Your thyroid produces hormones that control the rate your body uses energy -- known as your metabolism. If you have an underactive thyroid gland, called hypothyroidism, your doctor may prescribe a synthetic thyroid hormone replacement medication called levothyroxine. You'll need to take levothyroxine every day, most likely as a lifelong treatment. Certain foods, vitamins and chemical compounds can interfere with the absorption of levothyroxine, especially vitamin supplements high in iron and calcium. Levothyroxine is sold under a variety of brand names, including Synthroid, Levoxyl and Unithroid. Levothyroxine replaces T4 hormone, one of two important hormones -- T3 and T4 -- that control metabolism. Your body can synthesize T3 hormones from levothyroxine even if you are hypothyroid, so there is rarely a need to supplement both T3 and T4 hormones. In addition to a slower metabolism and weight gain, common symptoms of a sluggish thyroid include fatigue, headaches, a sensitivity to cold, depression and a goiter -- a physical swelling of the thyroid gland at the base of your throat.
Levothyroxine is designed to be absorbed in your intestines during digestion. Any drugs that interfere with digestion can block the absorption of your hormone replacement. The Mayo Clinic notes that iron supplements and vitamins that contain iron, calcium supplements, antacids containing magnesium and aluminum and certain cholesterol and ulcer medications can stop your body from assimilating levothyroxine. You do not have to stop taking your supplements or other medications, but you must wait four hours after taking levothyroxine to avoid any potential interactions. While there are no vitamin supplements designed to be taken with levothyroxine, the University of Maryland Medical Center notes that some vitamins may help relieve the symptoms of your hypothyroidism. UMMC recommends eating whole foods, rather than taking supplements to increase your consumption of foods high in B vitamins, such as whole grains and fresh vegetables and fruits and vegetables high in antioxidants, such as blueberries, cherries, bell pepper, squash and tomatoes.
Omega-3 supplements may decrease inflammation and strengthen your immune system. You can also increase omega-3 intake by eating fatty cold-water fish, walnuts and flaxseeds. Any vitamin supplement that you and your doctor agree should be added to your diet can be taken with levothyroxine, provided that you don't take your vitamin or supplement within four hours of taking your thyroid replacement hormone. Fiber supplements and high fiber foods should also be taken well after the levothyroxine has been absorbed by your body. Certain foods, including walnuts, cottonseed meal and soybean flour may also interfere with levothyroxine and should be eaten later. Foods or Things to Avoid When Taking Levothyroxine Breakfast Meal Plan for Hypothyroidism Bad Side Effects of Synthroid Can I Take Thyroxine With Calcium With D? Losing Weight While on Synthroid Diet Menu Plan for an Underactive Thyroid A List of Foods That You Can Eat with Gastritis Natural Thyroid Treatments to Help You Lose Weight
The Best Supplements for Low Thyroid How to Diet With Synthroid Levothyroxine & Fish Oil Foods to Avoid When Taking Thyroid Medication Effects of Too Much Levothyroxine Is There Concern With Taking Magnesium With Levothyroxine? Weight Loss With Levothyroxine Medication Iron Supplements & Levothyroxine Foods to Eat When You Have Thyroid Disease How is Thyroxine Used for Weight Loss?Levothyroxine is the generic form of Synthroid, a synthetic thyroid hormone. It is a replacement for a hormone that is naturally produced by your thyroid gland to regulate the body’s energy and metabolism. Levothyroxine is used to treat hypothyroidism, enlargement of the thyroid, thyroid cancers, pituitary disorders and low thyroid hormone production due to surgery, radiation and medication use. This drug may interact with other medications, as well as certain foods and beverages. Consumption of levothyroxine with certain foods can significantly reduce its absorption.
Thyroid hormones levels can decrease if you take your medication with foods -- or foods that contain -- soybean flour, cotton seed meal, walnuts, dietary fiber, calcium or calcium fortified juices. These foods should be avoided within several hours of taking your medication. In addition, thyroid hormone levels may increase if you fast while on this medication. To avoid such fluctuations, levothyroxine should be administered on a consistent schedule, with regard to time of day and relation to meals, per your doctor's orders. Levothyroxine can impair the efficacy of oral hypoglycemic agents and insulin, substances used for diabetics for blood glucose control. It may cause hypoglycemia, glucose intolerance, new-onset diabetes mellitus or exacerbation of preexisting diabetes, therefore interfering with your blood glucose control. It is important for your physician to closely monitor your blood glucose levels if you are taking drugs for hypoglycemia. Supplements, especially those containing calcium or iron, are problematic with levothyroxine.
Taking calcium at the same time as levothyroxine can have a significant impact on thyroid hormone levels. According to the Marin Medical Society, the administration of levothyroxine with calcium can reduce hormone levels by 40 percent. This causes a decreased oral bioavailability of levothyroxine, drug binding and alterations in gastric pH, thus the intended pharmacologic effects of this drug are reduced. It is recommended that you take levothyroxine at least four hours before or after other supplements, such as iron or multivitamin with minerals. But check with your doctor to see if you should continue your supplement regimen. Antacids, when taken with levothyroxine, may decrease the oral bioavailability of this thyroid hormone medication. While the mechanism of interaction is unknown, it is thought to involve nonspecific absorption of levothyroxine in the gastrointestinal tract, thus reducing the effects of levothyroxine. The worst offenders are antacids containing magnesium, aluminum, calcium and iron.
It is recommended that take antacids at least four hours apart from when you take levothyroxine. Otherwise, you may require an increase dosage of levothyroxine during antacid use. Taking iron, especially as a dietary supplement, has the potential to decrease the bioavailability and pharmacologic effects of levothyroxine. This interaction is thought to be a result of binding to form highly acidic pH level, creating insoluble complexes that are poorly absorbed in the gastrointestinal tract. Therefore, your thyroid hormone levels will be elevated and not effective. If you separate levothyroxine from iron by at least two to four hours, you may be able to avoid this interaction. Your thyroid hormone levels, however, should be closely monitored. Estrogen interacts with levothyroxine by increasing the concentration of thyroid-binding globulins in your blood. These substances are proteins that attach to thyroid hormone so that it can circulate throughout your body. Consequently, there may be a reduction in unbound or free thyroxine available for hormone production.
Increased thyroid hormone concentrations result. Individuals secrete thyroxine to compensate for this effect; however, people with hypothyroidism lack the mechanism to adapt. If you are on estrogen, your physician should request blood tests to check your levothyroxine levels every 12 weeks and adjust the thyroid dosage accordingly. If you experience fatigue, cold intolerance, constipation, weight gain, depression, hair loss, joint or muscle pain, dry skin, abnormal menstrual periods, hoarseness or any other clinical manifestations of hypothyroidism, you should contact your physician immediately. Levothyroxine & Vitamin Supplements Breakfast Suggestions for Patients on Synthroid Are There Vitamins for People Who Take Synthroid Pills? When Taking Synthroid Medicine, Can You Eat Calcium Foods? Does Vitamin B-12 Interfere With Synthroid Medicines? Levothyroxine & High Fiber Diet Synthroid & Kelp Supplements Foods That Prevent the Digestion of Synthroid