Is smoking bad for my thyroid?

Is smoking bad for my thyroid?

Smoking and Thyroid

We’ve all seen the graphic warnings plastered across cigarette packs: stark images of diseased lungs or cautionary messages like “Smoking Causes Cancer” or “Smoking Kills.” It’s a blunt message, yet over a billion people continue to smoke. Intriguing, right? It is common knowledge that smoking is harmful, but why do people still light up? The reasons are indeed wide and varied. But, how does this apparently everyday lifestyle choice impact something as little as your thyroid?

Did you know, according to research, there is a possible association between smoking and decreased risk of thyroid cancer? This means smokers may be slightly less likely to develop thyroid cancer compared to non-smokers. However, it is important to note that other studies have found that smoking is correlated to certain kinds of thyroid cancer. While the research on smoking and thyroid cancer is interesting, the results remain controversial and inconclusive so far. The reasons behind this potential link remain unclear and require further investigation. 

Health organizations do not recommend smoking to prevent thyroid cancer. This makes sense, as smoking is a major risk factor for lung cancer, heart disease, stroke, and other health problems. These risks far outweigh any potential benefit for thyroid cancer. Moreover, smoking affects thyroid hormone levels and can exacerbate symptoms associated with some thyroid conditions.

So, to answer the question of whether smoking is bad for your thyroid, the simple answer is likely yes. It is bad for your thyroid and overall health. In the rest of this article, we will shed light on why this is so. We will also look at how you can quit smoking and the benefits associated with smoking cessation.

How does smoking affect my thyroid and overall health?

1. Changes in Thyroid Function Tests

Smoking can alter thyroid function tests and consequently affect the interpretation of the test results. In a study published in the Endocrine journal in 2020, researchers investigated the effects of cigarette smoking on thyroid function in over 5,000 euthyroid participants (people with normal thyroid hormone levels). The findings of this study showed that smoking tends to slightly increase levels of thyroid hormones (FT4 and FT3) and decrease TSH levels. Interestingly, when people quit smoking, their blood tests sometimes show a change in their thyroid function as well. TSH levels increase, while T4 levels decrease. However, these changes are usually mild and may not necessarily translate to actual thyroid dysfunction.

2. Increased Risk of Thyroid Autoimmune Response

Research suggests that smoking may trigger an autoimmune response, leading to the production of antibodies that attack the thyroid gland. Smoking has been linked to Graves’ disease, an autoimmune form of hyperthyroidism. Smokers with Graves’ disease might experience more severe symptoms, have a higher risk of thyroid eye disease (also known as Graves’ ophthalmopathy). The relationship between smoking and Hashimoto’s thyroiditis, an autoimmune form of hypothyroidism, is less clear. While some studies suggest smoking might worsen symptoms, others have not found a significant link.

3. Increased Risk of Goiter Formation

Cigarette smoke contains thiocyanate, a compound that disrupts the normal function of the thyroid gland. Thiocyanate competes with iodine for uptake by the thyroid gland. Since iodine is essential for the production of thyroid hormones, thiocyanate can interfere with hormone production. This can potentially lead to an enlargement of the thyroid gland as it tries to compensate for reduced hormone production. In fact, research has shown that the association between smoking and goiter formation is especially high in iodine-deficient populations.

4. Influence on the Effectiveness of Thyroid Medication

Smoking can interfere with the effectiveness of thyroid medications, such as levothyroxine, which may be prescribed to treat hypothyroidism. For those who smoke, their dose of levothyroxine may need to be adjusted to mitigate the effects of smoking on thyroid hormone levels

Research shows that smoking also affects the response to treatment of thyroid-associated ophthalmopathy. In a study published in the British Journal of Ophthalmology, researchers found that people with Graves’ disease who smoke take longer to respond to treatment for thyroid eye disease. Not only is treatment less effective for smokers, but, the more they smoke, the worse the treatment outcome is likely to be.

5. Cardiovascular Disease

Both smoking and thyroid dysfunction are independent risk factors of cardiovascular disease. When combined, they can significantly increase the risk of heart disease, hypertension, and stroke. This is all the more reason why you need to quit smoking if you have been diagnosed with a thyroid disorder.

6. Bone Health

Smoking, as well as thyroid dysfunction, can have negative effects on bone health. Smoking reduces bone density and increases the risk of osteoporosis and fractures. Thyroid hormones are essential for bone metabolism, and imbalances in thyroid function can further worsen bone loss. Individuals with thyroid disorders such as hyperthyroidism who smoke may face a higher risk of osteoporosis and related complications, compared to those who don’t smoke.

