Magnesium Interactions Explained: Drugs, Supplements and Safe Spacing (UK Guide)

TL;DR: Most magnesium interactions happen in the gut—magnesium can bind certain medicines and block their absorption. A few interactions are pharmacodynamic (e.g., effects on heart rhythm or blood pressure). In the UK, NHS and NICE advice generally boils down to spacing doses (often 2–4 hours) and monitoring if you take long‑term medicines or have conditions that alter electrolytes. For an all‑round primer on magnesium itself, see our pillar article: Magnesium Supplements: Evidence‑Based Benefits, Best Forms, Safe Dosage Impact on Common Conditions.

At a glance (quick answers)

• Spacing rule of thumb: Don’t take oral magnesium at the same time as other tablets/capsules. Leave ≥2 hours either side for most medicines; ≥4 hours for thyroid hormone. This general rule appears in UK professional references because magnesium salts can impair absorption of other drugs. Key source: British National Formulary (BNF). [1]
  This simple rule will prevent the vast majority of magnesium interactions and magnesium interaction with medications.
• Big hitters (separate doses):
  — Antibiotics: tetracyclines fluoroquinolones (e.g., doxycycline, ciprofloxacin) 2–3 hours before or 4–6 hours after magnesium. [3] [4]
  — Thyroid: levothyroxine and magnesium need ≥4 hours apart. [2]
  — Bone drugs: alendronate (bisphosphonates) first thing, empty stomach, and avoid minerals that morning. [5]
  — Some statins: rosuvastatin exposure can drop ~50% if taken with aluminium/magnesium hydroxide antacids—separate by ≥2 hours (magnesium and statins). [6] [7]
• Heart rhythm mood medicines: The key risk with magnesium and citalopram interaction is QT prolongation when magnesium is low; PPIs and some diuretics can cause hypomagnesaemia—correct levels and monitor if you’re on citalopram/escitalopram. [8] [9] [10]
  For magnesium and tamoxifen interaction, the same “electrolytes QT” logic applies—keep Mg/K normal and avoid stacking QT‑prolonging drugs. [17] [18] [19]
• Blood thinners: For magnesium and warfarin, there’s no consistent evidence of a clinically important effect from typical magnesium supplements. A magnesium trisilicate antacid reduced warfarin absorption in vitro—so if you use antacid‑type magnesium, separate by ≥2 hours and monitor INR when starting/stopping. [21] [20]
• Blood pressure meds: Magnesium can modestly lower BP (≈2–4 mmHg on average), so watch for additive effects with antihypertensives (magnesium and blood pressure medicine). [22] [23] NICE sets the standard of care for hypertension in England & Wales. [24]

Bookmark for later: timing tips also feature in our pieces on Best Time to Take Magnesium (UK Guide) and Fibre, Coffee, Alcohol and Magnesium: What Reduces Its Absorption? coming soon — handy support reads when planning your routine.

Table of contents

1. Why interactions happen (and how to dodge them)
   1.1 Chelation and gastric pH—the two big mechanisms
   1.2 The UK context: NHS, NICE and BNF advice
2. Safe‑spacing grid (what to separate and for how long)
3. Condition‑by‑condition deep dive
   3.1 Levothyroxine and magnesium
   3.2 Antibiotics (tetracyclines & quinolones)
   3.3 Bisphosphonates for bones
   3.4 Magnesium and statins
   3.5 Heart rhythm & mental health: magnesium and citalopram interaction
   3.6 Breast cancer therapy: magnesium and tamoxifen interaction
   3.7 Anticoagulation: magnesium and warfarin
   3.8 Hypertension & magnesium and blood pressure medicine
4. PPIs, diuretics and low magnesium—when your other meds drain Mg
5. Forms & practicalities (citrate vs glycinate, cramps, sleep)
6. UK‑specific pointers (NHS, NIHR, community pharmacy)
7. FAQs (long‑tail)
8. References

1) Why interactions happen (and how to dodge them)

