Calcium: How Much You Need and How to Take It
Calcium keeps your bones, teeth and muscles working. Sounds basic, but small mistakes — wrong dose, bad timing with meds, or the wrong supplement type — can make it less useful or even risky. Here’s what actually helps you get the benefit without surprises.
Who needs how much
Most adults need about 1,000 mg of calcium a day. Women over 50 and men over 70 usually need around 1,200 mg. You get a lot from dairy, leafy greens, fortified plant milks, canned salmon with bones, and tofu. If you can meet targets with food, that’s usually best — supplements fill the gap when diet falls short.
Choosing and using supplements
Two common forms are calcium carbonate and calcium citrate. Carbonate has more elemental calcium and is cheaper, but it works best with food. Citrate is easier on the stomach and can be taken anytime, including if you have low stomach acid or take acid-blocking meds.
Don’t take more than about 500–600 mg at once. Your body absorbs smaller doses better, so split a 1,000 mg supplement into two doses. Pair calcium with vitamin D — vitamin D improves absorption. A typical daily vitamin D dose many people use is in the 800–1,000 IU range, but check with your doctor for what’s right for you.
Watch the total: add up food plus supplements. Too much calcium long-term can raise the chance of kidney stones or lead to high blood calcium, especially if you have certain conditions.
If you have chronic kidney disease, talk to your nephrologist before starting supplements — the balance of calcium, phosphate and vitamin D changes in kidney disease and needs medical oversight.
Timing matters with other drugs. Here are practical separation times to avoid interactions: keep calcium 2 hours away from iron supplements, take it 2–4 hours apart from tetracycline antibiotics like doxycycline (Vibramycin) and from fluoroquinolones like ciprofloxacin, and allow at least 4 hours between calcium and thyroid pills (levothyroxine). Also mention your doctor if you’re on digoxin — very high blood calcium can worsen digoxin effects.
If you’re taking medications you bought online or reading about on this site — like antibiotics (see our Vibramycin and Augmentin alternatives posts) or heart meds (see our Digoxin guide) — check timing with a pharmacist or the prescriber. Small timing tweaks usually fix absorption problems.
Quick checklist: aim for mostly food sources, split supplemental doses under 500–600 mg each, pick carbonate with meals or citrate anytime, keep calcium away from iron and certain antibiotics, and check with your doctor if you have kidney disease or take prescription meds. Got questions about a specific drug interaction? Look up the medication or ask a pharmacist — it’s worth a two-minute call.
