What Happens If You Leave Hypothyroidism Untreated?

If you have hypothyroidism, you’re not alone. In fact, about 5 out of every 100 people in the U.S. have it. Fortunately, it’s easy to correct for most people. But leaving hypothyroidism untreated can cause trouble. That’s because your thyroid gland affects almost every one of your bodily functions. 

When your thyroid gland is underactive, it can be tough to put the signs together to recognize the issue. And without treatment, an underactive thyroid can cause serious mental and physical health problems. 

Let’s take a closer look at what happens if you leave hypothyroidism untreated and at the most common complications.

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What happens if you leave hypothyroidism untreated?

Untreated hypothyroidism can lead to serious mental and physical health problems. Let’s review the complications of untreated hypothyroidism below.

Mental health changes

Hypothyroidism affects your mind as well as your body. It can slow your thoughts, make you forgetful, and affect your ability to concentrate. In fact, hypothyroidism is one of the reversible causes of dementia. 

Not having enough thyroid hormone puts a damper on your emotional well-being too. You could experience more mood swings and irritability. People with hypothyroidism might be more likely to have anxiety and depression. If you already suffer from depression, being hypothyroid can make it harder to treat. 

Goiter

An underactive thyroid might become enlarged (goiter). Goiters are usually painless lumps in the front of your neck. They can cause you to cough, make your voice hoarse, and affect your breathing and swallowing. If the goiter is small and doesn’t cause symptoms, it may not need to be treated. Treatment, if necessary, usually consists of medication or surgery.

Heart disease

Having an underactive thyroid can increase your risk of heart disease. It can have a direct effect on the heart, making it beat slower and less efficiently. And it also has an effect on the coronary arteries, affecting proper blood flow. This raises the risk of coronary artery disease and congestive heart failure. If you have heart disease already, hypothyroidism can make it worse.

Nerve damage

Long-term hypothyroidism can damage nerves. You might feel symptoms like:

• Pain

• Numbness

• Tingling

• Weakness, most commonly in the hands 

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The nerves of the hand travel through a narrow channel in the wrist called the carpal tunnel. Carpal tunnel syndrome can result from hypothyroidism causing inflammatory changes in the tunnel. This can hurt the nerves inside. Nerve damage from untreated hypothyroidism can also cause hearing loss.

Is untreated hypothyroidism life-threatening?

If severe hypothyroidism isn’t treated for a long time, it can be life-threatening. Myxedema coma can happen when the body systems slow down so much that you’re left in a coma. Even with treatment, many people don’t survive. The good news is that it’s easy to detect and treat hypothyroidism, so getting to this point is very rare.

What are the primary causes of hypothyroidism?

Hypothyroidism occurs when the thyroid doesn’t make enough thyroid hormone to meet the body’s needs. While it can affect anyone (including children), people over the age of 60 are at especially high risk. Other important risk factors are listed below.

Medications

Certain medications can affect your thyroid hormone levels. Some common ones are:

• Lithium

• Amiodarone (Pacerone)

• Bexarotene (Targretin)

• Birth control pills and menopausal hormone therapy

• Antidepressants (like sertraline)

• Anti-seizure medicines (like carbamazepine, phenytoin, and phenobarbital)

Thyroid surgery

A thyroidectomy is a procedure where you have all or part of your thyroid removed. After a thyroidectomy, it’s possible that the remaining tissue may not produce enough thyroid hormones for your body. In some cases, you may still have thyroid tissue in place after thyroid surgery. But what’s left might not be able to make enough hormones for your body.

A history of hyperthyroidism

Hyperthyroidism is an overactive thyroid. It can have just as many health consequences as an underactive thyroid, and it needs treatment as well. Previous treatment for hyperthyroidism or burnout of an overactive thyroid gland can eventually lead to low thyroid hormone levels. Also, an overactive thyroid can burn itself out over time and have a hard time producing thyroid hormone.

Radiation to areas around the thyroid

Radiation for treatment of head and neck cancers can damage the thyroid gland as a side effect. The same radiation beams that kill the cancer cells can also damage the body’s normal tissues. This can lead to your thyroid gland functioning poorly, resulting in hypothyroidism.

Family history of hypothyroidism

Hypothyroidism tends to run in families. You have a higher chance of developing hypothyroidism if your family members have it — specifically close family members like parents, grandparents, or siblings.

