Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.
How long to take it
Temporary for most, ongoing after menopause or with osteoporosis treatment.
Who it's actually for
People with genuinely low dairy and leafy green intake, and post-menopausal women.
Safe upper limit
Verified2,500 mg per day (2,000 mg over age 50)
Excess raises kidney stone risk and, in some studies, arterial calcification. Supplemental calcium behaves differently from dietary calcium.
2,500 mg/day for ages 19–50; 2,000 mg/day for ages 51+.
Interactions to know about
- Thyroid medication — Levothyroxine, carbimazole, methimazole
- Antibiotics — Especially tetracyclines and quinolones
- Bone medication — Alendronate, risedronate
- Acid blockers — Omeprazole, lansoprazole, famotidine
Other supplements:
Run your full list through the interaction check.
Practical notes
- Split into doses of 500 mg or less — absorption caps out.
- Carbonate needs food and stomach acid; citrate does not.
- Pair with vitamin D and K2 rather than taking it alone.