Thyroid Drugs Side Effects

Thyroid drugs are used for the treatment of an overactive or underactive thyroid and are meant to increase or block thyroid hormone production. Thyroid problems cause a variety of side effects depending on the severity of the thyroid imbalance. Medications should be taken under the supervision of an endocrinologist in order to ensure that the medication and dosages are correct. Side effects occur in many medications and allergic reactions such as rashes, vomiting and hives should be immediately reported to the physician.

Beta Blockers

• These medications act to block the body's reaction to the symptoms of hypothyroidism and work to reduce the heart rate. Beta-blockers help reduce tremors, agitation and nervousness, which are common symptoms of an overactive thyroid and are given as pills or tablets to take daily. These do not act to treat the hyperthyroidism and are often used in unison with other medications. Beta-blockers are not without side effects, including cold extremities, fatigue, dry mouth, dryness in the eyes, skin dryness, lack of strength and dizziness. Some patients who take beta-blockers begin to have too slow of a heartbeat. Although these are less common side effects, there is also the possibility of having swollen hands or feet, difficulty sleeping, problems breathing, abdominal pain, joint pain, depression and problems with bowel movements. Any side effects should be reported to a physician to see if it is the right medication.

Propylthiouracil (PTU) and Methimazole (Tapazole)

• Propylthiouracil (PTU) and methimazole (Tapazole) are both anti-thyroid drugs that block the production of thyroid hormones. It can take months for the medication to begin working effectively. The primary side effect is an itchy rash on the skin that may cover a small portion of the body. If the rash begins to spread, a doctor should be notified. Other common side effects include hair loss, nausea, vomiting, joint or muscle pain and headaches, as well as loss of taste. Patients who take PTU also suffer from a decrease in white blood cells, a weakened immune system, and even liver problems or jaundice. If a patient is on PTU, her endocrinologist will recommend regular blood tests to monitor white blood cell count. If someone is easily bruised or bleeds more easily, it is important for the physician to be notified.

Iodine or Lugol's Solution

• Iodine medication prevents the release of hormones from an overactive thyroid. Iodide must be used with anti-thyroid medications because the iodine can increase the amount of thyroid hormone and worsen hyperthyroidism. The primary side effects include nausea and a metallic taste.

Hypothyroidism and Medication

• The side effects for thyroid replacement therapy medication are quite similar to severe cases of hypothyroidism. A physician will closely monitor thyroid levels to ensure that it is the right dosage of medication. Patients with known or suspected heart disease, angina or arrhythmia should only be given hormone replacements as a treatment for hypothyroidism with close monitoring and beginning at low dosages. The heart is greatly affected by changes in hormone levels, so the function of the heart is often influenced by the amount of hormones in the body.

L-thyroxine (Synthroid, Levoxyl, Levothroid, Unithroid)

• This group of medications are commonly used in thyroid hormone replacement therapy and is a synthesized form of thyroxine. Side effects often include change in body temperature, fever, change in appetite, changes in heart rate, difficulty breathing, mood swings, loss of hair, weakened bones, tremors, problems menstruating and abdominal pain/nausea.

L-triiodothyronine (Cytomel and Triostat)

• This medication is rarely used alone as thyroid hormone replacement. Its use can cause a sudden rise in T3 production, which can be dangerous for those with heart problems and in the elderly. This drug is often used in combination with L-thyroxine medications. Side effects include insomnia, headache, cramping in the legs, tremors, agitation, change in menstruation cycles, change in body temperatures, diarrhea, appetite changes and shifts in weight.