Magnesium Supplements: Benefits, Types, Timing & Side Effects
Also known as: magnesium glycinate, magnesium citrate, best time to take magnesium, does magnesium make you poop
Magnesium is an essential mineral involved in hundreds of processes including muscle and nerve function, blood sugar control, and sleep — and many people don't get enough from diet. Supplements come in several forms that behave differently: glycinate is gentle and popular for sleep and relaxation, citrate and oxide are more likely to loosen stools (and are used for constipation), and threonate is marketed for the brain. Yes, magnesium — especially citrate and oxide — can make you poop, because unabsorbed magnesium draws water into the gut. Most adults need roughly 310–420 mg of total magnesium per day; supplemental doses of 200–400 mg of elemental magnesium are common, and it's often taken in the evening.
Common magnesium forms compared
| Magnesium glycinate | Gentle · well absorbedPopular for sleep, relaxation, and general use; least likely to cause diarrhea. |
| Magnesium citrate | Well absorbed · laxative effectAlso used to relieve constipation; can loosen stools. |
| Magnesium oxide | Poorly absorbed · strong laxativeCheap and high elemental content, but most passes through — often used for constipation. |
| Magnesium L-threonate | Marketed for the brainPromoted for cognition/memory; human evidence is still limited. |
| Magnesium malate / taurate | Gentle alternativesMalate sometimes used for energy; taurate for heart/blood pressure interest. |
Amounts on a label may be the compound weight, not elemental magnesium — check for 'elemental' to compare doses accurately.
What magnesium can help with
- Supports normal muscle and nerve function, energy metabolism, and blood sugar regulation.
- Correcting a deficiency can improve sleep quality, muscle cramps, and general well-being.
- Glycinate and other gentle forms are widely used to support relaxation and sleep onset.
- Citrate and oxide are used therapeutically for occasional constipation because of their laxative effect.
- Adequate magnesium is associated with healthy blood pressure and cardiovascular function.
Dosing and the best time to take magnesium
- Most adults need about 310–420 mg of total magnesium daily (from food plus supplements); typical supplemental doses are 200–400 mg of elemental magnesium.
- Best time: there's no strict rule, but many people take magnesium in the evening because it can feel calming and supports sleep. Consistency matters more than timing.
- For sleep or relaxation, glycinate 30–60 minutes before bed is a common choice.
- Take with food if it upsets your stomach; split into two smaller doses to improve tolerance and absorption.
- For constipation, citrate or oxide taken with plenty of water is more effective; for daily topping-up without loosening stools, choose glycinate.
- Space magnesium a couple of hours apart from certain antibiotics and thyroid medication, which it can bind.
Side effects and cautions
- The most common side effect is loose stools or diarrhea — most likely with citrate and oxide, least with glycinate.
- People with kidney disease should not supplement magnesium without medical guidance, because impaired kidneys can't clear excess.
- Very high doses can cause nausea, cramping, low blood pressure, and — rarely, in kidney impairment — dangerous magnesium buildup.
- Magnesium can reduce absorption of some antibiotics (tetracyclines, quinolones), bisphosphonates, and levothyroxine — separate the doses.
- The upper limit for supplemental magnesium in adults is 350 mg/day of elemental magnesium; the laxative threshold varies by person and form.
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Frequently asked questions
Does magnesium make you poop?
It can. Magnesium citrate and magnesium oxide draw water into the intestine and are used specifically to relieve constipation, so they commonly loosen stools. Magnesium glycinate is much gentler and less likely to cause this. If you want the benefits without the laxative effect, choose glycinate and take it with food.
What is the best time to take magnesium?
There's no strict best time, but many people take magnesium in the evening because it can feel calming and may support sleep. What matters most is taking it consistently. If it upsets your stomach, take it with food, and consider splitting it into two smaller doses.
What's the difference between magnesium glycinate and citrate?
Glycinate is well absorbed and gentle on the gut, making it popular for sleep and everyday use. Citrate is also well absorbed but has a stronger laxative effect, so it's a good choice if you also want help with constipation but more likely to loosen stools if you don't.
How much magnesium should I take per day?
Adults need roughly 310–420 mg of total magnesium daily from food and supplements combined. Typical supplement doses are 200–400 mg of elemental magnesium. The upper limit for supplemental (not food) magnesium is 350 mg/day, and people with kidney disease should check with a doctor first.
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Medically reviewed by Antonieta Rueda, MD and Kyle R. Toth, MD · Last reviewed July 6, 2026
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Dietary supplements are not regulated like medications, quality varies between products, and they can interact with prescription drugs and existing conditions. Talk to your doctor or pharmacist before starting any supplement, especially if you are pregnant, nursing, have a medical condition, or take other medications.