Underactive Thyroid Symptoms & Treatment

Updated March 13, 2018

An underactive thyroid, or hypothyroidism, occurs when the thyroid fails to produce the required hormones. Hypothyroidism is diagnosed with a simple blood test and is treated with synthetic hormones. An underactive thyroid eventually causes several symptoms in the body. As with any condition, the symptoms are general and may have a number of causes. It is important to discuss any of the symptoms with a doctor, particularly if the symptoms are new.


Fatigue is a major symptom of an underactive thyroid.

Weight Gain

An underactive thyroid often results in unexplained weight gain. Individuals with an underactive thyroid may have difficulty losing weight.

Muscles & Joints

An underactive thyroid may cause aches, tenderness, stiffness or weakness in muscles. Joints may also experience pain, swelling or stiffness.


Depression can be a result of an underactive thyroid. The thought process may also slow down.


Goitre, or an enlarged thyroid, may be a symptom of an underactive thyroid if left untreated. This enlargement is caused by the body stimulating the thyroid to release more hormones.

Other Symptoms

An underactive thyroid may also cause constipation, pale or dry skin, puffiness in the face, heavier menstrual periods, brittle nails or hair, a hoarse voice, sensitivity to cold temperatures and increased cholesterol levels.


An underactive thyroid is typically treated with a synthetic thyroid hormone. This daily pill replaces the hormones that the thyroid is no longer producing. The synthetic hormone will cause the symptoms to gradually disappear.

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About the Author

Based in the Midwest, Shelley Frost has been writing parenting and education articles since 2007. Her experience comes from teaching, tutoring and managing educational after school programs. Frost worked in insurance and software testing before becoming a writer. She holds a Bachelor of Arts in elementary education with a reading endorsement.