Most laxatives work. That isn't the issue. The issue is how they work, what they do to your gut over time, and whether you'll still be able to stop taking them in six months.
The short version
- Move uses two forms of magnesium, citrate and oxide, both of them osmotic
- Osmotic means it draws water into the bowel to soften stool, rather than forcing the bowel wall to contract
- The dose looks high because most of it is meant to stay in your gut rather than be absorbed. That's the mechanism, not a side effect
- No stimulants, so it doesn't lose its effect the longer you use it
- One to three scoops in water before bed. You decide where you land on the dosage.
If you want to know why each of those choices was made, and what the evidence behind them looks like, the rest of this article covers it.
Here are the four reasons Move works differently to most of what's on the shelf.
1. Two forms of magnesium, so it works whatever your stomach is doing
Move now uses two forms of magnesium: citrate and oxide. Both are osmotic laxatives, sometimes called saline laxatives. They don't whip your bowel into contracting. They change the water balance inside it.
Here's the mechanism. Magnesium oxide is converted to magnesium chloride by stomach acid, then to magnesium bicarbonate and magnesium carbonate by pancreatic secretions in the duodenum. Those compounds raise the osmotic pressure of the fluid in the intestinal lumen, which pulls water into the bowel and increases both the water content and the volume of the stool. The swollen stool then presses on the intestinal wall, which stimulates the bowel's own propulsive movement.[1]
So the softening and the movement come from the same action. There's no separate stimulant doing the pushing.
Why two forms rather than one? Magnesium oxide needs stomach acid to make that first conversion. In people taking PPIs or H2 blockers, gastric pH is higher, less magnesium chloride is generated, and the laxative effect measurably drops off.[1] That matters here, because a large number of people dealing with chronic constipation are also on acid-suppressing medication.
Magnesium citrate is already a highly soluble salt and doesn't depend on that acid conversion in the same way, which is also why it's more bioavailable than the oxide form.[2] Pairing the two means the formula still delivers whatever your stomach acid is doing.
2. The dose is high on purpose, and that's precisely the point
One scoop delivers 580 mg of magnesium. That is deliberately, unusually high for a supplement, and here's why it has to be.
Magnesium absorption is not a fixed percentage. It saturates. In a landmark study of magnesium absorption across a wide range of intakes, fractional absorption fell progressively from 65% at the lowest intake down to 11% at the highest.[3] The more you take at once, the smaller the proportion your body takes up.
Magnesium oxide is at the low end even before you account for that: its fractional absorption is around 4%, against 9 to 11% for other magnesium salts.[1] Pharmacokinetic work has shown roughly 85% of the magnesium from magnesium oxide leaving the body in the faeces.[1]
That is not a flaw in the ingredient. It is the entire mechanism. The magnesium that isn't absorbed is the magnesium that stays in your gut, holds water in the bowel and softens what's sitting there.
This is the distinction between Move and a general magnesium supplement. A magnesium capsule is designed to raise your magnesium status, and loose stools are its side effect. Move is designed to keep magnesium in the bowel, and that is its purpose.
3. Osmotic, not stimulant, so it doesn't stop working
This is the difference that matters most over months rather than days.
Stimulant laxatives based on anthraquinones, which is the category senna and rhubarb fall into, produce tolerance with continued use. You need more to get the same result. Magnesium oxide does not: patients do not develop tolerance with continuous use.[1]
And it isn't a trade of effectiveness for gentleness. In a randomised, double-blind, placebo-controlled trial comparing magnesium oxide against senna and placebo, the overall response rate was 68.3% for magnesium oxide, 69.2% for senna and 11.7% for placebo. Time to first spontaneous bowel movement was 17.9 hours for magnesium oxide and 18.8 hours for senna.[4]
Effectively identical to senna, without the tolerance.
A second randomised, double-blind, placebo-controlled trial in chronic constipation found a 70.6% response rate for overall symptom improvement with magnesium oxide against 25.0% for placebo, with improvements in spontaneous bowel movements, stool form, colonic transit time, abdominal symptoms and quality of life [5]
And a 2023 systematic review and meta-analysis from King's College London, which pooled the randomised trial evidence on supplements for chronic constipation, concluded that magnesium oxide supplements are effective at improving the cardinal symptoms of chronic constipation. The same analysis found insufficient evidence to support kiwifruit supplements.[6]
That last finding is a large part of why we reformulated. We would rather put the space in the tub behind the ingredient the evidence actually backs.
There's a second reason to be cautious with stimulant laxatives long term
Senna belongs to a group of plant compounds called hydroxyanthracene derivatives. The same family turns up in cascara sagrada, aloe latex, rhubarb root and frangula, also sold as buckthorn.