7. Impact on Reproductive Health

Smoking has been linked to adverse effects on reproductive health, including menstrual irregularities, infertility, and pregnancy complications. Thyroid disorders, especially hypothyroidism, can also impact fertility and pregnancy outcomes. Smoking, therefore, may worsen the reproductive health effects of thyroid dysfunction. For this reason, smoking cessation is particularly important for women of reproductive age with thyroid disorders.

How do I quit smoking?

If you don’t already smoke, that is great. And if you do, it’s really helpful to be aware that it can be hard to quit. A report from the World Health Organization indicated that in 2018, over 60% of the 1.3 billion tobacco users worldwide expressed a desire to quit, though only 30% had access to appropriate smoking cessation services.

Some people find immediate cessation overwhelming and have more success gradually stepping down their nicotine intake, while others prefer the immediacy of quitting cold turkey. At the end of the day, the best method depends on your smoking habits, health, level of nicotine dependence, and personal preferences. 

However, here are some general tips you should consider if you have decided to quit smoking:

  • Set a quit date: Choose a date to stop smoking and stick to it. Prepare yourself mentally and physically by removing cigarettes, lighters, and ashtrays from your environment. Inform your family and friends about your decision and seek their support.
  • Avoid triggers: Identify situations that increase your urge to smoke. This self-awareness can help you develop strategies to manage these triggers in better ways. A good starting point is making sure to replace old routines that involve smoking with healthier alternatives, such as taking a walk or practicing breathing exercises.
  • Seek support: Surround yourself with supportive people who will encourage your efforts and hold you accountable. There are also online communities and support groups specifically dedicated to helping people quit smoking. Additionally, telephone quitlines are a great resource for immediate assistance.
  • Find healthy substitutes: If you have to, always remind yourself that cravings are temporary. Keeping items like a sugar-free gum can distract your mouth, while fruits and nuts satisfy the hand-to-mouth habit often associated with smoking. These healthier options can help divert your attention from the urge to smoke.
  • Use Nicotine Replacement Therapy (NRT):  If like many others, you find that quitting abruptly is difficult, consider using NRT products like nicotine gums, patches, lozenges, inhalers, or nasal sprays. These can help manage withdrawal symptoms and decrease the urge to smoke by delivering small, steady doses of nicotine without the harmful chemicals found in cigarettes.
  • Consider prescription medications: Medications such as Bupropion (Zyban) and Varenicline (Chantix) can be effective to quit smoking. These drugs require a prescription and can help reduce cravings and withdrawal symptoms. Consult your healthcare provider to see if these medications are appropriate for you, especially if your nicotine dependence level is high.
  • Celebrate each milestone: This is really important. Acknowledge small victories along your quitting journey, no matter how small. Be sure to celebrate these milestones in healthy ways that reinforce your new smoke-free life.

What are some benefits of quitting smoking?

Just to recapitulate some of the points already made in this article, quitting smoking has several benefits for thyroid health, including:

  1. Reduced risk of developing thyroid diseases such as Graves’ disease and thyroid eye disease.
  2. Improvement in thyroid function as thyroid hormone and TSH levels return to normal over time.
  3. Reduced risk of complications (such as cardiovascular disease, osteoporosis, and reproductive health problems) if you already have a thyroid disorder.

Key takeaways

  • Smoking is a well-known risk factor for numerous health problems, including heart disease and lung cancer. 
  • If you have concerns about your thyroid health, consult a doctor. They can assess your symptoms, run blood tests, and determine if smoking might be a contributing factor.
  • Understanding how smoking affects thyroid health is essential for making informed decisions about lifestyle choices and promoting overall well-being.
  • Smoking might alter blood test results and increase the risk of Graves’ disease. Evidence for a direct link of smoking to Hashimoto’s disease is inconclusive.
  • There are numerous available resources you should take advantage of if and when you want to quit smoking. You can also talk to your doctor or a smoking cessation specialist for support.
  • Smoking cessation can be a challenge. It requires dedication and willpower, but the rewards for your overall health, including your thyroid function, are significant.
  • Quitting smoking can lead to improvements in thyroid function, reduce the risk of thyroid disorders, and prevent associated complications.


At ThyForLife, we do our utmost to provide accurate information. For detailed medical information regarding diagnosis, treatment, and general practices please consult your healthcare professional. Always listen to the advice of your healthcare provider.
Share this article

You might also like

Showing most popular and related articles for you

Be the first to get

weekly thyroid related articles and useful tips directly to your inbox!