The Symptoms, Causes, Diagnosis, and Treatment of Hashitoxicosis

Hashitoxicosis (Htx) is a common stage in Hashimoto’s thyroiditis. To understand these conditions, it's helpful to review the function of the thyroid. The thyroid gland is a small, butterfly-shaped organ that sits at the base of your neck, and it’s a part of your body’s endocrine system. The primary function of the gland is to produce hormones that govern your metabolism and help convert food into energy.

While sometimes there is no known reason as to why your thyroid might over-function (hyperthyroidism) or under-function (hypothyroidism), other times it can be due to an autoimmune process called autoimmune thyroiditis. This is one of the most common causes of thyroid dysfunction around the world, according to one review in the journal Thyroid Research & Practice.  

In cases of autoimmune thyroiditis, the body’s immune system misfires and creates antibodies that attack the gland. When a person has autoimmune thyroiditis, such as Hashimoto's, they may cycle through an initial period where there is too much thyroid hormone in the body and demonstrate symptoms of hyperthyroidism. This is called hashitoxicosis.

Hashitoxicosis symptoms
Illustration by Jessica Olah, Verywell


The thyroid gland affects nearly all critical functions of the body, including respiration, heart rate, brain function and mood, the development of the nervous system. It also helps regulate weight management, cholesterol levels, energy and strength, skin, hair, and eye health, menstrual cycles, gastrointestinal function, and even more.

The amount of functions the thyroid performs serves as an indicator of the issues that could arise if it malfunctions. The signs and symptoms of Htx may appear very similar to mild to moderate cases of hyperthyroidism. These signs and symptoms might include:

  • Presence of a hard but painless goiter
  • Sweating
  • Tremoring hands
  • Increased appetite
  • Difficulty sleeping
  • Weight loss
  • Fatigue
  • Intolerance to heat
  • Irregular or fast heartbeat
  • Feelings of nervousness or irritability
  • Changes in mood
  • Increase in the frequency of bowel movements or diarrhea

Additionally, Htx is typically self-limiting, meaning it may eventually resolve on its own. In the journal Cureus, there was one documented case of a 21-year-old man who presented with Htx for two years before developing hypothyroidism.

While this may not be the standard duration that someone experiences the Htx phase, it certainly demonstrates there can be some variability among the length of time people go through this stage.


Htx occurs due to an inflammatory autoimmune process, which destroys thyroid follicles or cells and releases an abundance of thyroid hormones into the bloodstream. This induces a state of hyperthyroidism. The reasons why some people develop autoimmune thyroid diseases in the first place, however, is a little more difficult to answer.

Researchers are unsure about what triggers an autoimmune disease, however, precipitating factors like genetics, exposure to bacteria and viruses, and environmental influences are likely at the top of the list. 

There are also contributing factors that may make you more prone to developing an autoimmune thyroid condition, including sex, age, and personal and family medical history. For example, women are more likely than men to develop autoimmune diseases, and the onset of the illness often occurs in middle age between 40 and 60 years.

Additionally, if you have a family member who’s been diagnosed with an autoimmune thyroid condition, or you’ve already been diagnosed with an autoimmune disease, your chances of having an autoimmune thyroid condition increase, too. 


A diagnosis of Htx may be made using a variety of criteria.

Physical Exam

During a physical exam, your doctor will take a detailed medical history, listen to your symptoms, and evaluate you for clues as to what might be going on. Your healthcare provider may assess whether your reflexes are overactive or underactive, observe skin changes, palpate the thyroid gland, and take your heart rate.

A Thyroid Panel

A thyroid panel consists of various blood tests that look at how well your thyroid gland is functioning; it can aid in the diagnosis of whether you are in a state of hyperthyroidism or hypothyroidism. The doctor might order tests such as thyroid-stimulating hormone (TSH), T4, T3, and an antibody test.

If an antibody test is positive, this may indicate that your immune system is attacking your thyroid gland.

In this case, the symptoms you’ve been experiencing might be due to the presence of autoimmune thyroid disease.

Imaging Tests

Additionally, imaging tests can be an integral part of determining the cause of thyroid issues. Your physician may order other tests (like an ultrasound or a thyroid scan) if nodules are found or the size and shape of your thyroid need to be more closely assessed.

Typically, the tests are done by a technician, and a radiologist will review the findings and provide your doctor with a report.


In most instances, medications are used to manage Htx.


If the condition is caught in an active phase, beta-blockers may be used, which can treat some of the symptoms caused by the increased production of thyroid hormones. This is at least until the condition resolves or a state of hypothyroidism develops.

Antithyroid Drugs

Another option your physician might consider are antithyroid drugs, which gradually block the thyroid’s ability to make hormones. However, some of the drugs can be hard on the liver, so talk to your doctor about the risks and benefits of each medication.

Radioactive Iodine

When taken orally, radioactive iodine is absorbed by the thyroid gland, causing the gland to shrink in size. Over time, your Htx symptoms may subside, but the drug can lead to hypothyroidism and you may be required to take thyroid replacement medication permanently.

Ultimately, when choosing a treatment that’s right for you, your doctor will take into account your age, medical history, symptoms, test results, overlapping medical conditions, and the degree in which Htx is affecting your life. If you have questions regarding your test results or your treatment, be sure to talk with your doctor about your concerns. 

A Word From Verywell

Any type of thyroid condition can make you feel unwell. In addition, your treatment may need to be adjusted periodically to keep you feeling your best. The good news is that with medications and proper monitoring of Htx, you can reach a point of stability.

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Article Sources
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  • Johns Hopkins Medicine. Thyroid Gland.

  • National Institute of Diabetes and Digestive and Kidney Diseases. Hyperthyroidism (Overactive Thyroid).

  • Shahbaz A, Aziz K, Umair M, Sachmechi I. Prolonged Duration of Hashitoxicosis in a Patient with Hashimoto’s Thyroiditis: A Case Report and Review of Literature. Cureus. 2018 Jun; 10(6): e2804. DOI: 10.7759/cureus.2804

  • Unnikrishnan AG. Hashitoxicosis: A clinical perspective. Thyroid Research & Practice. 2013; 10(4): 5-6.