In 2018 the European Food Safety Authority reviewed these compounds and concluded they should be regarded as genotoxic and carcinogenic unless specific data demonstrate otherwise. It could not establish a daily intake it considered safe.[8] A further assessment in 2024, looking at additional data submitted on rhubarb, senna, frangula and cascara preparations, reached the same conclusion: safety could not be established from the studies provided.[9]
Two things worth saying plainly, because we'd rather give you the full picture than a frightening headline. That assessment concerns these plants as ingredients in food and supplements, and it is a "we can't rule this out" finding rather than proof of harm in people. And senna is still an authorised medicine for constipation in the UK. What's consistent across all of it, including the label on the box, is that it's intended for short-term use.
Which is fine if you need something for a few days. It's less fine if, like most people we speak to, constipation is something you've been managing for years.
Move contains no anthraquinones and nothing from any of those plants. Magnesium works by physics rather than by chemically prodding the bowel wall, and there's no equivalent long-term question hanging over it.
4. You set the dose, not the label
Constipation is not one condition and people do not need the same amount.
Take 1 to 3 scoops in 250 ml or more of water before bed. Start with one scoop. Increase the nightly dose until you get the bowel movement you're after, then stay there.
Most laxatives hand you a fixed dose and leave you to cope with whatever it does. Move is built to be titrated. You find your number and you stay at it. Some people never go past one scoop.
The water isn't optional, either. The whole mechanism is water movement into the bowel, so take it with a full glass at minimum, and drink through the day.
Who should check with a doctor first
We would rather say this plainly than bury it.
Kidney function. Your kidneys clear magnesium. Reduced kidney function, along with higher daily doses, is the main factor associated with raised blood magnesium levels in people using magnesium laxatives.[1] If you have any degree of kidney disease, speak to your GP before using Move.
Medications. Magnesium can bind to tetracycline and quinolone antibiotics and to bisphosphonates, reducing their effect. Leave at least two hours between Move and any of these, and the same applies to levothyroxine and iron supplements.[1]
On magnesium generally. NHS guidance is that having 400 mg or less a day of magnesium from supplements is unlikely to cause harm, and that higher short-term doses can cause loose stools.[7] Move sits above that figure by design, because the loosening effect is the point rather than a side effect, and because most of the magnesium is never absorbed. It is not intended as a daily magnesium supplement for correcting magnesium status. If you're already taking magnesium for muscle, sleep or energy, factor that in and talk to a healthcare professional.
As always, if constipation is new, persistent, or comes with pain, bleeding or unexplained weight loss, please see your GP rather than reaching for anything on our shelf.
References
- Mori H, Tack J, Suzuki H. Magnesium Oxide in Constipation. Nutrients. 2021;13(2):421. https://doi.org/10.3390/nu13020421
- Lindberg JS, Zobitz MM, Poindexter JR, Pak CY. Magnesium bioavailability from magnesium citrate and magnesium oxide. Journal of the American College of Nutrition. 1990;9(1):48-55. https://doi.org/10.1080/07315724.1990.10720349
- Fine KD, Santa Ana CA, Porter JL, Fordtran JS. Intestinal absorption of magnesium from food and supplements. Journal of Clinical Investigation. 1991;88(2):396-402. https://www.jci.org/articles/view/115317
- Morishita D, Tomita T, Mori S, et al. Senna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled Trial. American Journal of Gastroenterology. 2021;116(1):152-161. https://doi.org/10.14309/ajg.0000000000000942
- Mori S, Tomita T, Fujimura K, et al. A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation. Journal of Neurogastroenterology and Motility. 2019;25(4):563-575. https://doi.org/10.5056/jnm18194
- van der Schoot A, Creedon A, Whelan K, Dimidi E. The effect of food, vitamin, or mineral supplements on chronic constipation in adults: A systematic review and meta-analysis of randomized controlled trials. Neurogastroenterology & Motility. 2023;35(11):e14613. https://doi.org/10.1111/nmo.14613
- NHS. Vitamins and minerals: Others. https://www.nhs.uk/conditions/vitamins-and-minerals/others/
- EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). Safety of hydroxyanthracene derivatives for use in food. EFSA Journal. 2018;16(1):5090. https://doi.org/10.2903/j.efsa.2018.5090
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Scientific Opinion on additional scientific data related to the safety of preparations of Rheum palmatum L., Rheum officinale Baill. and their hybrids, Rhamnus purshiana DC., Rhamnus frangula L. and Cassia senna L. EFSA Journal. 2024;22(5):8766. https://doi.org/10.2903/j.efsa.2024.8766