1.1 Chelation and gastric pH—the two big mechanisms

Most clinically relevant magnesium interactions are pharmaceutical rather than systemic: magnesium ions bind (chelate) to certain drugs (notably tetracyclines, quinolones, levothyroxine), forming complexes the gut can’t absorb. Separating doses often solves these drugs that interact with magnesium. [1] [3] [4]

A second mechanism is gastric pH: some antacid‑type magnesium salts raise pH and can alter dissolution/absorption of acid‑dependent medicines (e.g., certain statins if taken as aluminium/magnesium hydroxide antacids at the same time). [6] [7] The BNF’s general warning—do not co‑administer oral magnesium with other meds; separate by ~2 hours—is a helpful catch‑all to avoid magnesium interaction with medications. [1]

Key takeaway: If you remember one rule for drug interaction with magnesium, it’s “don’t swallow them together”. Most issues vanish with smart spacing. [1]

1.2 The UK context: NHS, NICE and BNF guidance

• The BNF (via NICE) carries practical interaction notes for magnesium and for specific drugs. [1]
• NHS medicine pages (e.g., for levothyroxine, doxycycline, ciprofloxacin, alendronic acid) give plain‑English spacing rules patients can follow. [2] [3] [4] [5]
• Specialist Pharmacy Service (SPS) and national Drug Safety Updates (MHRA) highlight risks such as QT prolongation (citalopram/escitalopram) and hypomagnesaemia with long‑term PPI use. These matter for interpreting magnesium interactions with cardiac and mental‑health drugs. [8] [9] [10] [11]

For foundational knowledge on forms, dosing and who might benefit, circle back to our pillar: Magnesium Supplements: Evidence‑Based Benefits, Best Forms, Safe Dosage & Impact on Common Conditions.

2) Safe‑spacing grid (what to separate and for how long)

Bottom line: This single table prevents most magnesium interactions, reduces risk of any magnesium interaction with medications, and keeps you clear of the common drugs that interact with magnesium.

Medicine (examples)	What can happen with magnesium	How long to space	UK source(s)
Thyroid: levothyroxine	Chelation ↓ absorption (levothyroxine and magnesium)	≥4 h	[2]
Tetracyclines (e.g., doxycycline)	Chelation ↓ antibiotic absorption	2–3 h before or 4–6 h after	[3]
Fluoroquinolones (e.g., ciprofloxacin)	Chelation ↓ antibiotic absorption	2–3 h before or 4–6 h after	[4]
Bisphosphonates (alendronate)	Minerals block uptake	Take alendronate alone, empty stomach; avoid minerals that morning	[5]
Statins (esp. rosuvastatin)	Antacids with aluminium/magnesium hydroxide ↓ exposure ~50% (magnesium and statins)	≥2 h between antacid and statin	[6] [7]
Warfarin	No consistent interaction; magnesium trisilicate antacid may ↓ absorption in vitro (magnesium and warfarin)	≥2 h (if using antacid‑type magnesium) + monitor INR when changing	[21] [20]
Citalopram/escitalopram	Main risk is low Mg → QT prolongation (magnesium and citalopram interaction)	Not a spacing issue; check/correct Mg, especially with PPIs/diuretics	[8] [9] [10]
Tamoxifen	QT risk accentuated by low Mg; limited direct absorption data (magnesium and tamoxifen interaction)	Not a spacing issue; keep Mg normal; separate if using antacid‑type magnesium	[17] [18] [19]

Did you know? A few drugs that interact with magnesium do so beneficially—for example, magnesium can modestly lower blood pressure, so if you’re on antihypertensives (magnesium and blood pressure medicine), watch for a small additive effect. [22] [23] [24]

3) Condition‑by‑condition deep dive

3.1 Levothyroxine and magnesium — the 4‑hour rule

Magnesium (and calcium/iron) binds levothyroxine and can undercut absorption, leading to erratic thyroid control. NHS/BNF‑aligned advice: take levothyroxine on an empty stomach first thing, then leave at least 4 hours before magnesium. This single step resolves most levothyroxine and magnesium problems. [2]
Key takeaway: Always separate—this is the archetypal drug interaction with magnesium to avoid. [2]

To fine‑tune your magnesium form for comfort/absorption later in the day, our explainer Magnesium Citrate vs Glycinate vs L‑Threonate: Benefits, Absorption & How to Choose the Best Form walks through pros/cons.

