Supplement·Interactions·Reviewed June 9, 2026
Calcium interactions.
Calcium has 80 documented interactions in the NutriStack database: 3 to avoid or watch closely, 50 that need timing or caution, and 27 that work synergistically. The full list, with what each pairing does, is below.
In short
Calcium at a glance.
A quick, data-grounded summary. The full table is below.
Calcium has 80 documented interactions in the NutriStack database: 3 to avoid or watch closely, 50 that need timing or caution, and 27 that work synergistically. The full list, with what each pairing does, is below.
Interactions
Everything that interacts with calcium.
Every supplement and medication in the NutriStack database with a documented interaction with this substance, highest-severity first. Open any pair for the mechanism and sources.
| Substance | Interaction | What happens |
|---|---|---|
| Ceftriaxone | Contraindicated | Ceftriaxone and calcium-containing IV fluids can form insoluble ceftriaxone-calcium precipitates in lung and kidney tissue, with fatal cases... details → |
| Iron | Conflict | Calcium significantly inhibits both heme and non-heme iron absorption when taken simultaneously. details → |
| Iron Bisglycinate | Conflict | Calcium significantly inhibits both heme and non-heme iron bisglycinate absorption when taken simultaneously. details → |
| Calcitriol | Caution | Calcium supplements can combine with calcitriol to cause hypercalcemia, hypercalciuria, kidney stones, or soft tissue calcification. |
| Calcium Alpha-Ketoglutarate | Caution | Calcium alpha-ketoglutarate delivers a meaningful amount of elemental calcium (approximately 20-25 percent by weight). Combining it with a separate... |
| Chlorthalidone | Caution | Chlorthalidone is thiazide-like and reduces urinary calcium loss, which can raise serum calcium. High-dose calcium supplements can add to that... details → |
| Digoxin | Caution | Large or repeated calcium supplement doses can cause hypercalcemia in susceptible people, particularly with kidney disease, dehydration, thiazide... details → |
| Esomeprazole | Caution | Esomeprazole reduces absorption of calcium carbonate, which depends on stomach acid to dissolve. Long-term PPI use is associated with a modest but... details → |
| Famotidine | Caution | Famotidine reduces gastric acid and can lower the absorption of calcium carbonate, which depends on acid to dissolve. The fracture-risk signal is... details → |
| Hydrochlorothiazide | Caution | Hydrochlorothiazide reduces urinary calcium excretion and can raise serum calcium. Adding high-dose calcium supplements can increase the risk of... details → |
| Lansoprazole | Caution | Lansoprazole reduces absorption of calcium carbonate, which depends on stomach acid for dissolution. Long-term PPI use is associated with a modest... details → |
| Losartan/Hydrochlorothiazide | Caution | Hydrochlorothiazide decreases urinary calcium excretion; high-dose calcium can contribute to hypercalcemia in susceptible patients. |
| Omeprazole | Caution | Long-term omeprazole use reduces calcium absorption, particularly from calcium carbonate which requires an acidic environment for dissolution. This... details → |
| Pantoprazole | Caution | Pantoprazole, like other PPIs, reduces gastric acidity needed for calcium carbonate absorption. Long-term use may impair calcium balance and has... details → |
| Alendronate | Timing Sensitive | Calcium chelates alendronate and dramatically reduces its already-low bioavailability (0.6-0.7%). Taking calcium within 30 minutes of alendronate... details → |
| Ampicillin | Timing Sensitive | Calcium is a divalent cation that can theoretically chelate beta-lactam antibiotics, and large meals or dairy can reduce ampicillin absorption.... |
| Cefdinir | Timing Sensitive | High-dose calcium supplements and calcium-containing antacids can bind cefdinir in the gut and modestly reduce its absorption through... |
| Cefixime | Timing Sensitive | Calcium-containing supplements and antacids may bind cefixime in the gut, reducing its dissolution and absorption and potentially undermining... |
| Cefpodoxime | Timing Sensitive | Calcium supplements and calcium-containing antacids may reduce cefpodoxime absorption. Cefpodoxime proxetil depends on gastric acidity for adequate... |
| Cefuroxime | Timing Sensitive | Calcium-containing supplements and antacids can chelate cefuroxime and raise gastric pH. Because cefuroxime axetil relies on an acidic stomach... |
| Cholestyramine | Timing Sensitive | Cholestyramine may bind or delay absorption of some supplements when taken simultaneously. |
| Ciprofloxacin | Timing Sensitive | Calcium chelates ciprofloxacin in the GI tract, forming insoluble calcium-quinolone complexes that can reduce ciprofloxacin absorption by up to 90%.... details → |
| Dicloxacillin | Timing Sensitive | Calcium supplements and calcium-rich products can bind oral penicillins in the gastrointestinal tract and, together with food, reduce dicloxacillin... |
| Doxycycline | Timing Sensitive | Calcium chelates doxycycline, forming insoluble tetracycline-calcium complexes that significantly reduce antibiotic absorption. This can reduce... details → |
