Hashimoto's Thyroiditis Flare-Up: Common Symptoms And Causes

Hashimoto’s thyroiditis (or Hashimoto’s disease) causes the body’s immune system to attack the thyroid gland. Eventually, the thyroid gland fails to produce enough hormones to regulate the metabolism, which can cause serious health complications.

Many people with Hashimoto’s disease may eventually develop hypothyroidism. Hypothyroidism, or underactive thyroid, affects 5%¹ of Americans, making it the most prevalent thyroid condition in the country.

Hashimoto’s thyroiditis can be successfully treated, but some factors, including stress and medication, can cause your symptoms to flare up. Find out what causes a Hashimoto’s thyroiditis flare-up and the symptoms to watch out for.

Have you considered clinical trials for Hashimoto's disease?

We make it easy for you to participate in a clinical trial for Hashimoto's disease, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What is Hashimoto’s disease?

The thyroid gland at the front of your neck produces hormones (T3 and T4) that control how fast you burn energy. This hormone production is controlled by the pituitary gland which produces a hormone called thyroid-stimulating hormone (TSH).

In Hashimoto’s disease, the immune system mistakenly attacks and damages the thyroid gland. Over time, this can develop into hypothyroidism, where the thyroid stops producing the hormones your body needs. The condition can cause several symptoms including fatigue and unexplained weight gain, but these symptoms can be eased using hormone therapy to increase thyroid hormone production.

Symptoms of a Hashimoto’s thyroiditis flare-up

Some of the earlier signs and symptoms of Hashimoto’s disease are non-specific and could be mistaken for other diseases, so your doctor will closely examine your medical history and carry out a thorough examination to make a diagnosis. Most symptoms take months or even years to develop and vary from patient to patient.

You may be suffering from a Hashimoto's disease flare-up if you have any of these common symptoms:


A noticeably enlarged thyroid called a goiter is one of the most common symptoms of Hashimoto’s disease. It makes the neck look swollen and can make it harder for you to swallow food.

Unexplained weight gain

Thyroid hormones regulate your metabolism (the rate at which you burn energy). When your thyroid underproduces hormones, it slows down the metabolic process which can sometimes cause unexpected weight gain.


Lower hormone levels cause many of your body’s processes to slow down which can cause fatigue.

Skin changes

You might notice that your skin becomes pale or puffy — this is caused by increased deposits of mucopolysaccharides (including hyaluronic acid)² which attract water and cause swelling.

Muscle aches and joint pain

Muscle aches and joint pain³, especially around the shoulders and hips, may suggest you are having a Hashimoto’s disease flare-up. This occurs when your metabolism slows and fluids build up faster in your joints.


Constipation is among the most common symptoms of a Hashimoto’s thyroiditis flare-up. When your thyroid gland isn’t producing enough hormones to meet your body’s needs, your digestive processes may slow down, leading to fewer bowel movements.

Cold intolerance

The thyroid gland also regulates your body temperature. Your body’s metabolism slows as your thyroid gland produces less hormone, causing a drop in body temperature and narrowing of blood vessels in the skin which increases your sensitivity to cold.

Fertility problems

Your menstrual cycle and ovulation may be disrupted⁴ when your thyroid isn’t producing enough hormone. This can cause fertility problems.

Hair loss

A 2015 study⁵ found that T3 and T4 hormones affect hair growth, and when production of these hormones decreases, hair growth also slows. This can cause increased hair fall and hair thinning across the scalp. The same study also found that Hashimoto’s thyroiditis may reduce the body’s ability to heal wounds.


Early studies⁶ have found that people with clinical depression have more antithyroid antibodies, although the relationship between depression and Hashimoto’s disease is still unclear.

Risk factors

The following factors could increase your risk of a Hashimoto’s thyroiditis flare-up:


Stress may not directly cause a Hashimoto’s thyroiditis flare-up, but it’s thought to worsen the condition. A recent study⁷ found that antithyroglobulin antibody levels were significantly reduced in 25 to 76-year old female people who underwent an eight-week stress management program.


Drugs⁸ that suppress the pituitary gland’s production of TSH hormone can cause hypothyroidism in people with a high risk of Hashimoto’s thyroiditis. Iodine-based medications can also lower T3 and T4 hormone levels, which can cause hypothyroidism.

Nutritional factors

Iodine deficiency can cause goiter and hypothyroidism as iodine is a mineral that helps produce and regulate thyroid hormones.


Hashimoto’s disease is thought to run in families, so you may be more at risk if someone in your family has the condition. To diagnose Hashimoto’s thyroiditis, your doctor will ask for information about your family’s medical history.


