Can Hypothyroidism Cause Bad Breath (Halitosis)?

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Bad breath, also known as halitosis, can be an embarrassing problem for some. Indeed, it’s estimated that halitosis affects over 50% of the population. Bad breath has different causes, including poor oral hygiene, certain foods, smoking, and underlying health conditions. Is hypothyroidism – an underactive thyroid –  one of those conditions contributing to halitosis? Let’s explore that question. 

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Bad breath most often results from the production of volatile sulfur compounds (VSCs) in the mouth. You’ll frequently notice the presence of VSCs first thing in the morning upon waking (aka morning breath). Normal bacteria in the mouth produce VSCs. Often, this results from the reduction of saliva in the mouth caused by mouth breathing or food residue. VSCs may be produced in excess in those with poor oral hygiene, gingivitis, and periodontal disease, among other causes.

While bad breath is most commonly caused by problems in the mouth, about 10 to 20% results from other causes, including the following:

• Strong-smelling foods like garlic, onions, and coffee can leave a lingering odor in your mouth, contributing to bad breath. These odors can persist even after brushing and flossing.
• Smoking and other tobacco products can not only stain your teeth and increase your risk of oral cancer but also cause bad breath. Tobacco products can leave a lingering odor in your mouth and contribute to gum disease, both of which can result in halitosis.
• Medical conditions – such as allergies, respiratory infections, diabetes, liver disease, acid reflux, and autoimmune disease, including Sjögren’s syndrome – can also cause bad breath. These conditions can affect the chemicals in your breath or reduce saliva production, leading to halitosis.
• A diet high in sugary and starchy foods can promote bacterial growth in your mouth, leading to bad breath. Additionally, skipping meals can cause a decrease in saliva production, contributing to dry mouth and halitosis.

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Hypothyroidism occurs when the thyroid doesn’t produce enough thyroid hormone. This hormone plays a major role in regulating metabolism, energy levels, and various bodily functions. So, when thyroid hormone levels are low, body systems tend to slow down. Hypothyroidism can lead to a range of symptoms, including:

• Constipation
• Fatigue
• Weight gain
• Dry skin
• Muscle pain or weakness
• Hair loss

Bad breath is not a typical symptom of hypothyroidism. However, some studies and anecdotal evidence suggest a potential link between the two. The connection between the two may lie in the effects of hypothyroidism on various bodily processes.

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Saliva helps keep your mouth healthy. Your salivary glands make saliva, which helps to:

• Break down food, making it easier to swallow and chew
• Rinse away food from your teeth
• Fight tooth decay
• Help prevent mouth and throat infections

So, a saliva deficiency could have serious consequences for your health. Furthermore, it can contribute to mouth odor. Reduced saliva production can create an environment prime for bacterial overgrowth in the mouth, leading to bad breath.

Hypothyroidism can reduce saliva flow, leading to dry mouth (xerostomia). It isn’t uncommon to have a dry mouth every once in a while. However, persistent dry mouth may be a sign of an underlying medical condition, such as hypothyroidism. Other possible causes of dry mouth include:

• Side effects of medications such as ones taken for high blood pressure and depression
• Radiation therapy
• Cancer treatments
• Sjögren’s syndrome - an autoimmune disease that causes dry mouth (discussed in the next section)
• Damage to the nerves in salivary glands
• Alcohol or tobacco use

Persistent dry mouth can lead to long-term consequences. It can make chewing or swallowing difficult and raise the risk of tooth decay and mouth infections. Tooth decay can lead to cavities, and cavities generally lead to fillings. Mercury fillings may further contribute to hypothyroidism symptoms. Read more about the link between mercury fillings and hypothyroidism here.

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Autoimmune Hashimoto’s thyroiditis – the primary cause of hypothyroidism in the U.S. – is also related to dry mouth. The connection between an autoimmune disease like Hashimoto’s and halitosis is due to the effects of inflammation on the body. Inflammation caused by autoimmune diseases can affect various parts of the body, including the mouth and throat. When inflammation occurs in the oral cavity, it can lead to dry mouth, gum disease, and bacterial growth, all of which can contribute to bad breath.

Furthermore, some autoimmune diseases can directly impact an individual's oral health. For example, Sjögren’s syndrome is an autoimmune disease that primarily affects the salivary glands, leading to dry mouth. This lack of saliva can create an environment where bacteria thrive, leading to halitosis.

Sjogren’s syndrome is characterized by the immune system attacking the glands that produce tears and saliva, leading to dry eyes and mouth. Hashimoto’s thyroiditis, on the other hand, is characterized by the immune system attacking the thyroid gland, leading to an underactive thyroid or hypothyroidism.

Research indicates that Sjögren’s syndrome is more common in people with Hashimoto’s thyroiditis. At the same time, Sjögren’s patients have a higher risk of thyroid issues, as shown in a meta-analysis in 2019.

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Hypothyroidism slows down metabolism, which means all body systems slow down. In your GI tract, slower than normal food movement can result in digestion and nutrient absorption issues. This altered metabolic state may lead to GI issues, such as constipation and acid reflux.

Acid reflux, specifically chronic acid reflux known as GERD, can contribute to bad breath. It occurs when stomach contents flow back up your food pipe (esophagus). Stomach contents contain stomach acid and undigested food bits, which can contribute to bad breath. Acid reflux can also lead to a breakdown of the tooth enamel. This breakdown increases the risk of cavities and poor oral hygiene.

