The Potential Thyroid Side Effects of Quercetin Supplementation

Quercetin is a plant-based flavonoid that has been used in traditional medicine for centuries and is now being studied as a dietary supplement. While it can have many positive benefits, there are potential side effects associated with quercetin supplementation, particularly when it comes to the thyroid. In particular, some studies suggest that high doses of quercetin may lead to an increase in T3 and T4 hormone levels which could potentially cause hyperthyroidism or other thyroid issues. Additionally, quercetin has been linked to decreased iodine absorption which could also affect the functioning of the thyroid gland. Therefore, those taking supplements should be aware of these risks before starting any regimen and consult their doctor if they experience any symptoms related to their thyroid health.

Introduction to Quercetin

Quercetin is a type of flavonoid found in many fruits and vegetables, as well as some herbs and spices. It has been studied for its potential anti-inflammatory and antioxidant properties, making it a popular supplement choice for those looking to improve their health. However, quercetin supplementation may have side effects on the thyroid gland due to its ability to interfere with certain hormones involved in metabolism regulation. Therefore, it is important to be aware of the potential thyroid side effects before taking quercetin supplements.

Overview of Thyroid Function

The thyroid is a gland located in the neck that secretes hormones which regulate metabolic processes, such as growth and development, body temperature, and heart rate. It also helps to convert food into energy for use by the body’s cells. When something affects the production of these hormones or their ability to be used by the body it can lead to potential health issues related to metabolism and other bodily functions. Quercetin supplementation has been linked with potential side effects on thyroid function due its antioxidant properties which can inhibit certain enzymes involved in hormone synthesis.

In some cases quercetin supplementation may cause hyperthyroidism, where too much thyroxine (T4) is produced leading to an increased metabolism and potentially symptoms like weight loss, fatigue, anxiety or insomnia if left untreated. On the other hand hypothyroidism can occur when too little T4 is produced resulting in slowed down metabolism and symptoms like weight gain, constipation or depression if not addressed properly. Therefore it’s important for people taking quercetin supplements to monitor their thyroid levels closely so they are able detect any changes early on before serious problems arise from imbalanced hormone levels caused by quercetin consumption

Potential Side Effects of Quercetin on the Thyroid

Quercetin is a flavonoid found in many plants and foods, including onions, apples, berries and green tea. It has been studied for its potential health benefits due to its antioxidant activity. While quercetin supplementation may provide some health benefits, it can also have adverse effects on the thyroid gland if taken in high doses or over an extended period of time.

High doses of quercetin can interfere with the body’s ability to absorb iodine which is essential for the production of hormones by the thyroid gland. This can lead to hypothyroidism (underactive thyroid) as well as hyperthyroidism (overactive thyroid). Additionally, long-term use of quercetin supplements could increase levels of thyroxine which could result in symptoms such as anxiety and rapid heartbeat.

Other side effects related to taking too much quercetin include nausea, headaches and dizziness which are all signs that your body isn’t tolerating it well or that you’re taking too much at one time without giving your body enough time to adjust accordingly. Therefore, before starting any supplement regimen it’s important to consult with a medical professional who will be able to advise on safe dosage amounts based on individual needs and conditions..

Possible Benefits of Quercetin for the Thyroid

Quercetin is a flavonoid found in many fruits and vegetables that has been studied for its potential health benefits, including its effects on the thyroid. Studies have shown that quercetin supplementation may help to improve thyroid function by increasing levels of certain hormones such as triiodothyronine (T3) and thyroxine (T4). It may also reduce inflammation associated with autoimmune diseases like Hashimoto’s disease, which can cause hypothyroidism. Additionally, quercetin has antioxidant properties which may protect against oxidative damage caused by free radicals, which can contribute to thyroid dysfunction.

Quercetin has also been linked to improved energy levels due to its ability to support healthy metabolism and promote efficient utilization of nutrients from food sources. In addition, it can increase blood flow throughout the body, allowing more oxygen and nutrients to reach cells while reducing fatigue associated with hypothyroidism or other conditions affecting the thyroid gland. Lastly, supplementing with quercetin may help lower cholesterol levels since it prevents LDL oxidation in the bloodstream—a process linked to an increased risk of heart disease among people with hypothyroidism or other forms of impaired thyroid function.

Although there are some possible benefits associated with taking quercetin supplements for those suffering from various types of thyroid disorders or dysfunction, there is still not enough evidence available at this time regarding any potential side effects related specifically to taking these supplements long-term; however one should always consult their doctor before starting any new treatment regimen involving dietary changes or supplementation in order to ensure safety and efficacy when treating any condition related to the thyroid gland

Interactions with Other Drugs and Supplements

Quercetin supplementation may interact with other drugs and supplements, potentially leading to side effects related to the thyroid. For instance, taking quercetin in combination with blood thinners such as warfarin can increase the risk of bleeding due to its antiplatelet properties. Additionally, it is important for people on thyroid medications to be aware that quercetin may reduce their absorption and effectiveness. Therefore, those taking prescription medication should consult a doctor before supplementing with quercetin or any other supplement known to interact with their medication.

Quercetin also interacts with certain dietary supplements that are used for treating hypothyroidism such as iodine and selenium, which could lead to an increased risk of developing hyperthyroidism if taken together in high doses over a long period of time. Furthermore, caution should be exercised when combining quercetin supplementation with herbal remedies such as ashwagandha since this herb has been shown to influence thyroid hormone levels too. Ultimately, it is best for individuals looking into supplementing their diet with quercetin first discuss potential interactions and side effects associated with their current regimen before making any changes or additions


Quercetin is a natural flavonoid found in many plants and foods that has been studied for its potential health benefits, including as an antioxidant, anti-inflammatory, and immune system booster. However, it may also have some side effects on the thyroid if taken in high doses or over prolonged periods of time.

Studies suggest that quercetin can interfere with iodine uptake into the thyroid gland and reduce levels of thyroxine (T4) hormone production in the body. This could lead to hypothyroidism symptoms such as fatigue, weight gain, dry skin, constipation and depression if left untreated. It is important to speak with a doctor before taking any supplement containing quercetin to ensure that it does not interact negatively with other medications or supplements you are taking.