the CBD dosage for Hashimoto's?

Such a dose does not exist. The dose is determined in studies on a specific diagnosis, and there are no studies on CBD in Hashimoto's, so any range of milligrams provided online for this disease is fabricated. EFSA calculated a temporary safe dose of 0.0275 mg per kilogram of body weight per day, which is about 2 mg for a person weighing 70 kg.

Can CBD be harmful in autoimmune disease?

This cannot be ruled out. The argument that CBD modulates immunity, thus helping in autoimmunity, works both ways: modulation is not the same as suppressing the response against the thyroid. EFSA noted in 2026 that no immunotoxicity studies of cannabidiol had been conducted at all, and recommended caution.

Do selenium and iodine help with Hashimoto?

Selenium lowers anti-TPO antibodies and TSH in individuals without hormonal treatment, with moderate certainty of evidence (Huwiler et al., Thyroid, 2024). Iodine works the opposite way: in a five-year observation of 3018 individuals, higher iodine intake was associated with more frequent autoimmune thyroiditis (Teng et al., NEJM, 2006).

If after talking to your doctor you want to try CBD as symptomatic support, we have gathered products from this category. hemp oils.

This article is for informational and educational purposes only and does not constitute medical advice. Before starting to use hemp or CBD for therapeutic purposes, consult your doctor, especially if you are taking other medications, are pregnant, or breastfeeding.

Author: Michał Waluk · Opublikowano: 2026-06-02 · Aktualizacja: 2026-08-15