Besides bad breath, other symptoms of GERD include:

• Heartburn
• Sour or bitter taste in the mouth
• Burping
• Chronic, dry cough

Furthermore, a common, chronic bacterial infection in the GI tract known as H.pylori can co-exist with GERD. For most, H. pylori doesn’t cause an infection. But for those that do develop an H. pylori infection, it can cause symptoms including:

• Bad breath due to the production of two major sulfate compounds
• Bloating
• Mild nausea that resolves with vomiting
• Lack of appetite
• Weight loss
• Burping

After undergoing treatment for H. pylori, you can expect a decrease in the severity of bad breath. H. pylori treatment often involves antibiotics and a proton pump inhibitor (PPI) such as Nexium (esomeprazole) or Prilosec (omeprazole). (Remember that you should take these medications several hours apart from thyroid medications to ensure proper absorption. You can also take gel capsules or liquid forms of levothyroxine, like Tirosint and Tirosint-SOL, designed to withstand interference from PPI drugs.) 

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Individuals with hypothyroidism may experience changes in oral health. We have already discussed ways hypothyroidism can cause tooth decay.

Hypothyroidism may also influence the health of your gums. Inflammation of the gums in the early stages is known as gingivitis. Symptoms of gingivitis include red or swollen gums that may easily bleed. Gingivitis can lead to periodontitis. When periodontitis occurs, the gums start to pull away from the tooth, the bone around the tooth can break down, and the teeth may fall out.

Gingivitis and periodontitis fall under the category of periodontal disease. Periodontal disease comes with warning signs, and bad breath that won’t go away is often one of the first signs.

Hypothyroidism can also contribute to snoring and mouth breathing at night. So, instead of breathing through your nose while sleeping, you breathe through your mouth. Mouth breathing increases your risk of tooth decay and gum disease. As we now know, these conditions can contribute to bad breath.

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According to the American Dental Association, the first step in managing your bad breath is determining what is causing it. Schedule a visit to your dentist’s office. They can help determine if your oral health is the cause. If your dentist finds nothing abnormal during your oral exam, your primary care provider can check for other causes. This could include going over all the medications you take. The easiest way to do this is to make a list and give it to your provider. This way, you don’t have to remember what medications you take. Don’t forget to include vitamins and herbal supplements you take on the list!

In addition to managing the underlying condition, maintaining good oral hygiene is essential for fending off bad breath. This includes:

• Brushing your teeth two times a day for at least 2 minutes
• Using a fluoride-containing toothpaste
• Swishing with a mouth rinse or mouthwash after each brushing
• Flossing at least once a day
• Cleaning your tongue at least once a day
• Staying well hydrated and drinking plenty of water throughout the day to keep your mouth moist
• Visiting your dentist regularly for routine cleanings and check-ups

If you suffer from dry mouth, artificial saliva can help increase saliva flow. Some also find chewing sugarless gum or sucking sugar-free sour candies can help with dry mouth symptoms.

If hypothyroidism is the underlying cause of your bad breath, your provider will start you on thyroid hormone replacement medication. These medications help raise your thyroid hormone levels, allowing body functions to return to normal. By doing so, bad breath and other symptoms of hypothyroidism will resolve.

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There is no direct evidence to suggest that hypothyroidism directly causes bad breath. Hypothyroidism symptoms and the effects of this condition can lead to bad breath. Dry mouth, changes within your GI tract, and oral health implications can all play a role in halitosis for individuals with hypothyroidism.

Addressing the underlying thyroid disorder and maintaining good oral hygiene can help manage bad breath. If you’re concerned about persistent halitosis or other symptoms, talk with a healthcare provider for personalized advice and treatment.

If you need a thyroid provider, consider partnering with Paloma Health. Our thyroid providers specialize in treating hypothyroidism, helping to alleviate your symptoms. Please schedule a free telehealth consultation today.

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Does hypothyroidism cause bad breath?

There's no direct evidence that hypothyroidism causes bad breath on its own. However, effects of the condition, like dry mouth, changes in the GI tract, and oral health problems, can all contribute to halitosis.

Why does an underactive thyroid cause dry mouth?

Hypothyroidism can reduce saliva flow, leading to dry mouth (xerostomia). Since saliva helps rinse away food, fight tooth decay, and prevent infections, lower saliva production can allow bacteria to build up and contribute to bad breath.

Is there a connection between Hashimoto's and dry mouth conditions like Sjogren's syndrome?

Yes. Research shows that Sjogren's syndrome, an autoimmune disease that affects the salivary glands, is more common in people with Hashimoto's thyroiditis, and Sjogren's patients also have a higher risk of thyroid issues.

Can acid reflux from hypothyroidism cause bad breath?

Yes. Hypothyroidism slows the GI tract, which can lead to acid reflux. Stomach acid and undigested food flowing back up the esophagus can contribute to bad breath and also wear down tooth enamel over time.

How can I manage bad breath related to hypothyroidism?

Good oral hygiene, including brushing, flossing, and cleaning your tongue daily, along with staying hydrated, can help. If hypothyroidism is the underlying cause, starting thyroid hormone replacement medication can help resolve bad breath along with other symptoms.