NutriStack
Coffee and Levothyroxine, timing-sensitive.
Coffee significantly reduces levothyroxine absorption when consumed within 60 minutes of taking the medication. Chlorogenic acids and tannins in coffee bind directly to levothyroxine molecules, forming poorly absorbed complexes. Studies show coffee can reduce T4 absorption by 29-36% in different populations, potentially leading to subtherapeutic thyroid hormone levels and worsening hypothyroid symptoms. Liquid levothyroxine formulations may be less affected.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Coffee and Levothyroxine
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Strong evidence
Timing Sensitive
What is happening. Coffee significantly reduces levothyroxine absorption when consumed within 60 minutes of taking the medication. Chlorogenic acids and tannins in coffee bind directly to levothyroxine molecules, forming poorly absorbed complexes. Studies show coffee can reduce T4 absorption by 29-36% in different populations, potentially leading to subtherapeutic thyroid hormone levels and worsening hypothyroid symptoms. Liquid levothyroxine formulations may be less affected.
Mechanism. Coffee's chlorogenic acids and tannins form chelation complexes with levothyroxine in the stomach and small intestine, reducing its solubility and absorption. Coffee also accelerates gastric emptying and intestinal transit, reducing the time available for levothyroxine absorption in the duodenum and jejunum where it is primarily taken up.
Recommendation. Take levothyroxine with water only and wait at least 60 minutes before drinking coffee. This timing separation is sufficient to prevent the interaction. If unable to wait 60 minutes, discuss liquid levothyroxine formulations with your prescriber, as these may be less affected by coffee. Decaffeinated coffee has the same effect as it is the non-caffeine compounds that bind levothyroxine.
Minimum separation. 60
Sources (2)
- Benvenga S et al. Altered intestinal absorption of L-thyroxine caused by coffee. Thyroid. 2008;18(3):293-301. PMID 18341376
- Ross DS. Treating hypothyroidism is not always easy: When to treat subclinical hypothyroidism, TSH goals in the elderly, and alternatives to levothyroxine monotherapy. Journal of Internal Medicine. 2022. PMID 34766382
Stack Score
How this pair moves the number.
Effect on the composite score
If both Coffee and Levothyroxine are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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