Does eating cheese around the time I take levothyroxine reduce its absorption?

Eating cheese close to the time you take levothyroxine can reduce how well the medicine is absorbed, mainly because calcium and food in general can interfere with levothyroxine uptake from your gut. To keep your thyroid levels steady, it’s best to take levothyroxine on an empty stomach and separate it from calcium-rich foods like cheese by several hours. ^{[1] [2]}

Why cheese can interfere

• Calcium binds levothyroxine in the intestine, forming complexes that are not absorbed well. This effect has been clearly shown with calcium supplements and applies by extension to calcium-rich foods such as cheese. ^{[3] [4]}
• In controlled studies, co-administering levothyroxine with calcium (500 mg elemental) reduced levothyroxine absorption by about 20–25%, which is enough to shift thyroid blood tests and symptoms for some people. ^[4]
• Food itself lowers and delays levothyroxine absorption, and taking the tablet with breakfast (even without supplements) led to higher, more variable TSH levels compared with fasting dosing. ^[2]

What official guidance recommends

• Take levothyroxine on an empty stomach, 30–60 minutes before breakfast to improve absorption. ^[5]
• Keep levothyroxine at least 4 hours apart from calcium-containing products, including calcium supplements and antacids; this timing rule is commonly applied to calcium-rich foods as well when absorption issues are suspected. ^{[3] [6]}

Practical timing tips

• Morning option: Take levothyroxine with water upon waking; wait 30–60 minutes before eating, and avoid cheese or other calcium-rich foods for at least 4 hours after the dose. ^{[5] [3]}
• Evening option: Take levothyroxine at bedtime, at least 2–3 hours after your last meal, and still try to keep a 4‑hour gap from calcium supplements or heavy dairy intake. Note that bedtime dosing can work, but some people still see slightly higher TSH than with true fasting morning dosing. ^{[2] [3]}

Other foods and drinks to watch

• Certain foods (soy products, high-fiber foods, walnuts) and drinks like grapefruit juice can also decrease or delay levothyroxine absorption, so consistent timing and separation help maintain stable levels. ^{[7] [1]}

What to do if you already took them together

• If you occasionally ate cheese close to your dose, a one‑off interaction is unlikely to cause major issues, but repeated overlap can lead to higher TSH and symptoms of under-replacement (fatigue, weight gain, feeling cold). Consider adjusting timing going forward and ask your clinician about checking TSH if this has been a regular pattern. ^[2]

Key takeaways

• Yes cheese can effectively reduce levothyroxine absorption if taken around the same time, largely due to its calcium content and the general effect of food on absorption. ^{[4] [2]}
• Aim for empty-stomach dosing and separate levothyroxine from calcium (including dairy) by ~4 hours for best consistency. ^{[5] [3]}

Would you like help planning a dosing schedule that fits your routine while keeping a safe gap from dairy and supplements?