Supplement Combinations to Avoid (and How to Space Them)
These are the pairs our interaction rules currently flag. “Avoid together” means the pair needs a real strategy — different timing, adjusted doses, or a clinician's input — not that either supplement is bad on its own. Every entry links to a full pair guide with timing advice and upper limits.
Pairs to avoid taking at the same moment
- Iron + Zinc
Iron and zinc compete for absorption.
Pairs that compete — split them across meals
- Calcium + Iron
Calcium may interfere with iron absorption when taken together.
- Calcium + Zinc
High doses of calcium may reduce zinc absorption.
- Zinc + Copper
High zinc intake can reduce copper absorption.
Frequently asked questions
What supplements should not be taken together?
The most common clashes are mineral pairs that compete for absorption — for example iron with zinc, or calcium with iron. Each pair has a spacing strategy; open any pair above for its full timing guide and upper limits.
How far apart should I take competing supplements?
For mineral absorption competition, splitting the two doses into different meals is the usual starting strategy. Your exact dose and reason for taking each product can change this, so review your full stack with a clinician when doses are high.
Can I check my whole supplement stack at once?
Yes — NutriAudit lets you photograph your supplement labels and checks every pair, dose overlap, and upper limit in one free scan.
Check your own stack in one free scan
Photograph your supplement labels — NutriAudit checks every pair, duplicate ingredient, and upper limit together.
Open the free interaction checkerEducational reference only — not medical advice. Reviewed against FDA DRI and NIH ODS reference points.