Last updated: October 2026
Magnesium can help with bloating when constipation is part of the cause. Magnesium citrate draws water into the bowel and acts as a gentle laxative, which can ease that tight, full feeling. If your bloating is not linked to constipation the evidence is weaker, and too much magnesium can itself cause wind and loose stools.
Below: what the research actually shows, which type of magnesium to choose, how much to take, when magnesium can make bloating worse, and the signs that mean you should see a GP.
Quick answer: which magnesium is best for bloating?
| If your bloating is… | Try |
|---|---|
| Bloating with constipation | Magnesium citrate: draws water into the bowel and acts as a gentle laxative |
| Bloating before your period | Daily magnesium for at least 2 cycles; a trial used 200mg a day |
| Sensitive stomach | Magnesium glycinate: gentler, less likely to loosen stools |
| Trapped wind | Magnesium is unlikely to help; carbonate can even add gas |
Does magnesium help with bloating?
It depends on what is causing your bloating. Bloating has many causes, including constipation, swallowing air, food intolerances, irritable bowel syndrome (IBS) and periods. Magnesium is most useful for two of them:
- Bloating from constipation. In a 2021 controlled trial of 90 adults with long-term constipation, 68% of those taking magnesium (as magnesium oxide) for four weeks said their symptoms improved overall, compared with 12% on a placebo.
- Bloating before a period. A University of Reading trial found that 200mg of magnesium a day reduced premenstrual bloating and other fluid retention symptoms by the second month.
For bloating caused by trapped wind or food intolerances, there is little evidence that magnesium helps, and changes to how and what you eat usually make more difference.
Read more: magnesium for constipation
For wider gut habits, see how to improve gut health.
How magnesium works on bloating
Magnesium affects your gut in three main ways:
- It draws water into the bowel. Forms such as citrate and oxide pull water into the intestines, which softens stools and helps things move. This is why magnesium is used as a laxative, and why it eases bloating that comes from being backed up.
- It helps muscles relax. Magnesium contributes to normal muscle function, including the muscles in your digestive tract.
- It neutralises stomach acid. Some magnesium compounds, such as magnesium hydroxide and carbonate, are used in antacids for indigestion and heartburn.
Which magnesium is best for bloating?
Start with the likely cause of your bloating, then choose the form that suits it.
| Form | Effect on the gut | Best for |
|---|---|---|
| Citrate | Gentle laxative effect, well absorbed | Bloating with constipation |
| Oxide | Stronger laxative effect, poorly absorbed | Short-term constipation relief |
| Hydroxide (milk of magnesia) | Laxative and antacid | Occasional constipation or indigestion |
| Glycinate / bisglycinate | Very gentle, rarely loosens stools | Topping up magnesium without a laxative effect |
| Malate | Gentle | General top-up during the day |
For bloating with constipation, citrate is the usual first choice: it works more gently than oxide. If your gut is sensitive and you want magnesium for other reasons, such as sleep, glycinate is less likely to upset your stomach.
Our Magnesium Glycinate Sleep Complex combines bisglycinate with citrate and gives 148mg of magnesium per serving. It is designed as an evening drink rather than a laxative. For a full comparison of every form, see our guide to the types of magnesium.
How much magnesium to take for bloating, and how long it takes
The NHS says adults need 300mg (men) or 270mg (women) of magnesium a day, mostly from food, and that 400mg or less a day from supplements is unlikely to cause harm. Taking more than 400mg can cause diarrhoea.
- Start low: around 100 to 200mg of elemental magnesium a day, and increase slowly if needed.
- Count everything: antacids and laxatives that contain magnesium count towards your total.
- Timing: for constipation, the laxative effect of citrate usually shows within a day or two. For premenstrual bloating, the Reading trial saw benefits in the second month of daily use.
Read more: how long magnesium takes to work
Can magnesium cause bloating?
Yes, sometimes. Because some forms draw water into the bowel, too much magnesium, or a sudden large dose, can cause wind, cramping, loose stools and, ironically, bloating. People with IBS or a sensitive gut are more likely to notice it.
