A complete safety, timing, and dosage guide for combining Magnesium (Citrate, Glycinate, Oxide, Threonate) with Fish Oil (Omega-3: EPA / DHA) — including how the two supplements interact, the best time of day to take each, and which populations should be careful.
Yes, you can safely take magnesium and fish oil together. They do not interact negatively, and many people combine them daily for heart, muscle, and overall wellness support.
Magnesium and fish oil together are safe for healthy adults. These two supplements use completely different absorption pathways, so there is no competition or risk of reduced effectiveness. You do not need to space them apart or worry about side effects beyond each supplement's normal tolerance.
Magnesium is a positively charged mineral that your body absorbs mainly in the small intestine through active transport via TRPM6/7 channels and passive paracellular diffusion. Omega-3 fatty acids from fish oil, by contrast, are fat-soluble molecules that get incorporated into mixed micelles, absorbed into enterocytes, packaged into chylomicrons, and carried through the lymphatic system before entering the bloodstream. Because these two pathways are entirely separate, there is no receptor competition or shared transporter that could cause one to block the other. Magnesium does not alter the enzymes (lipases) that release EPA and DHA from triglycerides, and fish oil does not change magnesium's renal reabsorption or intestinal handling. The only theoretical point of contact is that magnesium oxide, because it is an antacid, can raise stomach pH slightly, but this effect is too small to meaningfully change omega-3 digestion or absorption. In short, the combination is biologically neutral and safe.
For most people, the easiest approach is to take both magnesium and fish oil with dinner, since fat in the meal helps omega-3 absorption and magnesium is often better tolerated later in the day. A typical dose is 200 to 400 milligrams of elemental magnesium in a well-absorbed form like glycinate or citrate, alongside 1 to 2 grams of fish oil providing at least 500 milligrams of combined EPA and DHA. There is no need to separate them by any specific number of minutes; taking them together is fine. If you miss a dose, just take it with your next meal, but do not double up. If you are also taking thyroid medication or certain antibiotics, separate magnesium from those medications by at least two hours, but there is no need to separate magnesium from fish oil.
The specific form of magnesium matters more for magnesium absorption than for its interaction with fish oil. Magnesium oxide is the least bioavailable form and often causes loose stools, whereas citrate, glycinate, and threonate are generally better absorbed and better tolerated; this is worth considering if you are taking magnesium for sleep, muscles, or brain health. Fish oil forms also vary — ethyl ester products may be slightly less efficiently absorbed than natural triglyceride forms, and some people get fishy burps with lower-quality oils. Neither form difference affects the safety of combining magnesium with fish oil, so choose the forms that work best for your digestion and goals.
This pair commonly appears in comprehensive cardiovascular wellness stacks, frequently alongside vitamin D and CoQ10. A number of sleep and recovery formulas also combine a modest dose of magnesium glycinate or threonate with a low-dose omega-3 from fish oil.
Yes, you can take magnesium and fish oil at the same time. Your body absorbs them through completely different pathways, so there is no meaningful competition or negative interaction. I often tell my patients to take both with dinner for convenience and better tolerance.
Yes, it is safe to combine magnesium and fish oil every day as long as you stay within standard recommended doses. Most healthy adults can take both long-term without any issues. If you have kidney disease or take a blood thinner, have a quick discussion with your doctor before starting.
You do not need to wait at all. Magnesium and fish oil can be taken at the same time, and there is no required spacing. If you find that one of them upsets your stomach on its own, you can take them at different meals, but that is about personal comfort, not an interaction.
No, they do not compete. Magnesium is a mineral absorbed through specific ion channels and paracellular diffusion in the small intestine, while omega-3 fatty acids are fat-soluble and processed through micelles and lymphatic transport. Their absorption there is no competition between them.
Most people can take them together, but those with chronic kidney disease should avoid magnesium unless a doctor approves it, because the kidneys may not clear it properly. People on blood thinners should discuss fish oil with their prescriber due to the mild bleeding risk at high doses. If you have a fish allergy, consider plant-based omega-3 instead.
I recommend taking both with food. Fish oil is absorbed best when consumed with a meal that contains fat, and it is less likely to cause burping or reflux. Magnesium is generally fine on an empty stomach, but taking it with food can prevent nausea and the laxative effect of forms like oxide.
Reviewed by Caroline M. on April 16, 2026 for accuracy against the sources listed above. This page is educational and is not a substitute for professional medical advice.
The matrix has 86 supplements and 7310 pairwise interactions. Click any cell to see the full breakdown.