| Elderberry Zinc Lozenges | Timing Sensitive | High-dose calcium can reduce elderberry zinc lozenges absorption when taken simultaneously. |
| Erythromycin | Timing Sensitive | Polyvalent cations such as calcium can bind to some oral antibiotics and reduce absorption. While erythromycin is less prone to cation chelation... |
| Fosfomycin | Timing Sensitive | Oral fosfomycin tromethamine is a single-dose therapy whose efficacy depends on achieving adequate urinary concentrations. Calcium is a divalent... |
| Gabapentin | Timing Sensitive | Calcium-containing antacids and supplements may reduce gabapentin absorption through similar mechanisms as magnesium. The interaction can decrease... details → |
| Ibandronate | Timing Sensitive | Calcium taken near oral ibandronate can markedly reduce absorption and treatment efficacy. |
| Itraconazole | Timing Sensitive | Calcium supplements, particularly calcium carbonate, raise gastric pH and can substantially reduce the dissolution and absorption of itraconazole... |
| Levofloxacin | Timing Sensitive | Calcium binds levofloxacin in the gut and reduces its absorption by 30 to 50 percent. This applies to calcium supplements, calcium-fortified foods,... details → |
| Levothyroxine | Timing Sensitive | Calcium supplements significantly reduce levothyroxine absorption by 20-25% through chelation in the gastrointestinal tract. This can lead to... details → |
| Magnesium Citrate | Timing Sensitive | High-dose calcium and magnesium compete for absorption when taken simultaneously. details → |
| Magnesium Glycinate | Timing Sensitive | High-dose calcium and magnesium compete for absorption when taken simultaneously. details → |
| Magnesium L-Threonate | Timing Sensitive | High-dose calcium and magnesium compete for absorption when taken simultaneously. details → |
| Magnesium Malate | Timing Sensitive | High-dose calcium and magnesium compete for absorption when taken simultaneously. details → |
| Magnesium Taurate | Timing Sensitive | High-dose calcium and magnesium compete for absorption when taken simultaneously. details → |
| Manganese | Timing Sensitive | High-dose calcium can reduce manganese absorption when taken together, lowering the amount of manganese the body takes up from a given dose. |
| Minocycline | Timing Sensitive | Calcium can reduce oral Minocycline absorption when taken together. |
| Moxifloxacin | Timing Sensitive | Calcium can reduce oral Moxifloxacin absorption when taken together. |
| Penicillin V Potassium | Timing Sensitive | Calcium is a divalent cation that can theoretically bind some oral antibiotics in the gut. For penicillin V the effect on absorption is minimal, but... |
| Phenytoin | Timing Sensitive | Calcium can reduce phenytoin absorption if taken simultaneously. While calcium supplementation may be important for patients on phenytoin (which... details → |
| Psyllium Husk | Timing Sensitive | Psyllium can bind calcium and accelerate intestinal transit, modestly reducing calcium absorption when co-administered. |
| Rabeprazole | Timing Sensitive | Acid suppression may reduce absorption of calcium carbonate more than calcium citrate and long-term PPI therapy is associated with fracture risk. |
| Risedronate | Timing Sensitive | Risedronate forms insoluble chelates with calcium in the gut, which can drop its already low oral bioavailability (~1%) to near zero. Even calcium... details → |
| Spirulina | Timing Sensitive | When spirulina (taken for its iron and mineral content) is co-ingested with a calcium supplement, the calcium reduces absorption of spirulina's... details → |
| Strontium | Timing Sensitive | Strontium and calcium compete for the same intestinal absorption pathway, and calcium is preferentially absorbed, so taking them together... |
| Sucralfate | Timing Sensitive | Calcium supplements can compete for binding and add to the burden of poorly absorbed minerals when taken with sucralfate. |
| Tetracycline | Timing Sensitive | Calcium can reduce oral Tetracycline absorption when taken together. |
| Vitamin D2 | Timing Sensitive | Vitamin D2 increases how much dietary and supplemental calcium the gut absorbs, which is beneficial for bone health at sensible doses but can become... details → |
| Zinc | Timing Sensitive | High-dose calcium can reduce zinc absorption when taken simultaneously. |
| Zinc Carnosine | Timing Sensitive | High-dose calcium can reduce zinc carnosine absorption when taken simultaneously. |
| Zinc Picolinate | Timing Sensitive | High-dose calcium can reduce zinc picolinate absorption when taken simultaneously. |
| Betaine HCL | Synergy | In individuals with reduced gastric acid output, calcium carbonate and similar insoluble calcium salts are poorly absorbed because they require an... |
| Black Cohosh | Synergy | Calcium complements black cohosh in the menopausal setting by supporting bone density, which black cohosh does not address while it relieves... |
| Boron | Synergy | Boron reduces urinary calcium excretion and supports calcium utilization for bone health. |
| Carbamazepine | Synergy | Long-term carbamazepine therapy is associated with adverse bone-mineral effects and higher fracture risk, especially when vitamin D or calcium... details → |