3.2 Antibiotics — tetracyclines & quinolones

For doxycycline and ciprofloxacin, magnesium forms insoluble complexes that your gut won’t absorb. NHS guidance is explicit: swallow these antibiotics well away from magnesium (and other minerals). Follow the 2–3 h before or 4–6 h after rule. This is a classic case of magnesium interaction with medications solved by smart scheduling. [3] [4]
Key takeaway: Treat tetracyclines/quinolones as high‑risk chelators among drugs that interact with magnesium. [3] [4]

If you’re using magnesium for migraine prevention while on a short antibiotic course, see Magnesium for Migraines UK: A Guide to Using Magnesium Citrate for Relief for timing tips around acute/short‑term medicines.

3.3 Bisphosphonates (e.g., alendronic acid)

Alendronate needs near‑perfect conditions to absorb: empty stomach, full glass of water, remain upright 30 minutes, and no minerals (magnesium/calcium/iron) that morning. NHS instructions are crystal clear. [5]
Key takeaway: With bones, it’s not magnesium interactions per se—it’s that bisphosphonates are ultra‑fussy. Keep all supplements for later in the day. [5]

3.4 Magnesium and statins — mostly about antacids

Where magnesium and statins cross is via antacid co‑administration. The UK SmPC for rosuvastatin (Crestor) shows a ~50% drop in exposure when taken with aluminium/magnesium hydroxide antacids; taking the antacid 2 hours after rosuvastatin reduces the effect. [6] The PK literature echoes this interaction. [7]
Key takeaway: If you use an antacid‑type magnesium, separate from statins by ≥2 hours. That one tweak defuses this magnesium interaction with medications. [6] [7]

3.5 Heart rhythm & mood: Magnesium and citalopram interaction

The phrase magnesium and citalopram interaction can be misleading—there’s no routine chelation issue. The real risk is electrophysiology: citalopram/escitalopram can prolong the QT interval, and low magnesium (often from long‑term PPI use or certain diuretics) worsens that risk. The MHRA Drug Safety Update for citalopram/escitalopram stresses caution, ECG when indicated, and correction of electrolytes. [8] UK guidance on drug‑induced QT prolongation reiterates checking and correcting low Mg/K. [9] Meanwhile, the MHRA has also warned that PPIs can cause significant hypomagnesaemia, sometimes after months to years of therapy; levels usually normalise after stopping the PPI (sometimes not with supplementation alone). [10] [11]
What to do:

• If you’re on citalopram (or another QT‑prolonging drug), measure and correct magnesium if symptomatic or if you’re on a long‑term PPI/diuretic. [8] [9] [10]
• This is a monitoring issue, not a spacing problem—still, spacing helps avoid other magnesium interactions.
• Ask your GP/pharmacist (NHS) if unsure; consider NIHR Evidence summaries for accessible, UK‑context research digests.

Key takeaway: The safest way to think about the magnesium and citalopram interaction is “perfect the magnesium level to protect the heart”, not “don’t take them together”. [8] [9] [10]

3.6 Oncology: Magnesium and tamoxifen interaction

Evidence points to QT‑interval considerations here too. Tamoxifen itself has been associated with QT changes, and a 2019 analysis found higher QTc when tamoxifen was combined with specific SSRIs (paroxetine, escitalopram, citalopram). [17] General cardio‑guidance is to correct electrolytes (including magnesium) when QT risk is present. [18] The MHRA emphasises tamoxifen’s prodrug metabolism and the impact of interacting medicines; while direct chelation with magnesium isn’t a feature, maintaining normal magnesium is part of good QT hygiene. [19]
Key takeaway: Treat magnesium and tamoxifen interaction like citalopram—keep Mg normal, avoid stacking QT risks, and if you use antacid‑type magnesium, separate doses to be safe. [17] [18] [19]

