← All Medications

Levothyroxine Food Interactions

Brand names: Synthroid, Tirosint, Levoxyl, Unithroid

Thyroid Hormone Replacement

2
High Risk
1
Moderate
🥛 Calcium-Rich Foods & Supplements (Dairy, Fortified OJ, Calcium Tablets) ⚠️ High Risk

Calcium binds to levothyroxine in the intestines, blocking its absorption by up to 40%. Taking levothyroxine near calcium-rich foods or supplements means your body receives far less thyroid hormone than prescribed.

How it works

Calcium forms an insoluble complex with levothyroxine in the GI tract, dramatically reducing oral bioavailability.

What to do: Take levothyroxine on an empty stomach 30-60 minutes BEFORE breakfast. Wait at least 4 hours after taking levothyroxine before eating dairy products or calcium supplements.
Source: FDA Synthroid Prescribing Information; Endocrine Society Clinical Practice Guidelines
☕ Coffee / Espresso ⚠️ High Risk

Coffee significantly reduces levothyroxine absorption — even black coffee with no additives. Studies show coffee can reduce absorption by 25-57%, undermining your thyroid therapy.

How it works

Polyphenols and other coffee compounds interfere with intestinal levothyroxine absorption at the transport level.

What to do: Do NOT drink coffee for at least 30-60 minutes after taking levothyroxine. Many endocrinologists recommend waiting a full 60 minutes.
Source: Endocrine Practice Journal: Coffee and Levothyroxine Absorption Study
🌾 High-Fiber Foods (Bran, Flaxseed, Soybean Flour) ⚡ Moderate

Very high-fiber foods and fiber supplements can bind to levothyroxine and reduce its absorption, requiring higher doses to achieve thyroid hormone targets.

How it works

Dietary fiber physically traps levothyroxine molecules in the GI tract, preventing intestinal absorption.

What to do: Maintain a consistent fiber intake. If increasing fiber, TSH levels should be rechecked.
Source: FDA Synthroid Prescribing Information; American Thyroid Association Guidelines
Disclaimer: Educational purposes only. Based on FDA drug labeling and NIH MedlinePlus. Consult your pharmacist or physician before changing your diet while on medication.