What should not be taken together with magnesium?

Taking magnesium preparations

Magnesium is one of the micronutrients and is frequently used as a food supplement. Various processes take place in the body during the absorption of active ingredients and nutrients. When taken at the same time as certain medicines or high-dose mineral preparations, the absorption of individual active ingredients or nutrients can be affected. That is why, with some combinations, a time gap is important.

The central question of this article is therefore: what should not be taken together with magnesium? Here, “not together” usually does not mean that a combination is fundamentally prohibited. The reason for necessary dosing intervals depends on the particular combination. What matters is the specific active ingredient, the respective magnesium preparation and the dosing intervals stated in the package leaflet. A normal diet and magnesium from food are deliberately not the focus of this article.

Taking magnesium: where is particular caution advisable?

When taking magnesium together with medicines, particular attention is sensible. According to the Hesse State Chamber of Pharmacists (Landesapothekerkammer Hessen), calcium, magnesium, zinc and iron can reduce the absorption of various antibiotics and thyroid preparations. For people who regularly take medicines, the information in the package leaflet is therefore particularly important. In case of uncertainty or health-related questions, use should be coordinated with the doctor’s practice or the pharmacy.^1,6

• Antibiotics – in particular tetracyclines and fluoroquinolones (gyrase inhibitors): these should not be taken at the same time as magnesium. For Magnesium 100 mg JENAPHARM, an interval of 2 to 3 hours is stated for tetracyclines. One example of differing requirements is ciprofloxacin: it should be taken 1 to 2 hours before or at least 4 hours after magnesium-containing preparations. The package leaflet of the specific antibiotic is always decisive.^2,3
• Thyroid preparations: here too, minerals can affect absorption. The Hesse State Chamber of Pharmacists recommends the largest possible interval – but at least two hours – between calcium, magnesium, zinc or iron and various thyroid preparations. The information for the respective medicine takes precedence.¹
• Bisphosphonates: with individual bisphosphonates, simultaneous intake with magnesium should likewise be avoided. The patient information leaflet for Risedron-HEXAL notes that calcium, magnesium, aluminium and iron can reduce the effect when taken at the same time. These preparations should be taken no earlier than 30 minutes after risedronate.⁴

Taking magnesium together with iron, zinc, calcium and other minerals

Not only medicines, but also higher-dose mineral preparations can influence one another’s absorption when taken at the same time. The German consumer advice centre (Verbraucherzentrale) names magnesium, calcium, iron and zinc in particular here. The amount of the individual minerals and the specific product composition can play a role. Anyone using several micronutrients as supplements should therefore compare the product information and not automatically take all preparations at the same time.⁵ How magnesium and potassium interact is explained in the article Magnesium and potassium – why do we need them?.

• Iron and magnesium: when higher-dose preparations are taken at the same time, iron and magnesium can affect one another’s absorption in the intestine. The patient information leaflet for Magnesium 100 mg JENAPHARM notes that the absorption of iron may be impaired. A time separation can therefore be sensible; the specific interval depends on the preparations used.²
• Zinc and magnesium: when higher-dose preparations are taken at the same time, zinc and magnesium can hinder one another’s absorption. However, the consumer source reviewed does not give a general requirement for a blanket interval of exactly two hours. The manufacturer’s information for the respective product therefore applies.⁵
• Calcium and magnesium: higher-dose calcium taken at the same time can also affect magnesium absorption. A generally applicable intake ratio of 2:1 cannot be derived from the reviewed sources. What matters is the dosage of the specific preparation and the respective intake instructions.⁵

Anyone combining several food supplements should also check whether minerals or vitamins are duplicated across different products. With combination preparations, it is also worth looking at which magnesium compounds and other ingredients are contained – magnesium stearate should not be confused with a magnesium compound for magnesium intake (more on this in the article Magnesium stearate: a bad reputation without cause?). It is precisely here that not only the individual magnesium intake is relevant, but the interplay of all the micronutrients contained and any medicines.^5,6

Combination preparations and several supplements: what to consider when taking them?