3.7 Anticoagulation: Magnesium and warfarin

For routine supplements, magnesium and warfarin is not a strongly established clinical interaction. The UK NHS warns that many medicines and supplements can affect warfarin and recommends checking with a pharmacist/clinician before starting anything new. [21] A professional monograph notes an in vitro study where magnesium trisilicate antacid reduced warfarin absorption ~19% across a physiological membrane—clinical relevance uncertain. [20]
Practical approach:

• If you’re stable on warfarin and add antacid‑type magnesium, space by ≥2 hours and check INR after a few days.
• Diarrhoea from high‑dose magnesium can also affect INR indirectly—report any changes to your anticoagulation clinic.

Key takeaway: Respect the combo, but don’t fear magnesium and warfarin—monitor and separate. [21] [20]

3.8 Blood pressure & heart meds: Magnesium and blood pressure medicine

Meta‑analyses (including Hypertension 2016 and a 2017 RCT meta‑analysis) show magnesium supplementation produces modest average BP reductions (roughly 2–4 mmHg), with larger effects in those with metabolic disease or higher baseline BP. [22] [23] UK care follows NICE NG136, which sets targets and the step‑wise drug approach. [24]
Implication: With magnesium and blood pressure medicine, it’s about additive effects—use common sense:

• If you add magnesium (especially ≥300–400 mg elemental/day), check home BP for a couple of weeks. [22] [23]
• Report symptoms of low BP (dizziness on standing), and coordinate with your GP.
• Our deeper dive Magnesium and Blood Pressure (BP): Does Magnesium Help with High Blood Pressure, Palpitations, and Atrial Fibrillation? expands on the evidence.

Key takeaway: The interaction here is usually beneficial synergy, but monitoring ensures magnesium interactions don’t translate into unwanted hypotension with magnesium and blood pressure medicine. [22] [23] [24]

4) PPIs, diuretics and low magnesium—when your other meds drain Mg

Two common medicine classes that lower magnesium:

• PPIs (omeprazole, lansoprazole, etc.): The MHRA’s Drug Safety Update flags severe hypomagnesaemia with long‑term use (sometimes >1 year, occasionally <3 months). In some reports, Mg levels did not correct until the PPI was stopped. [10] [11]
• Diuretics: Thiazides are consistently associated with lower serum magnesium and an increased risk of hypomagnesaemia; loop diuretics may contribute, with variability across studies. [25] [27]

If you’re on a PPI and/or diuretic and a QT‑sensitive medicine (citalopram, tamoxifen), you’ve stacked risk. Correct by checking Mg, treating low levels, and—if appropriate—reviewing PPI need and dose with your clinician. [10] [11] [25] [27]

Resource: NHS hospital and ICB guidance sheets outline hypomagnesaemia symptoms, causes and replacement. [26] [28]

For symptom awareness and diet tips, see Magnesium Deficiency Symptoms: How to Recognise and Address Them (UK) and Top 10 Foods High in Magnesium – Natural Alternatives to Supplements.

5) Forms & practicalities (when and what to take)

• When to take: Many people find magnesium calmer in the evening; others split doses. The main goal is to avoid overlap with drugs that interact with magnesium and to keep magnesium interaction with medications to a minimum. See Best Time to Take Magnesium: With Food or Empty Stomach, Morning or Night? (UK Guide).
• Which form: Citrate is well‑absorbed but can loosen stools; glycinate is gentler; oxide has more laxative effect. If cramps keep you awake, our Magnesium Citrate for Muscle Cramps & Night Leg Cramps: Evidence and Dosage (UK Guide) summarises the data.
• One‑a‑day idea: If you need a low‑to‑moderate daily amount and want simple spacing, consider magnesium citrate 150 mg in the evening: Capsure Magnesium Citrate 150 mg (120 capsules).

