§.01What citrate actually is.
Magnesium citrate is magnesium ion bonded to citric acid. Compound weight is about 16% elemental magnesium, so a 400 mg dose delivers ~64 mg of elemental magnesium. Bioavailability is good (20-35% absorbed in healthy adults), comparable to glycinate.
The defining feature is osmotic activity in the gut. The citrate ion pulls water into the colon, which is why doses above ~250 mg of elemental magnesium reliably cause loose stools. This is not a defect; this is the pharmacology. High-dose citrate is sold as a laxative under brand names like Citroma for a reason (NIH ODS).
Most "magnesium did not work for me" stories are really "I took citrate at a laxative dose and got the laxative effect." It was working as designed; you just bought the wrong tool.Dr. Marthe Janssen, PharmD
§.02When to take citrate.
- Mild to moderate constipation. 200 to 300 mg elemental magnesium per day, taken on an empty stomach for fastest effect (ACG 2021 guideline).
- Pre-procedure bowel prep. Higher doses under clinician guidance. The 10-oz bottle at the pharmacy is for this; do not self-dose at that level.
- Budget-conscious general repletion if you tolerate the GI effect at modest doses (100 to 150 mg elemental). Some people do; many do not.
§.03When to skip citrate.
- Sleep, anxiety, stress. Glycinate is the form with the glycine carrier doing its own calming work at GABA receptors. Same elemental Mg, gut-gentle.
- Already-irritable gut. IBS, IBD, recent abdominal surgery. The osmotic load is unwelcome.
- Taking other GI-affecting medications. Magnesium binds tetracyclines, fluoroquinolones, and levothyroxine. Separate by 2 hours regardless of form.
- Pregnancy. The bowel effect during pregnancy is uncomfortable; glycinate is the standard pick.
§.04How it compares to other forms.
| Form | % elemental | Best for | Catch |
|---|---|---|---|
| Oxide | ~60% | Almost nothing | ~4% absorbed; mostly useless therapeutically |
| Citrate | ~16% | Constipation, budget repletion | Laxative at therapeutic doses |
| Glycinate | ~14% | Sleep, stress, cramps, repletion | Pay attention to elemental vs compound weight |
| Threonate | ~8% | Cognition, age-related decline | Expensive; preliminary evidence |
| Taurate | ~12% | Cardiovascular angle | Limited human trial data |
§.05Dose, timing, and how to know if it is working.
Standard protocol: 200 mg elemental magnesium from citrate, once daily, on an empty stomach for laxative effect or with food to dampen it. Effect appears within 6 to 24 hours of the first dose. If nothing moves at 200 mg after 48 hours, increase by 100 mg and try again the next day. Stay under 500 mg elemental per day total.
Re-evaluate after 2 weeks. If you are using citrate for chronic constipation rather than acute, address the underlying cause: fiber intake, water intake, movement, and any medications that slow gut motility (opioids, anticholinergics, some antidepressants).
"500 mg magnesium citrate" usually means ~80 mg elemental magnesium.
The compound weight on the front of the bottle is not the magnesium dose. Look at the supplement facts panel for the elemental mg figure, or do the math: compound dose × 0.16 ≈ elemental Mg.
§.06FAQ.
Magnesium citrate vs glycinate — which one?
Glycinate for sleep, anxiety, cramps, and most repletion needs. Citrate for constipation or budget-driven repletion if you tolerate the GI effect. They serve different use cases. Read our full comparison.
Can I take citrate and glycinate together?
Yes; many people do, especially if they have both stress/sleep concerns AND chronic constipation. Glycinate at dinner, citrate in the morning. Combined elemental Mg under 500 mg per day.
How long until citrate works?
Laxative effect: 6 to 24 hours. Repletion of tissue magnesium: 4 to 8 weeks. These are different timelines for different goals.
Is citrate safe long-term?
At reasonable doses (under 400 mg elemental daily) with normal kidney function, yes. Chronic mega-doses can dysregulate electrolytes. If you are using citrate as a daily laxative for more than a few weeks, talk to a clinician about the root cause.
§.99The bottom line.
Magnesium citrate is the right tool for constipation and pre-procedure bowel prep at 200 to 300 mg elemental per day. It is also a reasonable budget-friendly choice for general repletion if your gut tolerates it. For sleep, anxiety, cramps, and long-term repletion in most adults, glycinate is the better choice at a similar price. PuraVigor does not sell citrate because the cheaper pharmacy generics are perfectly adequate; we sell glycinate, which is the form 9 out of 10 readers actually need.
Magnesium Bisglycinate, 60 ct — at the apothecary.
Reviewed by Dr. Marthe Janssen, PharmD. Last updated May 19, 2026.
Disclaimer: this article is educational and does not substitute for advice from your prescriber. Statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.