With combination preparations and the parallel use of several supplements, it is worth looking at the ingredients list and the intake instructions. The consumer advice centre points out that combination products can contain further vitamins or minerals and that interactions with nutrients or medicines are possible.^5,6

Anyone who takes medicines should therefore not consider just a single magnesium preparation, but state all food supplements that are used regularly. In this way, the doctor’s practice or pharmacy can check whether certain preparations should be taken at separate times. With several products, the time of day of intake can also play a role – the respective intake instructions remain decisive.

Practical tips: what should be taken at separate times?

For taking magnesium, the following practical tips can be noted on the basis of the reviewed sources. For every product, the package leaflet or the specific product information is decisive:

Conclusion

What should not be taken together with magnesium? Dosing intervals can be important particularly with certain antibiotics, thyroid preparations and individual bisphosphonates. Higher-dose preparations containing iron, zinc or calcium can also affect the absorption of magnesium or other minerals. In the case of regular medicine use or uncertainty, taking magnesium should be coordinated with the doctor’s practice or the pharmacy. What is decisive is not a blanket list of prohibitions, but the specific combination and the dosing interval stated for the respective medicine or food supplement.

Frequently asked questions about taking magnesium

Can you take magnesium together with antibiotics?

Certain antibiotics should not be taken at the same time as magnesium – these include, for example, tetracyclines and some fluoroquinolones. Magnesium can form compounds with these active ingredients and thereby affect their absorption. Which dosing interval is required depends on the particular active ingredient and should be taken from the package leaflet or coordinated with a doctor or pharmacist.

Can you take magnesium together with L-thyroxine?

Magnesium-containing preparations should not be taken at the same time as levothyroxine, as minerals can affect the absorption of the thyroid hormone. There should therefore be a time gap between the two preparations. The specific intake instructions for the respective medicine should always be observed.

Does an interval of two hours always apply for magnesium and medicines?

No. The necessary interval depends on the particular medicine. For some magnesium medicines, an interval of two to three hours is recommended. For individual active ingredients, however, other requirements apply: ciprofloxacin, for example, should be taken one to two hours before or at least four hours after magnesium-containing preparations. That is why the information in the respective package leaflet is decisive.

What should be considered with magnesium and bisphosphonates?

With certain bisphosphonates used to treat osteoporosis, simultaneous intake with minerals can also be problematic. Poorly soluble compounds can form, as a result of which the active substance is absorbed less well. Magnesium preparations should therefore not be taken at the same time; the specific dosing interval depends on the respective medicine.

What should be considered with a magnesium deficiency and simultaneous medicine use?

Anyone who takes a magnesium preparation for supplementary supply due to a diagnosed magnesium deficiency and uses medicines at the same time should pay attention to possible interactions and dosing intervals. Certain medicines, including some antibiotics or thyroid medicines, can be affected in their absorption when magnesium is taken at the same time. There is no generally applicable rule for the dosing interval. The specific intake should therefore be coordinated with the doctor’s practice or pharmacy.

Sources

1. Hesse State Chamber of Pharmacists / Landesapothekerkammer Hessen (06/05/2024): food supplements can interact with medicines – Calcium, magnesium, zinc and iron can reduce the absorption of various antibiotics and thyroid preparations; at least two hours’ interval.
2. PatientenInfo-Service / mibe GmbH: patient information leaflet Magnesium 100 mg JENAPHARM (as of January 2023) – Notes on dosing intervals for tetracyclines (2 to 3 hours) and on the possible impairment of iron absorption.
3. Fachinfo-Service: Ciprobay 250 mg, film-coated tablets (as of January 2026) – Ciprofloxacin should be taken 1 to 2 hours before or at least 4 hours after magnesium-containing preparations.
4. PatientenInfo-Service / HEXAL AG: Risedron-HEXAL 35 mg once weekly (as of September 2025) – Calcium, magnesium, aluminium and iron can reduce the effect; take no earlier than 30 minutes after risedronate.
5. Verbraucherzentrale (German consumer advice centre): Magnesium – what to consider? – Notes on how higher-dose minerals (magnesium, calcium, iron, zinc) can influence one another’s absorption.
6. Verbraucherzentrale: using food supplements correctly – General notes on combination products and possible interactions with nutrients or medicines.