Up to 50%⁹ of people treated with radiation therapy for head and neck cancers may develop hypothyroidism since the thyroid is sensitive to radiation.

Radiation therapy can lower your TSH levels and increase thyroid antibodies in your blood¹⁰ which can elevate your risk of developing Hashimoto’s thyroiditis and hypothyroidism.

Radiation-induced hypothyroidism is known to develop months or even years after radiation therapy.

Who might be affected by Hashimoto’s thyroiditis?

Hashimoto’s thyroiditis affects around 2%¹¹ of Americans, while women have a higher risk of developing Hashimoto’s and hypothyroidism than men. 

Some reasons for this include women’s increased immune reactivity¹² and because more genes involved in immunity originate from X chromosomes (women have two X chromosomes while men only have one), increasing the risk of gene mutation¹³ and the development of autoimmune diseases.

The risk rises in middle-aged and older women¹⁴, and people with autoimmune diseases like lupus, rheumatoid arthritis, type 1 diabetes, and celiac disease also have increased risk.

Medical complications

Diagnosing Hashimoto’s thyroiditis early can help you get the medical treatment you need to reduce your risk of developing serious medical complications.

Many people see improvements when taking thyroid hormone replacement therapy and making changes to their diet; however, a Hashimoto’s disease flare-up could go undetected. Untreated, the condition could lead to severe complications, including:

Myxedema coma

Myxedema coma is a severe and life-threatening hypothyroidism complication that can be triggered by a range of events, most commonly certain medications, infections, or exposure to low temperatures.

The condition is characterized by a deteriorated mental state (confusion, fatigue, apathy) and hypothermia, but rarely causes the patient to fall into a coma despite the name.

Risks to fertility and pregnancy

Hashimoto’s disease can cause the menstrual cycle to become irregular, which can cause fertility problems. During pregnancy, Hashimoto’s disease increases the risk of preeclampsia, heart failure, placental abruption, anemia, low birth weight, preterm birth, and miscarriage¹⁴.


A Hashimoto’s disease flare-up may cause the pituitary gland to produce more TSH to rebalance hormone levels. Continued overproduction of TSH causes the thyroid to become enlarged, leading to a painless but uncomfortable condition called goiter. People with goiter have a large swelling at the front of the neck and may have difficulty swallowing or breathing.

Heart complications

When Hashimoto’s disease disturbs the metabolic balance, it can cause cholesterol levels to build up. High cholesterol is one of the risk factors associated with heart failure and cardiovascular diseases.

When to see a doctor

Hashimoto’s thyroiditis should be diagnosed and treated by a medical professional. If you have a flare-up while undergoing treatment, speak to your doctor immediately so they can review your dosage and check for other conditions that could be interfering with your treatment.

Diagnosing and treating Hashimoto’s thyroiditis

To diagnose Hashimoto’s thyroiditis and create a treatment plan, your doctor will look at your personal and family medical history and carry out a physical examination.

Tell your doctor about your symptoms and let them know if you are taking any other medications as they could be influencing your thyroid hormone levels.

The doctor will look for symptoms like goiter and talk to you about any risk factors that increase your susceptibility to developing the disease.

A blood test will be carried out to monitor your TSH levels. If these are abnormal, your doctor may also test your T3, T4, and thyroid antibody levels. If your T3 and T4 levels are low, you might have an underactive thyroid, while thyroid antibody tests can confirm a Hashimoto’s disease diagnosis.

The doctor may prescribe medication to help return your thyroid hormone levels to normal, and you will need regular TSH testing to ensure you are taking the right dosage.

Most symptoms will ease after several weeks of treatment, but if your goiter is causing complications such as breathing or swallowing difficulties, you might need to have surgery to remove it.

Other treatments

Hashimoto’s thyroiditis flare-ups can also be managed with:

Dietary changes

Your doctor might recommend making changes to your diet to help manage your Hashimoto’s disease flare-ups alongside medication.

A diet consisting of zinc¹⁵, iodine¹⁶, and selenium¹⁷ is essential for keeping your thyroid healthy. Protein-rich foods like meat, dairy, nuts, and seafood are excellent sources of zinc and selenium, while iodine is also available in table salt, animal protein, and some vegetables.

It can be challenging to keep track of the mineral content in your food, so you might want to consider specific diets, including:

  • Paleo diet: This diet emphasizes the importance of lean meats, seafood, vegetables, nuts, and seeds while eliminating dairy, processed foods, and grains.

  • Vegetarian/vegan diet: Diets rich in vegetables that avoid meat and/or animal products are recommended because they contain compounds that have immunomodulatory and anti-inflammatory¹⁸ effects.

