If you take medication for blood pressure, your prescription may be affecting your magnesium levels. Not all blood pressure drugs do this, but some of the most commonly prescribed ones in the UK do, and the effect can build up quietly over months and years.
This article looks at which medications are involved, what the research says about magnesium’s role in cardiovascular health, and what to consider if you think your levels might be low. It is not a guide to adjusting your medication. Always discuss any supplement changes with your GP or pharmacist first.
Table of Contents
Why magnesium matters for blood pressure
Magnesium plays a structural role in how blood vessels behave. It acts as a natural calcium antagonist, helping smooth muscle in artery walls to relax rather than contract. When magnesium is low, vascular tone increases. Sustained vascular tension is a known driver of elevated blood pressure.
A 2016 meta-analysis published in Hypertension reviewed 34 clinical trials and found that magnesium supplementation was associated with modest reductions in both systolic and diastolic blood pressure (Zhang et al., 2016). The effect sizes were not large enough to position magnesium as a standalone treatment for hypertension, and researchers noted that low baseline magnesium levels appeared to drive the strongest response.
The point is not that magnesium supplements replace medication. It is that magnesium deficiency and blood pressure regulation are connected at a physiological level, which is why depleting medications matter.
Which blood pressure medications deplete magnesium
Different classes of blood pressure medication carry very different levels of risk. The table below summarises the key differences; more detail on each follows.
| Drug class | Examples | Mechanism | Magnesium risk |
|---|---|---|---|
| Thiazide diuretics | Bendroflumethiazide, indapamide | Block the NCC transporter, reducing magnesium reabsorption in the kidney | High (common cause of hypomagnesaemia with long-term use) |
| Loop diuretics | Furosemide, bumetanide | Block the NKCC2 transporter in the loop of Henle | High (more potent than thiazides) |
| ACE inhibitors / ARBs | Lisinopril, ramipril, perindopril, losartan, candesartan | Act on the renin-angiotensin-aldosterone system, not renal magnesium transporters | Low (may be mildly magnesium-sparing) |
| Beta-blockers / calcium channel blockers | Bisoprolol, atenolol, amlodipine, diltiazem | No direct action on magnesium-regulating renal transporters | Low (no direct depletion effect) |
Thiazide diuretics
Thiazide diuretics are among the most widely prescribed blood pressure medications in the UK. Bendroflumethiazide and indapamide are two of the most common. They work by increasing urine output, which reduces fluid volume and lowers pressure on vessel walls.
The same mechanism that flushes excess fluid also increases magnesium excretion through the kidneys. Thiazides block the NCC transporter in the distal convoluted tubule, which reduces the kidney’s ability to reabsorb magnesium before it leaves in urine (Quamme, 1997). The result is a gradual, ongoing loss that worsens with long-term use.
Research consistently identifies thiazide use as a cause of hypomagnesaemia, clinically low magnesium, particularly in older adults (Ryan, 1984; Gröber et al., 2015).
Loop diuretics
Loop diuretics such as furosemide and bumetanide are more potent than thiazides and carry a higher risk of magnesium loss. They block the NKCC2 transporter in the loop of Henle, disrupting a key site of magnesium reabsorption in the kidney.
Loop diuretics are typically prescribed for heart failure or severe fluid retention rather than standard hypertension. If you are taking one alongside other cardiovascular medications, the risk of cumulative depletion is significant.
Diuretics do not just affect magnesium. They increase potassium loss through the same fluid-clearing mechanism, and the two minerals are closely linked: a shortfall in one often will not correct until the other is addressed. See our guide to magnesium and potassium for more on why they travel together.
ACE inhibitors and ARBs
ACE inhibitors (lisinopril, ramipril, perindopril) and angiotensin receptor blockers (losartan, candesartan) have a different profile. They work on the renin-angiotensin-aldosterone system rather than on fluid volume, and they do not cause significant magnesium loss through the kidneys.
Some evidence suggests ACE inhibitors may even have a mild magnesium-sparing effect (Gröber et al., 2015). If you are on lisinopril or ramipril alone, magnesium depletion from the medication itself is less of a concern, though other factors like diet, stress, and gut absorption still apply.
Beta-blockers and calcium channel blockers
Beta-blockers (bisoprolol, atenolol) and calcium channel blockers (amlodipine, diltiazem) do not appear to have a direct effect on magnesium excretion. Their mechanisms of action do not involve the renal transporters that regulate magnesium levels.
That said, many people with hypertension are on combination therapy: for example, a thiazide alongside an ACE inhibitor. In those cases, the diuretic component is still depleting magnesium even if the other medications are not.
Signs your magnesium may be low
The symptoms of low magnesium are easy to miss or attribute to something else. Muscle cramps, poor sleep, fatigue, heart palpitations, and difficulty concentrating are among the most commonly reported signs.
A standard serum magnesium blood test will often return a normal result even when levels are genuinely low. This is because serum magnesium reflects less than 1% of total body stores: most magnesium is held inside cells and bone (Jahnen-Dechent & Ketteler, 2012). A normal blood test does not rule out functional deficiency.
