NutriStack
Calcium and Gabapentin, timing-sensitive.
Calcium-containing antacids and supplements may reduce gabapentin absorption through similar mechanisms as magnesium. The interaction can decrease gabapentin bioavailability enough to affect therapeutic efficacy for neuropathic pain or seizure control.
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At a glance
- Substances
- Calcium and Gabapentin
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Moderate evidence
Timing Sensitive
What is happening. Calcium-containing antacids and supplements may reduce gabapentin absorption through similar mechanisms as magnesium. The interaction can decrease gabapentin bioavailability enough to affect therapeutic efficacy for neuropathic pain or seizure control.
Mechanism. Calcium may reduce gabapentin absorption by altering local GI pH or through binding interactions in the intestinal lumen. Since gabapentin has a saturable absorption mechanism via the L-amino acid transporter, any reduction in the available drug fraction can reduce therapeutic levels.
Recommendation. Separate gabapentin and calcium supplements by at least 2 hours. Take gabapentin at least 2 hours after calcium to minimize any absorption interference.
Minimum separation. 120
Sources (3)
- Yagi T, Naito T, Mino Y, Umemura K, Kawakami J. Impact of concomitant antacid administration on gabapentin plasma exposure and oral bioavailability in healthy adult subjects. Drug Metab Pharmacokinet. 2012;27(2):248-254. PMID 22240839
- Liu C, Kuang X, Li K, Guo X, Deng Q, Li D. Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials. Food & Function. 2020. PMID 33237064
- Yao P, Bennett D, Mafham M et al.. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open. 2019. PMID 31860103
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Gabapentin 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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