6) UK‑specific pointers (NHS, NIHR, community pharmacy)

• Community pharmacists are trained to screen for magnesium interactions at the counter—they can help you place magnesium around magnesium and blood pressure medicine or levothyroxine and magnesium.
• NICE NG136 sets BP targets and therapy steps; if magnesium brings your pressure down a notch, a clinician might de‑intensify antihypertensives accordingly. [24]
• NIHR Evidence publishes accessible summaries of UK‑relevant research; keep an eye there for future updates on magnesium’s clinical roles. (NIHR Evidence portal).

And for the full magnesium “what, why, how much” story, don’t miss our pillar: Magnesium Supplements: Evidence‑Based Benefits, Best Forms, Safe Dosage & Impact on Common Conditions.

7) FAQs (long‑tail)

Q: Is there a straightforward list of drugs that interact with magnesium I can memorise?
A: Think in families: levothyroxine, tetracyclines/quinolones, bisphosphonates, certain statins (if using antacid‑type magnesium), and warfarin (only caution with antacid‑type magnesium). Everything else is usually fine when spaced—reducing the chance of any drug interaction with magnesium. [1] [2] [3] [4] [5] [6] [7] [21] [20]

Q: What about magnesium and citalopram interaction—should I avoid magnesium?
A: No, the focus is on avoiding low magnesium (which increases QT risk). If you’re on a PPI or diuretic, ask for magnesium to be checked and corrected; there’s no routine need to space citalopram from magnesium. [8] [9] [10] [11]

Q: How strict is the 4‑hour rule for levothyroxine and magnesium?
A: Very. Absorption is easily compromised; the NHS advises ≥4 hours apart. If in doubt, take levothyroxine first thing, magnesium later that day. [2]

Q: Any concerns with magnesium and tamoxifen interaction during long treatment courses?
A: Prioritise electrolyte normalisation (magnesium, potassium) and avoid stacking QT‑prolonging drugs. Separate if using antacid‑type magnesium purely as a belt‑and‑braces approach. [17] [18] [19]

Q: Can magnesium replace blood pressure medicine?
A: No. While supplementation may shave 2–4 mmHg, NICE‑directed care treats hypertension with lifestyle plus medicines as needed; think of magnesium as a supporting act. (Magnesium and blood pressure medicine can work in tandem—monitor at home.) [22] [23] [24]

Q: Any special notes on magnesium and statins beyond rosuvastatin?
A: The clearest evidence is rosuvastatin + aluminium/magnesium hydroxide antacids; spacing remedies the drop in exposure. Check individual SmPCs and separate to avoid magnesium interactions. [6] [7]

Q: Ultimately, how do I avoid any magnesium interaction with medications?
A: Space by 2 hours (4 hours for levothyroxine), keep magnesium levels normal (especially with citalopram/tamoxifen), and involve your pharmacist/GP when starting or stopping supplements.