| Cinacalcet | Synergy | Calcium may be used to correct or prevent cinacalcet-related hypocalcemia when prescribed. |
| Dexamethasone | Synergy | Dexamethasone is the most potent oral glucocorticoid. Even short courses significantly impact calcium balance. Supplementation helps preserve bone... details → |
| Fructooligosaccharides (FOS) | Synergy | FOS fermentation may improve calcium solubility and absorption in the colon in some contexts. |
| Galactooligosaccharides (GOS) | Synergy | Prebiotic fermentation may support mineral solubility and absorption, though GOS should not replace adequate calcium intake. |
| L-Lysine | Synergy | L-lysine can enhance intestinal calcium absorption and reduce urinary calcium excretion, supporting calcium retention. |
| Medroxyprogesterone | Synergy | Depot medroxyprogesterone acetate (DMPA) is associated with a measurable but largely reversible decrease in bone mineral density during use.... details → |
| Methylcobalamin | Synergy | Calcium may actually assist B12 absorption. Some evidence suggests calcium helps release B12 from food and supports intrinsic factor binding. |
| Methylprednisolone | Synergy | Like all glucocorticoids, methylprednisolone reduces calcium absorption and increases bone loss. Calcium supplementation is recommended for patients... details → |
| Prednisolone | Synergy | Chronic prednisolone therapy accelerates bone loss and increases fracture risk, especially at higher doses or when used for several months. Calcium... details → |
| Prednisone | Synergy | Prednisone and other corticosteroids significantly deplete calcium through multiple mechanisms, increasing the risk of osteoporosis and fractures.... details → |
| Raloxifene | Synergy | Adequate calcium intake supports bone mineralization while raloxifene reduces bone resorption. |
| Red Clover Isoflavones | Synergy | Calcium adequacy supports bone health goals often targeted during menopause. |
| Silicon | Synergy | Silicon (as orthosilicic acid) added to calcium and vitamin D stimulates markers of bone collagen formation and may improve bone mineral density... |
| Soy Isoflavones | Synergy | Calcium adequacy supports bone-health goals often paired with soy isoflavones. |
| Tenofovir Disoproxil | Synergy | Adequate calcium intake is relevant because tenofovir disoproxil can reduce bone mineral density. |
| Valproic Acid | Synergy | Valproic acid has been linked with lower bone mineral density in people with epilepsy, particularly with longer treatment duration. Adequate calcium... details → |
| Vitamin B12 | Synergy | Calcium may actually assist B12 absorption. Some evidence suggests calcium helps release B12 from food and supports intrinsic factor binding. |
| Vitamin C | Synergy | Vitamin C mildly enhances calcium absorption by maintaining calcium in the soluble, ionized form in the gut. |
| Vitamin C Liposomal | Synergy | Vitamin C Liposomal mildly enhances calcium absorption by maintaining calcium in the soluble, ionized form in the gut. |
| Vitamin D3 | Synergy | Vitamin D3 is essential for calcium absorption from the gut. Without adequate D3, only 10-15% of dietary calcium is absorbed. details → |
| Vitamin K2 | Synergy | K2 activates osteocalcin to direct calcium to bones and matrix GLA protein to prevent arterial calcification. Essential when supplementing calcium. details → |
| Vitamin K2 MK-4 | Synergy | K2 activates osteocalcin to direct calcium to bones and matrix GLA protein to prevent arterial calcification. Essential when supplementing calcium. details → |
| Zoledronic Acid | Synergy | Zoledronic acid rapidly suppresses bone resorption and can drive serum calcium down within days of infusion, especially in patients with low calcium... details → |
Go deeper
The full calcium profile.
Benefits, dosing by goal, forms, and the cited evidence for this supplement.
FAQ
Common calcium questions.
Quick answers drawn from the table above.
What interacts with Calcium?
In the NutriStack database, Calcium has 80 documented interactions with other supplements and medications. The most notable include Ceftriaxone, Iron, Iron Bisglycinate, Calcitriol, and Calcium Alpha-Ketoglutarate.
What should you not take with Calcium?
Calcium is flagged against 3 substances in the database, including Ceftriaxone, Iron, and Iron Bisglycinate. Review these with a clinician before combining, especially alongside prescription medications.
What works well with Calcium?
Calcium pairs synergistically with Betaine HCL, Black Cohosh, Boron, Carbamazepine, and Cinacalcet in the NutriStack database. Synergy still depends on dose and timing; open any pair for the detail.
Can you take Calcium with Ceftriaxone?
NutriStack classifies the Calcium and Ceftriaxone pairing as contraindicated: Ceftriaxone and calcium-containing IV fluids can form insoluble ceftriaxone-calcium precipitates in lung and kidney tissue, with fatal cases reported in neonates. The... Do not infuse IV ceftriaxone with calcium-containing IV solutions, especially in neonates. Oral calcium supplements are generally acceptable but...
Check your whole stack
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