Does drinking milk around the time of my levothyroxine dose reduce its absorption, and how long should I wait before or after taking it to have dairy?

Quick answer

Yes milk and other dairy products can reduce how well levothyroxine is absorbed if taken close in time to your dose. To minimize this, take levothyroxine on an empty stomach with water and wait at least 30–60 minutes before eating, and keep calcium-containing products (including dairy and calcium supplements) separated by about 4 hours from your levothyroxine. ^{[1] [2]}

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Why dairy can interfere

Levothyroxine (synthetic thyroid hormone T4) is best absorbed in a fasting state. Food in general, and certain components like fiber and soy, can reduce its absorption. ^[3] When levothyroxine is taken with breakfast, thyroid-stimulating hormone (TSH) levels tend to rise and vary more, suggesting reduced absorption and less stable dosing. ^[4]

Calcium is a key reason dairy can interfere: calcium can bind levothyroxine in the gut and lower the amount absorbed. Controlled studies show that co‑administering levothyroxine with different calcium salts reduces absorption by about 20–25%. ^[5] Because milk and yogurt contain calcium, taking them too close to your dose can have a similar effect. ^[5]

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Recommended timing

• Take levothyroxine once daily on an empty stomach with a full glass of water, ideally 30–60 minutes before breakfast. This timing improves absorption and helps keep TSH within the target range. ^{[6] [4]}
• Separate calcium-containing products (calcium supplements, antacids, and dairy foods) from levothyroxine by about 4 hours to avoid absorption problems. ^[2]
• If mornings are difficult, another option some people use is consistent bedtime dosing, but be aware TSH may be modestly higher compared with fasting morning dosing; consistency and monitoring are key. ^[4]

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Practical strategies

• Morning routine: keep levothyroxine on your nightstand, take it as soon as you wake with water, and set a 30–60 minute “breakfast buffer” before coffee or food. ^[1]
• Dairy planning: enjoy milk, yogurt, or cheese later in the day, ensuring a 4‑hour window on either side of your levothyroxine dose. ^[2]
• Supplements: schedule calcium and iron at a different time than your thyroid pill; these are frequent culprits in reduced absorption. ^[2]
• Consistency: take levothyroxine the same way every day; if your routine changes (e.g., adding daily smoothies with dairy), let your clinician know so your dose can be reassessed if needed. ^[1]

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What happens if timing isn’t ideal?

If levothyroxine is routinely taken with food or close to dairy/calcium, absorption may be reduced and your TSH can drift higher, potentially leading to symptoms of under‑replacement (fatigue, weight gain, cold intolerance). Returning to fasting dosing and separating calcium/dairy can help bring levels back to the intended range; your clinician might check labs and adjust the dose if necessary. ^{[4] [1] [2]}

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Key takeaways

• Dairy can reduce levothyroxine absorption due to its calcium content. ^[5]
• Take levothyroxine on an empty stomach; wait 30–60 minutes before eating. ^[6]
• Keep all calcium sources including milk and supplements at least 4 hours away from your dose. ^[2]
• Consistent timing leads to more stable thyroid levels. ^[4]

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Reference timing guidance at a glance

• Fasting administration improves absorption. ^[3]
• Breakfast or bedtime dosing leads to higher, more variable TSH compared to fasting dosing. ^[4]
• Calcium co‑administration lowers levothyroxine absorption by ~20–25%. ^[5]
• Separate calcium-containing products by 4 hours; take levothyroxine 30–60 minutes before breakfast with water. ^{[1] [2] [6]}