If magnesium seems to make you bloated:
- lower the dose or split it across the day
- take it with food
- switch from citrate or oxide to glycinate, which is gentler
- speak to a pharmacist if it carries on
Bloating before your period
Premenstrual bloating is one of the most common reasons women try magnesium. In the University of Reading trial, 38 women took 200mg of magnesium or a placebo every day for two cycles. There was no difference in the first month, but by the second month the magnesium group had fewer fluid retention symptoms, including bloating, swollen hands and feet, and breast tenderness.
If your bloating is more puffiness and swelling than a tight, gassy stomach, our guide to magnesium for water retention goes into more detail, and magnesium for PMS covers cramps and mood too.
Other things that help bloating
Magnesium works best alongside simple changes:
- Eat smaller meals, slowly. Rushing swallows air.
- Cut back on fizzy drinks and chewing gum. Both add air to your gut.
- Move every day. A walk after meals helps keep things moving.
- Add fibre gradually and drink plenty of water, especially if you are constipated.
- Keep a food diary. It helps you spot foods that bloat you, such as beans, onions or sprouts.
When to see a GP about bloating
The NHS advises seeing a GP if you feel bloated regularly, it keeps happening even after changing your diet, or you have bloating with unintentional weight loss or blood in your poo.
Ask for an urgent GP appointment or call 111 if you have bloating with vomiting, diarrhoea, constipation or a stomach ache, a high temperature, a swelling or lump in your tummy, or you cannot pee, poo or fart.
See also PMS symptoms.
FAQs
Is magnesium citrate good for gas and bloating?
Magnesium citrate can ease bloating caused by constipation, because it draws water into the bowel and helps things move. For trapped wind that is not linked to constipation, it is less likely to help.
Can magnesium glycinate cause gas and bloating?
It is unusual. Glycinate is the gentlest form on the gut. If it does bloat you, try a lower dose or take it with food.
Which magnesium is best for bloating?
For bloating with constipation, magnesium citrate is the usual first choice. For a gentle top-up that is unlikely to upset your stomach, choose glycinate.
How much magnesium should I take for bloating?
Start with around 100 to 200mg of elemental magnesium a day. The NHS says 400mg or less a day from supplements is unlikely to cause harm, counting antacids and laxatives that contain magnesium.
Does magnesium help with PMS bloating?
It may. In a University of Reading trial, 200mg of magnesium a day reduced premenstrual bloating and fluid retention by the second month of use.
Is milk of magnesia good for bloating?
Milk of magnesia (magnesium hydroxide) is a laxative and antacid, so it can help occasional constipation or indigestion. Follow the pack instructions and speak to a pharmacist before using it regularly.
Will magnesium help me lose weight if I feel bloated?
Magnesium does not burn fat. If it eases constipation or premenstrual fluid retention you may feel less bloated and a little lighter, but that is water and waste, not fat.
Is magnesium carbonate good for bloating?
Magnesium carbonate is used in some antacids for indigestion. It reacts with stomach acid and can release gas, so it isn’t a first choice if bloating and wind are your main problem.
Does magnesium cause bloating?
It can if you take too much, especially citrate or oxide, which can cause wind and loose stools. Glycinate is usually gentler. Reduce the dose or split it through the day.
How quickly does magnesium help bloating?
For bloating linked to constipation, citrate often works within a day or two. For premenstrual bloating, trials saw benefits from the second month of daily use.
Sources
- NHS. Bloating.
- NHS. Vitamins and minerals: magnesium.
- NHS. Laxatives.
- Morishita D et al (2021). Senna versus magnesium oxide for the treatment of chronic constipation: a randomized, placebo-controlled trial. American Journal of Gastroenterology.
- Walker AF et al (1998). Magnesium supplementation alleviates premenstrual symptoms of fluid retention. Journal of Women’s Health.
This guide is general information, not medical advice.