References

1. National Institute for Health and Care Excellence (NICE). Magnesium: interactions – BNF [Internet]. London: NICE; [cited 2025 Aug 15]. Available from: https://bnf.nice.org.uk/interactions/magnesium/
2. National Institute for Health and Care Excellence (NICE). Levothyroxine: interactions – BNF [Internet]. London: NICE; [cited 2025 Aug 15]. Available from: https://bnf.nice.org.uk/interaction/levothyroxine/
3. NHS. Doxycycline: taking with other medicines and herbal supplements [Internet]. London: NHS; 2024–2025 [cited 2025 Aug 15]. Available from: https://www.nhs.uk/medicines/doxycycline/taking-doxycycline-with-other-medicines-and-herbal-supplements/
4. NHS. Ciprofloxacin: taking with other medicines and herbal supplements [Internet]. London: NHS; 2024–2025 [cited 2025 Aug 15]. Available from: https://www.nhs.uk/medicines/ciprofloxacin/taking-ciprofloxacin-with-other-medicines-and-herbal-supplements/
5. NHS. Alendronic acid: how and when to take it [Internet]. London: NHS; 2024–2025 [cited 2025 Aug 15]. Available from: https://www.nhs.uk/medicines/alendronic-acid/how-and-when-to-take-alendronic-acid/
6. AstraZeneca UK Ltd. Crestor 5 mg, 10 mg, 20 mg and 40 mg film-coated tablets (rosuvastatin): summary of product characteristics [Internet]. electronic Medicines Compendium (emc); revised 2024 [cited 2025 Aug 15]. Available from: https://www.medicines.org.uk/emc/product/8589/smpc
7. Mazzu AL, Lasseter KC, Shamblen EC, Agarwal V, Lettieri J, Miller R. Effect of aluminium and magnesium hydroxide on the pharmacokinetics of rosuvastatin in healthy adult male volunteers. Clin Ther. 2009;31(10):2212–24 [Internet]. [cited 2025 Aug 15]. Available from: https://pubmed.ncbi.nlm.nih.gov/19808137/
8. Medicines and Healthcare products Regulatory Agency (MHRA). Citalopram and escitalopram: QT interval prolongation—new maximum daily dose restrictions [Internet]. Drug Safety Update; 2011–2014 [cited 2025 Aug 15]. Available from: https://www.gov.uk/drug-safety-update/citalopram-and-escitalopram-qt-interval-prolongation-new-maximum-daily-dose-restrictions
9. AAA Medicines. Guideline on drug-induced QT prolongation [Internet]. UK formulary services; updated 2024 [cited 2025 Aug 15]. Available from: https://aaamedicines.org.uk/media/m13hdonk/guideline-qtc-prolongation.pdf
10. Medicines and Healthcare products Regulatory Agency (MHRA). Proton pump inhibitors in long-term use: reports of hypomagnesaemia [Internet]. Drug Safety Update; 2012/2014 [cited 2025 Aug 15]. Available from: https://www.gov.uk/drug-safety-update/proton-pump-inhibitors-in-long-term-use-reports-of-hypomagnesaemia
11. Begley J, Smellie WSA. Proton pump inhibitor-associated hypomagnesaemia. Br J Clin Pharmacol. 2016;81(4):753–8 [Internet]. [cited 2025 Aug 15]. doi:10.1111/bcp.12846
12. NHS Tees, Esk and Wear Valleys. Citalopram and escitalopram in adults: prescribing guidance [Internet]. 2024 [cited 2025 Aug 15]. Available from: https://www.tewv.nhs.uk/wp-content/uploads/2021/11/Citalopram-escitalopram-QT-prolongation.pdf
13. North Tees and Hartlepool NHS Foundation Trust. Levothyroxine: food and drink interactions (TSH monitoring advice) [Internet]. 2021–2024 [cited 2025 Aug 15]. Available from: https://www.nth.nhs.uk/resources/levothyroxine-food-and-drink-interactions/
14. Scottish Antimicrobial Prescribing Group. Oral tetracyclines and fluoroquinolones—interactions with cations (audit toolkit) [Internet]. 2017–2024 [cited 2025 Aug 15]. Available from: https://www.sapg.scot/guidance-qi-tools/antimicrobials-and-oral-cation-interactions/
15. Zhang X, Li Y, Del Gobbo LC, Rosanoff A, Wang J, Zhang W, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomised double-blind placebo-controlled trials. Hypertension. 2016;68(2):324–33 [Internet]. [cited 2025 Aug 15]. doi:10.1161/HYPERTENSIONAHA.116.07664
