What Are Some Side Effects of a Low Thyroid?

Low thyroid stimulating hormone levels, or TSH, causes symptoms of hypothyroidism, including fatigue, constipation, increased sensitivity to cold, dry skin and a puffy face, according to Mayo Clinic. Other symptoms include hoarseness, elevated blood cholesterol levels, muscle weakness, and stiffness, tenderness or aching in the muscles.

Additional symptoms caused by low thyroid levels include swelling, stiffness and pain in the joints, notes Mayo Clinic. Other symptoms include thinning hair, impaired memory, depression, lowered heart rate, and irregular or heavier-than-normal menstrual periods.

Many people with low levels of thyroid hormone do not notice symptoms at first or attribute them to the natural process of aging, advises Mayo Clinic. As the condition progresses, however, the metabolism continues to decline, causing more symptoms and signs of thyroid hormone deficiency.

Left untreated, hypothyroidism can lead to the development of a goiter, which is an enlargement of the thyroid gland, notes Mayo Clinic. Although rare, long-term lack of treatment for hypothyroidism can lead to myxedema, a life-threatening condition marked by decreased body temperature, decreased breathing, lowered blood pressure and coma.

Treatment for the condition involves replacement of TSH using synthetic thyroid hormone replacement medication, reports Mayo Clinic. Typically, lifetime replacement therapy is necessary. Some medications include Synthroid and Levothroid.