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Certain foods, such as a fiber-enriched diet or soy-based foods, can make levothyroxine therapy less effective. If you have been prescribed this thyroid medication for an underactive thyroid gland (hypothyroidism), please continue reading to learn more foods to avoid when taking levothyroxine.

What blocks the absorption of levothyroxine?

Many drugs, supplements, and foods can interfere with the absorption or effectiveness of levothyroxine. The presence of these foods, dietary supplements, and medications in the gastrointestinal tract can prevent levothyroxine absorption into the body and make it less effective for hypothyroid patients. 

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What foods interfere with thyroid medication?

Eating a meal high in certain foods can interfere with thyroid medication by preventing its absorption from the gut. To avoid altered intestinal absorption of your thyroid hormone replacement, take levothyroxine several hours before or after these foods, supplements, and medications.

Foods to avoid when taking levothyroxine:

• Dietary fiber (high-fiber foods include fresh fruits, vegetables, and whole grains)
• Soy protein (tofu, soy milk, miso, edamame)
• Walnuts
• Cottonseed meal
• Grapefruit and grapefruit juice
• Other fruit juices, such as apple juice and orange juice
• Calcium-rich foods (dairy products, whey protein, cooked leafy greens, sardines)
• Iron-rich foods (soybean, tofu, cooked spinach, organ meat, beef, sardines)
• Caffeinated beverages (tea, coffee)

Supplements to avoid when taking levothyroxine:

• Calcium supplements (calcium citrate and calcium carbonate)
• Iron supplements or multivitamins that contain iron
• Fiber supplements
• Biotin supplements do not affect thyroid hormone levels, but can affect the results of thyroid function tests. These should be stopped at least one week before laboratory testing for thyroid function.

Medications that can have interactions with levothyroxine:

• Antacids that contain calcium, magnesium, or aluminum
• Certain medicines used to treat stomach ulcers, such as sucralfate (Carafate)
• Certain cholesterol-lowering drugs, such as cholestyramine (Prevalite), colestipol (Colestid), and colesevelam (Welchol)
• Phosphate binders such as sevelamer (Renvela, Renagel)
• Cation-exchange resins such as sodium polystyrene sulfonate (Kayexalate)

Levothyroxine interactions with other drugs can also affect how well it works. A potential interaction between your medications can put you at an increased risk of serious adverse effects. Give your healthcare provider a complete list of all your medications, including prescription drugs, over-the-counter medications, dietary supplements, and herbal products, before starting levothyroxine therapy.

What can affect levothyroxine’s effectiveness?

In addition to the drug-food interactions listed above, people with certain health conditions may have poor intestinal absorption of levothyroxine, thereby canceling its effect. For example, malabsorptive disorders such as celiac disease, inflammatory bowel disease, atrophic gastritis, Helicobacter pylori (H. pylori) infection, and lactose intolerance can affect levothyroxine absorption from the gut. 

Can certain diets affect thyroid hormone levels?

Thyroid hormones are made by the thyroid gland under the direction of the pituitary gland in the brain. The food you eat does not affect the natural production of thyroid hormones in the body. In other words, there is no specific diet you can eat to increase thyroid hormone levels. There are also no foods that you should specifically avoid to improve thyroid function if you have hypothyroidism (underactive thyroid). 

We do know that getting enough iodine through dietary sources is essential for normal thyroid function. In developed countries such as the US, iodine deficiency is extremely rare because this mineral is added to salt and food. Therefore, most adults and children who eat a balanced diet do not need to take iodine supplements. Indeed, taking too much iodine can lead to hyperthyroidism (overactive thyroid). 

Doctors also advise against taking large amounts of certain other supplements, such as soy. However, these supplements do not affect thyroid hormone production if your body has enough iodine.

If you have an underactive thyroid gland (hypothyroidism), your doctor may prescribe thyroid hormone replacement in the form of a medication such as levothyroxine. You should take levothyroxine on an empty stomach first thing in the morning. 

How does levothyroxine help with thyroid gland condition?

Levothyroxine is a prescription medication that is used to provide thyroid hormone replacement in people with hypothyroidism (underactive thyroid gland). This is a condition in which the thyroid gland does not make enough thyroid hormones. 

Hypothyroidism symptoms may include fatigue, low energy levels, weight gain, cold intolerance, joint pain, muscle pain, dry skin, thinning hair, irregular menstruation, depression, and slowed heart rate. 

Learn about the 8 signs you may have a thyroid condition.

Levothyroxine administration, in combination with surgery and radioactive iodine therapy, is also used to treat thyroid cancer.

How to take thyroid hormones (levothyroxine)?

If you have been prescribed levothyroxine for hypothyroidism, take the prescribed dose once daily in the morning on an empty stomach, at least 30-60 minutes before breakfast. 

Follow your healthcare provider’s dosing instructions carefully. Your doctor will recommend dose adjustments based on the results of your thyroid function tests and other factors, such as the side effects of levothyroxine. Do not switch between different brands of levothyroxine without your doctor’s approval, as they may contain slightly different amounts of thyroid hormone. Find out some signs that your thyroid medication is not working.

In case of a missed dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule.

Keep all your medical and lab appointments for regular blood tests while taking levothyroxine. 

Frequently Asked Questions

Can I eat eggs after taking levothyroxine?

You should take levothyroxine first thing in the morning, with a full glass of water, on an empty stomach. After that, you can eat most breakfast foods, including eggs, 30-60 minutes after you take levothyroxine. 

Can I have milk after taking levothyroxine?

Calcium-rich foods such as milk, cheese, and yogurt (dairy products) can affect how much levothyroxine your body absorbs. Reduced absorption can prevent the medication from raising the levels of thyroid hormones in your body. It is best to wait 4 hours after your levothyroxine dose before eating calcium-rich foods.

How soon can I drink coffee after taking levothyroxine?

You should wait at least 30-60 minutes after taking levothyroxine before drinking coffee. 

Note: A systematic review of studies found that the liquid form of levothyroxine is stable in beverages such as milk, tea, black coffee, coffee with milk, and orange juice. Also, the liquid form is absorbed faster from the gut compared to the tablet form. Therefore, taking levothyroxine in liquid form may lower the risk of drug-food interactions.

Can I drink alcohol with levothyroxine?

Alcohol use does not affect how levothyroxine works. However, drinking alcohol while taking levothyroxine could make side effects such as headaches, sweating, and flushing worse.