Fatigue

• 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

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

Goiter

• Goiter, 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.
  
  

Treatment

• 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.