Levothyroxine Sodium interactions

Food & lifestyle

• dietary fiber

  Moderate

  Absorption

  Consumption of certain foods as well as the timing of meals relative to dosing may affect the absorption of T4 thyroid hormone (i.e., levothyroxine). T4 absorption is increased by fasting and decreased by foods such as soybean flour (e.g., infant formula), cotton seed meal, walnuts, dietary fiber, calcium, and calcium fortified juices.

  What to do: Preparations containing T4 thyroid hormone should be administered on a consistent schedule with regard to time of day and relation to meals so as to avoid large fluctuations in serum levels. Foods that may affect T4 absorption should be avoided within several hours of dosing if possible. When administered to patients receiving continuous enteral nutrition for more than 7 days, some experts recommend that the tube feeding should be interrupted for at least 1 hour before and 1 hour after the dose of levothyroxine is given and to monitor patients' thyroid function.

  3 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  3. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm 66 (2009): 1438-67

• soybean

  Moderate

  Absorption

  Consumption of certain foods as well as the timing of meals relative to dosing may affect the absorption of T4 thyroid hormone (i.e., levothyroxine). T4 absorption is increased by fasting and decreased by foods such as soybean flour (e.g., infant formula), cotton seed meal, walnuts, dietary fiber, calcium, and calcium fortified juices.

  What to do: Preparations containing T4 thyroid hormone should be administered on a consistent schedule with regard to time of day and relation to meals so as to avoid large fluctuations in serum levels. Foods that may affect T4 absorption should be avoided within several hours of dosing if possible. When administered to patients receiving continuous enteral nutrition for more than 7 days, some experts recommend that the tube feeding should be interrupted for at least 1 hour before and 1 hour after the dose of levothyroxine is given and to monitor patients' thyroid function.

  3 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  3. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm 66 (2009): 1438-67

Conditions

Conditions in which Levothyroxine Sodium needs care, as documented in this source.

• Adrenal Insufficiency

  Major

  The use of thyroid hormones is contraindicated in patients with uncorrected adrenal insufficiency. Thyroid hormones increase tissue demand for adrenocortical hormones and may precipitate acute adrenal crisis. In patients with controlled adrenal insufficiency or other endocrine disorders, therapy for these concomitant disorders may need to be adjusted following thyroid replacement, since hypothyroidism often obscure or diminish the signs and symptoms of these conditions. Clinical monitoring of thyroid and adrenal function as well as any other appropriate endocrine function is recommended during thyroid hormone therapy.

  4 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Cytomel (liothyronine)." Monarch Pharmaceuticals Inc (2001):
  3. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  4. "Product Information. Thyrolar (liotrix)." Forest Pharmaceuticals (2001):

• Cardiovascular Diseases

  Major

  Thyroid hormones cause increases in myocardial contractility and heart rate as a result of increased metabolic demands and oxygen consumption. Therapy with thyroid hormones should be administered cautiously and initiated at reduced dosages in patients with cardiovascular disorders such as angina, coronary artery disease, and hypertension. Clinical monitoring of cardiovascular function is recommended. If chest pain or exacerbation of cardiovascular disease occurs, the dosage of thyroid hormone should be reduced, even at the expense of achieving euthyroid state. Thyroid hormones should not be administered to patients with an acute myocardial infarction that is not complicated by hypothyroidism.

  4 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Cytomel (liothyronine)." Monarch Pharmaceuticals Inc (2001):
  3. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  4. "Product Information. Thyrolar (liotrix)." Forest Pharmaceuticals (2001):

• Graves Disease

  Major

  The use of thyroid hormones is contraindicated in patients with untreated thyrotoxicosis of any etiology, since thyroid hormones may exacerbate the condition.

  4 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Cytomel (liothyronine)." Monarch Pharmaceuticals Inc (2001):
  3. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  4. "Product Information. Thyrolar (liotrix)." Forest Pharmaceuticals (2001):

• Diabetes Mellitus

  Moderate

  Since hypothyroidism often obscure or diminish the signs and symptoms of endocrine disorders such as diabetes mellitus or diabetes insipidus, thyroid replacement therapy may aggravate the intensity of symptoms associated with these conditions. Patients with endocrine disorders should be monitored more closely during thyroid hormone therapy, and their medication regimen adjusted accordingly. If thyroid medication is later discontinued, a downward readjustment of insulin or oral hypoglycemic agent may be necessary in patients with diabetes mellitus to avoid hypoglycemia.

  4 sources

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):
  2. "Product Information. Cytomel (liothyronine)." Monarch Pharmaceuticals Inc (2001):
  3. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  4. "Product Information. Thyrolar (liotrix)." Forest Pharmaceuticals (2001):

• Seizures

  Moderate

  Thyroid hormones may alter the seizure threshold. Seizures have been reported rarely following the initiation of levothyroxine therapy. Therapy with thyroid hormones should be administered cautiously in patients predisposed to seizures.

  1 source

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical (2002):