Thyroid hormones are created in the thyroid gland and serve many functions in the human body, including temperature regulation and basal metabolic rate regulation. They affect the bones and the nervous system as well. The hormones produced by the thyroid gland are triiodothyronone (known as T3); thyroxine (known as T4); and calcitonin. When the body does not produce enough hormone, replacement therapy may be ordered. T3 and T4 may also be used in the management of thyroid cancer and other diseases. Calcitonin is indicated to treat bone problems. Hypothyroidism (low thyroid hormone level) may be treated by natural or synthetic T4 or T3 and T4.
Cardiovascular and Blood-related Side Effects
Cardiovascular and blood-related side effects of T3 and T4 are uncommon and include elevated liver enzymes in the blood, fast heart rate, increased blood pressure, heart failure, irregular heart rhythm, chest pain, heart attack, the sensation of the heart pounding in the chest and life-threatening stoppage of the heart. Careful regulation of thyroid levels can greatly diminish the risk of thyroid hormone side effects.
Neurological Side Effects
Neurological side effects of T3 and T4 are uncommon and include nervousness, irritability, hyperactivity, headache, hand tremors, insomnia, sweating, tiredness, intolerance to heat, anxiety and mood swings. According to Drugs.com, seizures occur rarely when thyroid hormone therapy is begun.
Gastrointestinal Side Effects
Gastrointestinal side effects of T3 and T4 are uncommon and include gagging, choking, narrowing or closing of the esophagus, nausea, abdominal cramps, vomiting, diarrhea and appetite changes.
Skin-related Side Effects
Allergic skin reactions may occur. According to the 2010 Lippincott's Nursing Drug Guide, children may lose some of their hair during the first few months of taking thyroid hormones. Uncommon side effects include flushing and adult hair loss.
Other Side Effects
Other uncommon side effects of T3 and T4 include weight loss, leg cramps, decreased bone mineral density, difficulty breathing, changes in menstrual cycle and fertility problems.
Calcitonin Side Effects
Common side effects of calcitonin include nausea, vomiting, diarrhea, stomach pain, back pain, runny nose, stuffy nose, loss of appetite, metallic taste in mouth, frequent urination, rash, joint pain, headache, flushing of the face and red hands. A severe allergic reaction can also occur, manifested by rash, itching, hives, difficulty breathing and swelling of the face, mouth or tongue. According to the 2010 Lippincott's Nursing Drug Guide, this drug can cause irritation of the nose when inhaled and irritation of the skin and surrounding tissue when injected as a shot.
References
- 2010 Lippincott's Nursing Drug Guide: Liotrix, Levothyroxine Sodium, Thyroid, Dessicated and Calcitonin
- Drugs.com: Synthroid Side Effects
- Mayo Clinic: Thryoid: Side Effects
