Hypothyroidism, also called an underactive thyroid, causes low levels of thyroid hormone in your body. The thyroid gland releases thyroid hormone which controls your metabolism. The gland works in conjunction with the pituitary gland to release the proper amount of this hormone.

When the gland releases too little thyroid hormone, it is called hypothyroidism. Hyperthyroidism occurs when it releases too much.

Symptoms of hypothyroidism

The main symptoms of hypothyroidism are:

The symptoms of an underactive thyroid develop gradually. It may take several months or years before your symptoms become severe enough for you to notice and seek medical attention.

What other health problems does hypothyroidism cause?

In some cases, this condition can cause other health issues. Often, treating your hypothyroidism can resolve these symptoms.

Erectile dysfunction

Hypothyroidism can lead to problems getting or maintaining erections. That's because in some cases, hypothyroidism is caused by issues with your pituitary gland, which also results in lower testosterone levels. Once you address your low hormone levels, you may see improvement with your erectile dysfunction.

Lack of ovulation

Some people with hypothyroidism do not ovulate or ovulate at irregular intervals. This can affect fertility if you are trying to get pregnant.

Pregnancy complications

People who experience untreated hypothyroidism while pregnant may experience complications. This is because a pregnant person's thyroid hormones also get passed to the baby. If the baby doesn't get enough, their brains may not develop properly. This can cause developmental delays once the baby is born.

Pregnant people with untreated hypothyroidism may also be more likely to have miscarriages or go into premature labor.


If your thyroid does not produce enough thyroid hormone, then your pituitary gland may continually send thyroid stimulating hormone (TSH). An overload of TSH can cause your thyroid to grow larger. When this happens, it is called a goiter. Much of the time goiters are not harmful. However, if they are large enough, they can cause difficulty with swallowing or breathing.

Heart disease

Because hypothyroidism leads to higher cholesterol levels, you may be more likely to experience heart disease or heart failure.


Depression or low mood is one of the symptoms of an underactive thyroid. You may notice it getting worse over time. However, depression is not likely to be the only symptom of hypothyroidism.


Myxedema is typically only found in people who have had undiagnosed hypothyroidism for a long time. It is a severe condition that can lead to a lowered body temperature, mental confusion, and even a coma. To avoid myxedema, get your thyroid hormone levels checked if you suspect you have a thyroid issue.


Hyperthyroidism: Symptoms, Treatment, Medication See Slideshow

What causes hypothyroidism?

There are several potential causes of an underactive thyroid.

Hashimoto's disease

This genetic condition causes the immune system to attack your thyroid gland. Once the thyroid is damaged, it can no longer make enough thyroid hormone. Another name for this condition is chronic lymphocytic thyroiditis.

Thyroid inflammation

If your thyroid is inflamed, it may first release too much thyroid hormone for a few weeks or months. Then, it will release too little because it has been depleted. This condition is also called thyroiditis.

Iodine deficiency

The nutrient iodine is added to many types of salt because it is important for thyroid health. Your body needs iodine to create the thyroid hormone.

Treatments for overactive thyroid

If you've had an overactive thyroid in the past, you may have had radiation therapy to damage the thyroid, or you may have had it removed altogether. If you have had either of these treatments, you will need to take synthetic thyroid hormone to avoid symptoms of hypothyroidism.

Treatments for an underactive thyroid

Luckily hypothyroidism is usually easy to treat. Your doctor will likely prescribe a synthetic version of the thyroid hormone. The most popular medication for this is called levothyroxine. You will need to take this medication for the rest of your life. Once you are medicated, your symptoms and complications may reduce greatly or go away completely.

If you are taking medication for an underactive thyroid, it's important to visit your doctor for all follow-up appointments. The amount of medication you need to take may change throughout your life. So, your doctor will check your hormone levels periodically to make sure your current dosage is correct.

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Medically Reviewed on 11/1/2021
American Thyroid Association: "Hypothyroidism in Pregnancy," "Iodine Deficiency."

Cleveland Clinic: "Hypothyroidism," "Thyroiditis."

CLINICAL THYROIDOLOGY FOR THE PUBLIC: "Hypothyroidism and risk for heart disease."

Mayo Clinic: "Hypothyroidism (underactive thyroid)," "Hypothyroidism and infertility: Any connection?" "Thyroid disease: can it affect a person's mood?"

National Institute of Diabetes and Digestive and Kidney Diseases: "Hashimoto's Disease." NHS: "Levothyroxine."