  • Gluten-free diet: A 2015 report¹⁹ revealed a strong correlation between wheat sensitivity and autoimmune disorders. Gluten is found in wheat products, barley, and rye.

  • Goitrogen-free diet: Goitrogens²⁰ (the name is derived from goiter) are compounds that can disrupt your thyroid hormone balance. The chemicals are found in vegetables like cabbage, broccoli, and cauliflower.


Taking supplements²¹, including zinc, selenium, vitamin A, B-group vitamins, vitamin D, magnesium, and iron, can counter any nutritional imbalance and ease inflammation by reducing thyroid antibodies.

Remember to speak to your doctor before you start taking any supplements.


Studies²² have found a strong relationship between gut bacteria, the immune system, and thyroid function. The metabolic rate slows down in people with Hashimoto’s disease, which can cause bad bacteria to overgrow, leading to severe gastrointestinal infections. Probiotic supplements contain helpful bacteria that restore balance and help keep your gut healthy.

Probiotics can also be found in cheese, yogurt, and other fermented drinks.

What is hormone replacement treatment?

Hormone replacement treatment is a type of medication and exists in two forms:

  1. FDA-approved synthetic levothyroxine is a prescription-only drug containing a measured amount of thyroid hormone. The measurement is precise because too much or too little levothyroxine can cause severe side effects.

  2. Desiccated thyroid extract (DTE) is a prescription-only treatment that is rarely used, as the synthetic alternative is usually preferred. This treatment is made from animal thyroid glands.

You can discuss the effectiveness and suitability of different treatment options with your doctor.

The lowdown

Hashimoto’s thyroiditis is an autoimmune condition that occurs when your immune system attacks your thyroid, the gland at the front of your neck that releases thyroid hormone into your bloodstream.

The condition can cause hypothyroidism (underactive thyroid) as well as several other complications, including goiter (enlarged thyroid), heart complications, and infertility.

Medication and dietary changes can successfully treat Hashimoto’s thyroiditis and reduce your risk of complications, so early diagnosis is important. Hashimoto’s can run in the family, and you are more at risk if you are female.

If you think you might be having a Hashimoto’s thyroiditis flare-up and have symptoms like unexplained weight gain, fatigue, hair loss, and constipation, speak to your doctor to get a diagnosis.

  1. Hashimoto's disease | NIH: National Institute of Diabetes and Digestive and Kidney Diseases

  2. Thyroid hormone action on skin (2011)

  3. Hypothyroidism and arthritis: Understanding the link | CreakyJoints

  4. Pregnancy and fertility in thyroid disorders | British Thyroid Foundation

  5. Thyroid hormone signaling controls hair follicle stem cell function (2015)

  6. The link between thyroid function and depression (2012)

  7. Stress management in women with Hashimoto’s thyroiditis: A randomized controlled trial (2019)

  8. Drugs that suppress TSH or cause central hypothyroidism (2010)

  9. Hypothyroidism after head and neck radiation | American Head and Neck Society

  10. Thyroid peroxidase antibody (TPO) as a predictor of radiation induced thyroid dysfunction among nurses and technicians working In Mansoura specialized medical hospital: Cross sectional study (2019)

  11. Hashimoto thyroiditis | Medline Plus

  12. Gender differences in autoimmune disease (2014)

  13. The prevalence of autoimmune disorders in women: A narrative review (2020)

  14. Hashimoto thyroiditis (2021)

  15. Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence (2011)

  16. Zinc as a gatekeeper of immune function (2017)

  17. Should we treat subclinical hypothyroidism in obese children? (2016)

  18. Selenium supplementation for Hashimoto's thyroiditis: Summary of a cochrane systematic review (2014)

  19. Evaluation of qualitative dietary protocol (Diet4Hashi) application in dietary counseling in Hashimoto thyroiditis: Study protocol of a randomized controlled trial (2019)

  20. High proportions of people with nonceliac wheat sensitivity have autoimmune disease or antinuclear antibodies (2015)

  21. Goitrogen (2009)

  22. The importance of nutritional factors and dietary management of Hashimoto’s thyroiditis (2020)

  23. Thyroid-gut-axis: How does the microbiota influence thyroid function? (2020)

Have you considered clinical trials for Hashimoto's disease?

We make it easy for you to participate in a clinical trial for Hashimoto's disease, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Discover which clinical trials you are eligible for

Do you want to know if there are any Hashimoto's disease clinical trials you might be eligible for?
Have you taken medication for Hashimoto's disease?
Have you been diagnosed with Hashimoto's disease?