Pregnancy 

The hormonal changes during pregnancy can cause changes to the thyroid gland. Pregnancy also makes you more likely to develop autoimmune thyroid issues. You can also develop autoimmune thyroid issues after pregnancy — where your immune system attacks your thyroid gland. Postpartum thyroiditis is an autoimmune condition much like Hashimoto’s thyroiditis (where the body attacks and creates antibodies against the thyroid). It can occur up to 1 year after pregnancy.

An autoimmune condition

Having one autoimmune disease increases your chances of getting another one — like autoimmune hypothyroidism. Autoimmune diseases include conditions like: 

• Type 1 diabetes

• Rheumatoid arthritis

• Celiac disease

• Alopecia areata (hair loss)

• Vitiligo (loss of skin color)

• Pernicious anemia (decrease in red blood cells). 

Iodine deficiency

Not getting enough iodine in your diet (iodine deficiency) can lead to thyroid issues. That’s because without iodine, the thyroid gland can’t make thyroid hormone. 

Iodine deficiency is a global problem. However, it’s rare in the U.S., because iodine is added to salt and other foods. 

How does untreated hypothyroidism affect fertility and pregnancy?

Hypothyroidism can affect your fertility and make it harder to get pregnant. It can make your period irregular, which means you won’t be able to track ovulation. Or it can prevent you from ovulating altogether. The good news is that if hypothyroidism is causing you to be infertile, it can be easily treated. Studies show that over 75% of women who couldn’t conceive due to hypothyroidism were able to get pregnant after getting treatment.

During pregnancy, insufficient thyroid hormone can be dangerous for both the mother and the baby. And there’s a higher risk of miscarriage. You may also be at risk of other pregnancy complications like: 

• High blood pressure

• Anemia (low red blood cell count)

• Bleeding (hemorrhage)

• Placental abruption (early separation) 

Higher levels of thyroid hormones are needed to meet the demands of pregnancy. Without treatment, hypothyroidism can affect the baby’s development. There might be a higher risk of complications, like: 

• Preterm birth

• Low birth weight

• Respiratory distress

• Stillbirth

In addition, studies have found that the IQ scores of children born to hypothyroid mothers can be lower than those born to mothers with normal thyroid hormone levels. While this may sound scary, the risks to moms and babies are avoidable with the right treatment. 

How is hypothyroidism treated?

Hypothyroidism isn’t curable, but it’s totally correctable. Synthetic thyroxine is recommended for hypothyroidism. It mimics the hormones released by your thyroid gland. The most common synthetic thyroxine medication used to treat hypothyroidism is levothyroxine (L-thyroxine, Synthroid, Levoxyl, Levothroid, Tirosint, and Unithroid). 

The dose depends on factors like:

• Thyroid hormone level

• Age

• Weight

• Medical history

• Gender

A healthcare professional will estimate your starting dose and watch your thyroid hormone levels. They’ll make adjustments if they need to. 

How do you know if you’re on the right dose of thyroid medication?

A healthcare professional will monitor your thyroid levels regularly to find the right medication dose for you. This can take some adjustment. If your TSH is too high while taking your thyroid medications, your dose might have to be increased. If it’s too low, your dose may be reduced. 

Your prescriber might also change your dose because of symptoms you might be having. Fatigue, cold sensitivity, and dry skin can suggest that your dose is too low. Meanwhile, shakiness, irritability, and weight loss can suggest that your dose is too high. The right dose should eliminate symptoms. 

Lastly, the right dose for you can change over time. Make sure to have regular follow-ups with your prescriber to ensure that your thyroid symptoms are controlled and your hormone levels are where they should be.

Can hypothyroidism go away without treatment?

Most people with hypothyroidism will need to take levothyroxine for life. But if your hypothyroidism is due to other conditions that are reversible, it may improve. Common causes of hypothyroidism that can go away include:

• Pregnancy

• Medications 

• Autoimmune thyroiditis

• Iodine exposure

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Written by:

Maryann Mikhail, MD

Maryann Mikhail, MD, is a board-certified dermatologist and medical writer based in South Florida. She is the founder of Waverly DermSpa in Fort Lauderdale and holds a voluntary faculty position at the Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery at the University of Miami MIller School of Medicine.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Farzon A. Nahvi, MD

Dr. Nahvi is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works clinically at Concord Hospital in Concord, New Hampshire, and is a clinical assistant professor of emergency medicine at the Geisel School of Medicine at Dartmouth. Prior to this, he worked as an ER physician and clinical assistant professor of emergency medicine at the Mount Sinai Health System, NYU Langone Health, NYC Health + Hospitals/Bellevue, and the Manhattan VA. He is a graduate of Cornell University and NYU School of Medicine.

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