Last updated: October 2026
Magnesium may help with mild water retention, especially the bloating and puffiness some women get before a period, where small studies found it eased symptoms. Most studies used 200 to 400mg a day. It won’t fix swelling caused by heart, kidney or liver problems, so see your GP if swelling is new, painful or only on one side.
This guide covers what the research really shows, whether magnesium can cause water retention, the best type to choose, how much to take, simple ways to ease swollen ankles and feet, and when swelling needs a doctor.
Quick answer: best magnesium for water retention and swollen feet
| If you have… | What to try |
|---|---|
| Puffiness before your period | Daily magnesium for at least 2 cycles; a trial used 200mg a day |
| Everyday use | Glycinate or citrate: well absorbed; glycinate is gentler on the stomach |
| Swollen feet and ankles | Raise your legs, move regularly and cut down on salt. Magnesium is not a proven fix |
| Swelling in one leg, or with pain or breathlessness | See a GP urgently |
Does magnesium help with water retention?
Water retention, or oedema, is when fluid builds up in the body’s tissues, usually in the feet, ankles, legs, hands or face. The clearest evidence for magnesium is for the kind many women get before their period.
In a trial at the University of Reading, 38 women took 200mg of magnesium or a placebo every day for two menstrual cycles. There was no difference in the first month, but in the second month the magnesium group had fewer fluid retention symptoms: less weight gain, less swelling of the hands and feet, less breast tenderness and less abdominal bloating.
For water retention with other causes, such as hot weather or long periods of standing, there is little direct research on magnesium. It plays a part in keeping your body’s fluid and mineral balance steady, so topping up a low intake makes sense, but it is not a proven fix.
Read more: magnesium for bloating and magnesium for PMS
Does magnesium cause water retention?
There is no good evidence that magnesium supplements make you retain water. If anything, forms such as citrate draw water into the bowel and can loosen stools, which is the opposite effect. If you notice swelling after starting any supplement, stop it and speak to a pharmacist, as something else may be going on.
Best magnesium for water retention
No single form has been proven best for water retention. The trial above used magnesium oxide, but better-absorbed forms are a sensible choice for everyday use.
| Form | Absorption | Gentle on the gut? | Good to know |
|---|---|---|---|
| Citrate | Good | Can loosen stools | A popular first choice, especially with bloating |
| Glycinate / bisglycinate | Good | Yes, very | A gentle all-rounder that also suits evenings and sleep |
| Malate | Good | Yes | Often taken in the daytime |
| Chloride | Good | Moderate | Also sold as sprays and oils for the skin |
| Oxide | Poor | Often loosens stools | Cheap, and used in the Reading trial |
Our Magnesium Glycinate Sleep Complex combines bisglycinate and citrate, giving 148mg of magnesium per serving as an evening drink. For every form side by side, see our guide to the types of magnesium or magnesium glycinate vs other forms.
How much magnesium to take for water retention, and how long it takes
Most studies on fluid retention used 200 to 400mg of magnesium a day. The NHS says adults need 300mg (men) or 270mg (women) a day, mostly from food, and that 400mg or less a day from supplements is unlikely to cause harm. Higher doses can cause diarrhoea.
- Check the elemental amount on the label, not the weight of the compound.
- Give it time. In the Reading trial, the benefit appeared in the second month, so try it for at least two cycles.
- Take it daily. Your body clears extra magnesium within a day or two, so consistency matters.
Read more: how long magnesium takes to work and the best time to take magnesium
Magnesium for swollen feet and ankles: causes and what helps
Mild swelling in both ankles or feet is common and often harmless. Everyday causes include standing or sitting for a long time, hot weather, eating a lot of salty food, periods, pregnancy and some medicines. If you are pregnant, read our guide to magnesium in pregnancy and speak to your midwife before taking supplements.
The NHS suggests these simple steps to ease swelling:
- raise your legs on a chair or pillows when you can
- get some gentle exercise, such as walking, to help your circulation
- wear wide, comfortable shoes with a low heel and soft sole
- wash, dry and moisturise your feet
- avoid standing or sitting for long periods, and avoid tight socks, clothes or shoes
Magnesium creams, sprays and oils are popular for tired legs and feet. There is little evidence that much magnesium is absorbed through the skin, but the massage itself and raising your feet afterwards can help you feel more comfortable.
When swelling needs a doctor
Supplements are not the answer for every kind of swelling. The NHS advises:
- See a GP if both ankles, feet or legs are swollen and it has not improved after a few days of home treatment, it is getting worse, or you have a heart, kidney or leg vein condition.
- Get an urgent GP appointment or call 111 if only one ankle, foot or leg is swollen and you don’t know why, the swelling follows an injury, or it is severe, painful or getting worse.
- Call 999 if swelling comes with shortness of breath, a tight, heavy or painful chest, coughing up blood, palpitations, or feeling faint or clammy. This could be a blood clot in the lungs.
How to choose a quality magnesium supplement
- Choose brands that publish third-party lab reports for every batch.
- Check the elemental magnesium per serving, not just the compound weight.
- Pick a well-absorbed form such as citrate or glycinate.
- Look for vegan, non-GMO products without unnecessary fillers.
- Count magnesium from every product you take, including multivitamins and antacids, and stay at 400mg or less a day from supplements.
See also PMS symptoms.
FAQs
Does magnesium glycinate help with water retention?
It may help if your water retention is linked to your period or a low magnesium intake. Glycinate is well absorbed and gentle on the stomach, which makes it easy to take every day.
Is magnesium citrate good for water retention?
Citrate is a well-absorbed, popular choice, especially if you also feel bloated. It can loosen stools, so start with a low dose.
Does magnesium make you retain water?
There is no good evidence that it does. Some forms, such as citrate, draw water into the bowel instead, which can loosen stools.
Does magnesium help with swollen ankles?
It may help mild swelling linked to your period. For swollen ankles from standing, heat or other causes, raising your legs, moving more and comfortable shoes are more reliable. See a GP if swelling doesn’t settle or is only on one side.
Does magnesium reduce water weight?
If magnesium eases premenstrual fluid retention you may feel lighter and less puffy. That is water, not fat, and the effect is usually modest.
How long does magnesium take to work for water retention?
In the University of Reading trial, the benefit appeared in the second month of daily use, so give it at least two cycles.
Do magnesium creams and sprays work for swollen ankles?
There is little evidence that much magnesium is absorbed through the skin. The massage and putting your feet up can still help you feel more comfortable.
Which magnesium is best for swollen feet?
No form is proven best. Glycinate and citrate are well absorbed, but for swollen feet, raising your legs, walking and less salt help more. See a GP if swelling is new or one-sided.
Does Magnesium Freeze work for oedema?
Magnesium creams and gels such as Magnesium Freeze are popular for swollen legs, but there’s little evidence that magnesium absorbs through the skin in useful amounts. Any relief is more likely to come from the massage and cooling.
What is the best magnesium for edema?
Edema is the US spelling of oedema. No magnesium is proven to treat it. Oedema from heart, kidney or liver problems needs medical treatment, so see your GP.
Sources
- NHS. Swollen ankles, feet and legs (oedema).
- NHS. Vitamins and minerals: magnesium.
- 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.
