Researchers are still investigating the link between smoking and hypothyroidism. Although smoking does appear to affect the thyroid, its exact nature remains controversial.

Experts believe smoking can affect how the thyroid functions. It may also affect conditions related to the thyroid, such as hypothyroidism.

This article discusses how smoking may affect thyroid function and several conditions, including autoimmune thyroid diseases, goiter, and thyroid-related eye problems. It also explores how smoking can affect thyroid cancer and thyroid medication.

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Smoking may affect thyroid function and conditions affecting the thyroid.

One 2019 study investigated smoking and thyroid function in more than 15,000 people. It found that smoking may play a significant role in the development of thyroid dysfunction.

Another 2019 study notes that smoking can lower levels of thyroid-stimulating hormone (TSH). While higher levels of TSH typically indicate hypothyroidism, this does not mean that smoking does not affect hypothyroidism, as it affects the way the thyroid functions.

However, the research also notes that the effect of smoking on thyroid hormones remains controversial. It states that other studies have found different results. More research is needed on exactly how smoking affects the thyroid and related conditions.

Smoking can cause damage to nearly every organ in the body. It can also lead to various conditions, damage overall health, and reduce life expectancy.

Read more about how smoking affects the body.

Smoking can affect several thyroid-related conditions.

Autoimmune thyroid conditions occur when a person’s immune system attacks and damages their thyroid gland. Their thyroid gland cannot then make the right amount of thyroid hormones.

Hashimoto’s disease

Hashimoto’s disease is the most common type of autoimmune condition that causes hypothyroidism. Experts have not yet fully established the effect of smoking on Hashimoto’s disease.

Although Hashimoto’s disease increases a person’s risk of thyroid disease, there is no clear conclusion yet on whether smoking affects this risk.

Learn more about Hashimoto’s disease.

Graves’ disease

Graves’ disease is an autoimmune thyroid disease generally associated with hyperthyroidism. Hyperthyroidism is when the thyroid gland makes too much thyroid hormone.

However, in some rare cases, people with Graves’ disease have switched from hyperthyroidism to hypothyroidism.

Untreated Graves’ disease can cause serious health conditions. Stopping smoking, if applicable, and avoiding secondhand smoke can lower the risk of developing the condition. Smoking can also increase its severity.

Learn more about Graves’ disease.

Goiter occurs when the thyroid gland is enlarged. Hypothyroidism or other conditions can cause goiter.

Although goiters are often harmless, they may indicate a more serious condition requiring treatment.

Smoking can increase a person’s risk of goiter. Tobacco contains:

  • nicotine
  • thiocyanate
  • benzopyrene

These chemicals can reduce thyroid hormones, making a person more likely to develop a goiter.

Learn more about goiters.

Thyroid eye disease (TED) is a common issue for people who have Graves’ disease. It can also sometimes affect people with hypothyroidism, though this is not common.

People with TED generally have several vision problems that worsen over time. In some cases, they may have permanent vision loss.

Researchers are still investigating the link between TED and smoking, although they believe several factors may play a part.

Smoking can:

  • increase the risk of developing TED
  • worsen TED symptoms
  • lower the effectiveness of TED treatments

Learn more about TED.

Smoking is a firmly established cause of various cancers. However, experts disagree on whether it causes thyroid cancer. Several studies have produced inconclusive and contradictory results.

Some experts believe it may decrease the risk of thyroid cancer in males. One study from 2021 found that smoking may have a protective effect on thyroid cancer.

However, the authors of the study noted that their results should be interpreted with caution and that smoking has many other negative effects. They also suggested further studies to investigate smoking and thyroid cancer.

Learn more about thyroid cancer.

Smoking affects thyroid function and the production of thyroid hormones. Healthcare professionals treat hypothyroidism with a prescription medication called levothyroxine.

Levothyroxine is a synthetic version of a hormone called thyroxine. It replaces thyroxine if the thyroid gland cannot produce it.

Research from 2015 suggests taking levothyroxine can reduce the severity of a person’s withdrawal symptoms when they stop smoking. However, more research is needed on the exact effects of smoking on thyroid medications.

There are several support options to help people quit smoking. Counseling may help.

A healthcare professional can recommend appropriate treatments and connect people to programs and resources.

The Centers for Disease Control and Prevention (CDC) also provides information on how to quit smoking, including resources such as:

Read more about ways to quit smoking.

Hypothyroidism is when the thyroid gland does not produce enough thyroid hormones. Although experts believe smoking may reduce levels of thyroid-stimulating hormone (TSH), the exact reasoning for this remains unclear. The link between smoking and hypothyroidism also remains controversial.

Smoking has some effects on other conditions that affect the thyroid, such as Graves’ disease and Hashimoto’s disease. It also has several harmful health effects on various parts of the body. There are many free resources to help people stop smoking.

If an individual is interested in quitting smoking, they can speak with a healthcare professional for tips and support.