NutriStack
Aluminum/Magnesium Hydroxide and Doxycycline, timing-sensitive.
Aluminum and magnesium in antacids chelate doxycycline in the gut, dramatically reducing its absorption. Bioavailability reductions of 50 percent or more are typical with concurrent dosing. Subtherapeutic doxycycline can cause treatment failure for infections such as Lyme disease, rickettsial illness, or community-acquired pneumonia.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Substances
- Aluminum/Magnesium Hydroxide and Doxycycline
- 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. Aluminum and magnesium in antacids chelate doxycycline in the gut, dramatically reducing its absorption. Bioavailability reductions of 50 percent or more are typical with concurrent dosing. Subtherapeutic doxycycline can cause treatment failure for infections such as Lyme disease, rickettsial illness, or community-acquired pneumonia.
Mechanism. Al3+ and Mg2+ chelate the beta-diketone system of tetracyclines, forming insoluble complexes that are not absorbed across the intestinal epithelium.
Recommendation. Take doxycycline at least 2 hours before or 6 hours after any aluminum or magnesium hydroxide antacid. Do not co-administer.
Minimum separation. 360
Sources (2)
- Gugler R, Allgayer H. Effects of antacids on the clinical pharmacokinetics of drugs. An update. Clin Pharmacokinet. 1990;18(3):210-219. PMID 1969784
- Eljaaly K, Helal A, Almandeel T, Algarni R, Alshehri S. Multivalent cations interactions with fluoroquinolones or tetracyclines: A cross-sectional study. Saudi J Biol Sci. 2021;28(12):6929-6932. PMID 34866992
Stack Score
How this pair moves the number.
Effect on the composite score
If both Aluminum/Magnesium Hydroxide and Doxycycline 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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