For a detailed breakdown of symptoms to watch for, see our guide to signs of magnesium deficiency.
Can you take magnesium with blood pressure medication?
The research does not indicate that magnesium supplements interfere with the efficacy of standard blood pressure medications. There is no evidence that magnesium blunts the effect of thiazides, ACE inhibitors, or beta-blockers when taken in normal supplemental doses.
However, magnesium can interact with other medications. It can reduce the absorption of some antibiotics and thyroid medications if taken at the same time. Timing matters. Your pharmacist is the right person to advise on spacing if you take multiple medications.
If you are on long-term thiazide or loop diuretic therapy, it is worth raising magnesium levels with your GP directly. Some GPs already monitor for hypomagnesaemia in patients on long-term diuretics, particularly in older adults, but it is not universally checked.
For more on which medications can deplete magnesium, including PPIs, metformin, and certain antibiotics, see our post on what depletes magnesium.
Choosing the right form of magnesium
Not all magnesium supplements behave the same way. Magnesium oxide and citrate are commonly sold as high-dose options, but both can cause loose stools, especially at the doses needed to meaningfully raise levels. For people managing other medications and health conditions, gut disruption is worth avoiding.
Magnesium glycinate (also called magnesium bisglycinate) binds magnesium to glycine, an amino acid. This chelated form is absorbed through a different pathway than ionic magnesium, making it gentler on the digestive system and generally better tolerated at therapeutic doses. It does not carry the laxative effect associated with oxide or citrate forms.
For context on why the form matters, see our post on buffered vs unbuffered magnesium. It explains why some glycinate products are blended with oxide and what to look for on a supplement label.
Epsilon Life’s Magnesium Glycinate uses pure non-buffered magnesium bisglycinate, with no oxide blending, at 55 mg elemental magnesium per capsule.
Summary
Thiazide and loop diuretics, two of the most prescribed blood pressure drug classes in the UK, are known to increase magnesium excretion through the kidneys. ACE inhibitors, ARBs, beta-blockers, and calcium channel blockers carry a lower risk of depletion.
If you are on long-term diuretic therapy, low magnesium symptoms are worth discussing with your GP, as standard blood tests may not reflect the full picture. Magnesium glycinate is typically the form best suited to supplementing alongside other medications, but always check with your pharmacist before adding any supplement to your routine.
Blood pressure medication is not the only long-term prescription linked to nutrient shortfalls. See our broader guide to medications that quietly deplete your nutrients after 40 for other common culprits.
Frequently asked questions
Can you take magnesium with blood pressure medication?
In most cases, yes. Magnesium supplements are not known to interfere with the efficacy of standard blood pressure medications. However, magnesium can affect the absorption of some other medications if taken at the same time. Speak to your pharmacist about timing, and inform your GP before adding any supplement.
Which blood pressure medications deplete magnesium?
Thiazide diuretics (such as bendroflumethiazide and indapamide) and loop diuretics (such as furosemide) are the main blood pressure medications associated with magnesium depletion. They increase magnesium excretion through the kidneys. ACE inhibitors, ARBs, beta-blockers, and calcium channel blockers carry a lower risk.
Does lisinopril deplete magnesium?
Lisinopril is an ACE inhibitor and does not significantly deplete magnesium. Unlike thiazide diuretics, ACE inhibitors work through the renin-angiotensin-aldosterone system and do not increase magnesium excretion through the kidneys. Some research suggests ACE inhibitors may have a mild magnesium-sparing effect.
How do I know if my blood pressure medication is lowering my magnesium?
Symptoms of low magnesium include muscle cramps, poor sleep, fatigue, heart palpitations, and anxiety. A standard serum magnesium blood test often returns normal results even when levels are genuinely depleted, as serum magnesium reflects less than 1% of total body stores. If you are on long-term diuretics and experiencing these symptoms, raise it with your GP.
Which form of magnesium is best to take with blood pressure medication?
Magnesium glycinate (bisglycinate) is generally recommended for people on multiple medications. It is well absorbed, gentle on the digestive system, and does not cause the loose stools associated with magnesium oxide or citrate. It is also less likely to compete with other medications for absorption compared to high-dose inorganic forms.
References
- Zhang X et al. (2016). Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials. Hypertension, 68(2), 324–333. doi:10.1161/HYPERTENSIONAHA.116.07664
- Quamme GA. (1997). Renal magnesium handling: New insights in understanding old problems. Kidney International, 52(5), 1180–1195. PubMed 9350641
- Ryan MP. (1984). Diuretics and potassium/magnesium depletion. Direction for treatment. American Journal of Medicine, 77(5A), 38–47. PubMed 6390188
- Gröber U et al. (2015). Magnesium in Prevention and Therapy. Nutrients, 7(9), 8199–8226. PMC4586582
- Jahnen-Dechent W & Ketteler M. (2012). Magnesium basics. Clinical Kidney Journal, 5(Suppl 1), i3–i14. PubMed 26069819
This article is for informational purposes only and does not constitute medical advice. If you are taking prescription medication, speak to your GP or pharmacist before adding any supplement to your routine. Do not adjust or stop your medication without medical guidance.