16. Dibaba DT, Xun P, He K. The effect of magnesium supplementation on blood pressure in individuals with insulin resistance, prediabetes, or noncommunicable chronic diseases: a meta-analysis of randomised controlled trials. Am J Clin Nutr. 2017;106(3):921–9 [Internet]. [cited 2025 Aug 15]. doi:10.3945/ajcn.117.155291
17. Hussaarts KGAM, Berger FA, Binkhorst L, Oomen-de Hoop E, van Leeuwen RWF, van Alphen RJ, et al. The risk of QTc-interval prolongation in breast cancer patients treated with tamoxifen in combination with serotonin reuptake inhibitors. Pharm Res. 2019;37(1):7 [Internet]. [cited 2025 Aug 15]. doi:10.1007/s11095-019-2746-9
18. Porta-Sánchez A, et al. Incidence, diagnosis, and management of QT prolongation induced by cancer therapies. J Am Heart Assoc. 2017;6(12):e007724 [Internet]. [cited 2025 Aug 15]. doi:10.1161/JAHA.117.007724
19. Medicines and Healthcare products Regulatory Agency (MHRA). Tamoxifen for breast cancer—CYP2D6 metabolism and clinical response [Internet]. Drug Safety Update; 2014 [cited 2025 Aug 15]. Available from: https://www.gov.uk/drug-safety-update/tamoxifen-for-breast-cancer
20. Drugs.com Professional. Drug interaction report: warfarin and magnesium trisilicate (absorption study) [Internet]. 2023–2025 [cited 2025 Aug 15]. Available from: https://www.drugs.com/interactions-check.php?drug_list=3392-0%2C2311-0&professional=1
21. NHS. Taking warfarin with other medicines and herbal supplements [Internet]. London: NHS; 2022–2025 [cited 2025 Aug 15]. Available from: https://www.nhs.uk/medicines/warfarin/taking-warfarin-with-other-medicines-and-herbal-supplements/
22. Zhang X, Li Y, Del Gobbo LC, Rosanoff A, Wang J, Zhang W, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomised double-blind placebo-controlled trials. Hypertension. 2016;68(2):324–33 [Internet]. [cited 2025 Aug 15]. doi:10.1161/HYPERTENSIONAHA.116.07664
23. Dibaba DT, Xun P, He K. The effect of magnesium supplementation on blood pressure in individuals with insulin resistance, prediabetes, or noncommunicable chronic diseases: a meta-analysis of randomised controlled trials. Am J Clin Nutr. 2017;106(3):921–9 [Internet]. [cited 2025 Aug 15]. doi:10.3945/ajcn.117.155291
24. National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management (NG136) [Internet]. London: NICE; 2019 [updated 2024 Nov 27; cited 2025 Aug 15]. Available from: https://www.nice.org.uk/guidance/ng136
25. Kieboom BCT, et al. Thiazide but not loop diuretics associated with hypomagnesaemia in the general population. Pharmacoepidemiol Drug Saf. 2018;27(11):1166–73 [Internet]. [cited 2025 Aug 15]. doi:10.1002/pds.4636
26. Royal United Hospitals Bath NHS Foundation Trust. Hypomagnesaemia – a guide for GPs [Internet]. 2024 Jun 7 [cited 2025 Aug 15]. Available from: https://www.ruh.nhs.uk/pathology/documents/clinical_guidelines/PATH-021_Hypomagnesaemia_Guideline.pdf
27. Adomako EA, et al. Magnesium disorders: core curriculum 2024. Am J Kidney Dis. 2024;83(6):822–40 [Internet]. [cited 2025 Aug 15]. doi:10.1053/j.ajkd.2023.10.017

0

Final practical checklist

• Use the 2‑hour rule (and 4‑hour for levothyroxine and magnesium).
• Keep an eye on magnesium and blood pressure medicine if you’re adding Mg—check home BP. [22] [23] [24]
• For magnesium and statins, separate antacid‑type magnesium. [6] [7]
• For magnesium and citalopram interaction and magnesium and tamoxifen interaction, think QT + electrolytes—measure & correct Mg, especially if you take a PPI or diuretic. [8] [9] [10] [11] [17] [18] [19]
• With magnesium and warfarin, separate by 2 hours if using antacid‑type salts and check INR after changes. [21] [20]