NutriStack
Levothyroxine and Magnesium Citrate, timing-sensitive.
Magnesium-containing products can interfere with levothyroxine absorption when taken together. The best evidence is for magnesium antacids and other cation-containing agents, but magnesium citrate still delivers magnesium ions in the gut. Taking them together can make thyroid levels harder to control.
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At a glance
- Substances
- Levothyroxine and Magnesium Citrate
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Emerging
- 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 · Emerging evidence
Timing Sensitive
What is happening. Magnesium-containing products can interfere with levothyroxine absorption when taken together. The best evidence is for magnesium antacids and other cation-containing agents, but magnesium citrate still delivers magnesium ions in the gut. Taking them together can make thyroid levels harder to control.
Mechanism. Magnesium ions may complex with levothyroxine in the intestinal lumen and reduce the free drug available for absorption. Magnesium antacid effects on gastric pH may add to this problem for some formulations.
Recommendation. Separate magnesium citrate from levothyroxine by at least 4 hours. Keep the timing consistent and check thyroid labs if you start or stop regular magnesium use.
Minimum separation. 240
Sources (2)
- Liwanpo L, Hershman JM. Conditions and drugs interfering with thyroxine absorption. Best Pract Res Clin Endocrinol Metab. 2009;23(6):781-792. PMID 19942153
- Skelin M, Lucijanic T, Amidzic Klaric D, Resic A, Bakula M, Liberati-Cizmek AM, Gharib H, Rahelic D. Factors Affecting Gastrointestinal Absorption of Levothyroxine: A Review. Clin Ther. 2017;39(2):378-403. PMID 28153426
Stack Score
How this pair moves the number.
Effect on the composite score
If both Levothyroxine and Magnesium Citrate 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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