Hyperthyroidism and acid reflux can occur together. Although acid reflux is not a symptom of hyperthyroidism, there may be a link between the two.

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Hyperthyroidism causes the thyroid to produce too much thyroid hormone. This speeds up many metabolic reactions and can cause a person to feel anxious, experience heart palpitations, and become sensitive to heat. In some cases, it can also cause muscle weakness.

In theory, this can affect the esophagus and digestive tract, potentially causing stomach acid to travel the wrong way. A 2015 case report identifies at least one time this has occurred. However, no well-designed recent scientific research has shown that acid reflux is a typical hyperthyroidism symptom or complication.

Read on to learn more about hyperthyroidism, acid reflux, and the link between the two.

Hyperthyroidism is a disorder that causes the thyroid to produce too much thyroid hormone. This hormone helps regulate metabolism and nutrient absorption.

People with hyperthyroidism have a wide range of symptoms, which may include:

  • increased appetite
  • weight loss
  • being very sensitive to the heat or frequently feeling hot
  • anxiety
  • irregular or fast heartbeat
  • muscle weakness
  • tremors
  • loose stools
  • shortness of breath

While many conditions can cause hyperthyroidism, Graves’ disease is the most common. This autoimmune disease damages the thyroid, causing it to produce too much thyroid hormone.

Acid reflux, or heartburn, occurs when stomach acid flows back up the esophagus. A person may feel a burning sensation, burp frequently, or experience throat pain or hoarseness. It is more common after an acidic meal, and a person may experience more intense symptoms when lying down.

If acid reflux is chronic, it is known as gastroesophageal reflux disease (GERD).

Doctors do not fully understand what causes it, but many risk factors can contribute to its development. These include problems with the digestive muscles, hiatal hernia, smoking, excessive drinking, and pregnancy.

Occasional acid reflux is not usually dangerous. However, chronic gastroesophageal reflux can damage the esophagus.

There is not a clear, well-documented connection between acid reflux and hyperthyroidism. The two conditions do not share similar causes or risk factors. While there is a theoretical explanation for the link between the two, research has not proven a causal link.

In theory, hyperthyroidism could affect digestion, causing acid reflux.

This is because digestion requires the muscles of the digestive system to work well together. Hyperthyroidism may cause muscle weakness, especially without treatment.

Another theory posits that hyperthyroidism treatment may cause acid reflux. Radioactive iodine treatment can prevent the thyroid from producing excessive thyroid hormone. This, in turn, may contribute to reflux.

A 2015 case report emphasizes that these symptoms are rare, though they do occur.

The report details the experience of a 61-year-old male who presented with heartburn and hyperthyroidism. An examination of his esophagus showed weak muscle tone and other abnormalities. These symptoms improved after doctors treated his hyperthyroidism.

Acid reflux is not a typical symptom of hyperthyroidism, but this report suggests it can happen. Despite this, researchers have not identified how often it occurs.

The same is true for the theory that hyperthyroidism treatment causes acid reflux.

A 2016 study followed 137 people undergoing radioiodine treatment for thyroid cancer. Nearly half (44.74%) reported heartburn after taking the medication. Higher doses of radioactive iodine also correlated with a higher rate of side effects, including acid reflux.

However, like the previous study, this link is an association, and researchers have not found a causal link between the conditions.

Learn more about thyroid and other cancers in our dedicated hub here.

Treatment for hyperthyroidism focuses on reducing the amount of thyroid hormone in the bloodstream. There are three main treatment options:

  • A person may take radioactive iodine to reduce the thyroid hormone the thyroid produces.
  • A person can take anti-thyroid medications to reduce the thyroid hormone in the bloodstream.
  • A person can take beta-blockers to control their hyperthyroid symptoms.
  • In severe cases, a surgeon can remove the thyroid via a thyroidectomy. This will require a person to take synthetic thyroid hormones for the rest of their life.

Antacids can help treat occasional acid reflux. Prescription drugs such as proton pump inhibitors may help with more chronic cases.

Some people may need surgery to manage either acid reflux or to treat other complications, such as damage to the esophagus and esophageal strictures.

Learn about TSH testing to check thyroid hormone levels here.

A person should contact a doctor if:

  • They have hyperthyroidism and are experiencing acid reflux symptoms.
  • They have chronic acid reflux.
  • Their acid reflux gets worse while treating thyroid disease.
  • They have symptoms of thyroid disease.
  • They experience unpleasant side effects from thyroid medication.

Acid reflux is not a common or typical symptom of hyperthyroidism. However, it may occur due to hyperthyroidism complications, such as muscle weakness.

People with acid reflux and hyperthyroidism should see a doctor and not assume their symptoms are due to hyperthyroidism. Other conditions, such as gastroesophageal reflux disease or a hiatal hernia, may better explain acid reflux. These conditions require treatment.

People taking medication for thyroid disease or acid reflux should discuss their symptoms and medication regimen with a doctor before adding additional medications, including over-the-counter antacids.