--- title: Magnesium side effects: what to expect and watch for description: Magnesium side effects are usually mild, like loose stools or cramping. Here's what the research says about mood, weight gain and when to stop taking it. url: https://niyora.com/treatments/magnesium-side-effects/ --- - [Niyora](https://niyora.com/) - [Treatments](https://niyora.com/treatments/) - Magnesium side effects, including mood Treatments # Magnesium side effects, including mood Magnesium's side effects are usually mild: loose stools, nausea or stomach cramps, especially with citrate or oxide forms. There's no good evidence it worsens mood, and a controlled trial found it didn't outperform placebo for PMDD mood symptoms either. Most digestive side effects ease within a couple of weeks or stop once you change the form or dose. Updated 14 October 2026 Niyora editorial Mixed evidence Strength of evidence Mixed Trials disagree, or the effect is small. - None - Limited - Mixed - Moderate - Strong ## At a glance - The most common magnesium side effect is digestive upset, loose stools, diarrhea or cramping, especially with citrate or oxide forms. - No trial reviewed here found that magnesium worsens mood. A controlled trial of intravenous magnesium found no benefit over placebo for PMDD mood symptoms ( [5]). - Magnesium hasn't been linked to weight gain in these studies, though some people notice short-term bloating. - Digestive side effects usually ease within a week or two, though this timeline hasn't been studied directly for magnesium and PMS, or resolve by switching forms or taking it with food. - Stop and call a doctor if you notice an irregular heartbeat, severe drowsiness, muscle weakness or ongoing severe diarrhea. ## Strength of evidence Mixed evidence - None - Limited - Mixed - Moderate - Strong Trials on magnesium for PMS and PMDD mood symptoms are mixed: an IV magnesium trial found no benefit over placebo for PMDD ( [5]), while smaller trials and reviews suggest modest anxiety benefits in vulnerable groups ( [1], [2], [3], [7]). No consistent link between blood magnesium and PMS ( [8]). ## What are the side effects of magnesium? The most common magnesium side effects are digestive: loose stools, diarrhea, nausea and stomach cramps. They show up more with magnesium citrate or oxide, common supplement forms, and less with gentler forms like glycinate or taurate. The menstrual migraine trial cited here used a different compound, magnesium pyrrolidone carboxylate ( [4]). Less common effects include: - Mild drowsiness at higher doses - Interaction with certain antibiotics or blood pressure medicines - Rare muscle weakness or an irregular heartbeat, usually only with kidney problems or very high doses These side effects aren't dangerous for most healthy adults, just uncomfortable enough to make you stop taking it. | Form | Common side effect | What the trials found | | --- | --- | --- | | Citrate or oxide | Loose stools, diarrhea | Common supplement forms; the menstrual migraine trial cited here used magnesium pyrrolidone carboxylate instead ( [4], [6]) | | Glycinate or taurate | Milder on the stomach | Fewer digestive complaints reported | | Intravenous (clinical use only) | Infusion discomfort | No mood benefit over placebo for PMDD in one small trial ( [5]) | If stomach upset is the main problem, taking magnesium with food or splitting the dose into two smaller ones often helps. Our [magnesium dosage](https://niyora.com/treatments/magnesium-dosage/) page covers timing in more detail. Where this sits in your cycle Luteal phase Days 15 to 28 Day 1 Ovulation Day 28 ## Can magnesium affect your mood? There's no good evidence that magnesium supplements make mood worse. Most research has gone the other direction, testing whether magnesium can ease anxiety or premenstrual mood symptoms rather than cause them. A small controlled trial gave women with PMDD an intravenous magnesium infusion and found it was no better than placebo at easing mood symptoms ( [5]). Smaller trials and a few systematic reviews suggest a **modest** anxiety benefit in people already prone to anxiety, including some with PMS, but the quality of that evidence is weak and inconsistent ( [1], [2], [3], [7]). If your mood shifts after starting magnesium, it's worth tracking whether the timing lines up with your cycle rather than the supplement itself. That pattern, not the label on the bottle, is what tells you whether to keep taking it. Niyora is a PMS and PMDD support app. If you're not sure whether a low mood followed the magnesium or just your usual premenstrual window, its estimated PMS window can help you line the two up and see which one fits. What the research says Most of the anxiety trials recruited people already prone to anxiety, including some with PMS, so the results may not carry over the same way to everyone ( [1], [3]). Right now If you're deciding whether to stop tonight - 1 Check whether the side effect is digestive (loose stools, cramps) or something else, like an irregular heartbeat or severe drowsiness. - 2 If it's mild and digestive, try taking your next dose with food, or split it into two smaller doses. - 3 If it's severe, or you have kidney disease or take diuretics, skip the next dose and call your doctor or pharmacist. - 4 Write down what you noticed and when, so you can see the pattern over your next cycle instead of guessing. Niyora walks you through this when it happens: - Calm down - - See it another way - - Choose what to say ## Can magnesium cause weight gain? No trial included here linked magnesium supplementation to weight gain. Some people notice short-term bloating or water retention in the first week or two, which is different from gaining fat and usually passes on its own. Premenstrual bloating is common on its own, so it can be hard to tell whether magnesium added to it or you were just noticing your usual cycle pattern. Keeping a simple note of when bloating shows up, relative to your period, can help separate the two. If you're also taking hormonal birth control, an antidepressant, or another supplement, weight changes are more likely tied to those than to magnesium itself. At typical supplement doses, magnesium doesn't have a known effect on appetite or metabolism, so steady weight gain over weeks or months is unlikely to be caused by it alone. ## How long do magnesium side effects last? Digestive side effects like loose stools or cramping usually ease within a week or two as your gut adjusts to the dose, though this timeline hasn't been studied directly for magnesium and PMS. If they don't ease, switching forms or taking it with food often helps, or try lowering the dose or switching to a gentler form like glycinate. Effects on energy, sleep or mood take longer to judge fairly. Trials testing magnesium for PMS symptoms ran for two to four months before seeing meaningful change ( [4], [6]), so it's worth giving it at least that long before deciding it isn't working. Keeping a simple log of mood, sleep and digestion for those months makes the pattern easier to see than relying on memory. That's also roughly how long it takes to separate a real effect from the normal ups and downs of your cycle. Our page on [how long magnesium takes to work](https://niyora.com/treatments/how-long-does-magnesium-take-to-work/) goes through the full timeline, including what to expect week by week. ## When should you stop taking magnesium? Stop magnesium and check in with a doctor or pharmacist if you notice: - Severe or ongoing diarrhea that doesn't settle after lowering the dose - An irregular heartbeat, severe drowsiness or muscle weakness - You have kidney disease or take diuretics and haven't cleared magnesium with your doctor first - Your mood or premenstrual symptoms get worse, not better, after a full two to four month trial Most people who stop don't need to taper. Magnesium doesn't build up the way some medicines do, so most people can simply stop the next dose rather than tapering, though you should check with a doctor if you have kidney disease. If you switch to a different form, like moving from oxide to glycinate, you don't need a break in between unless your doctor says otherwise. This is different from stopping an SSRI or hormonal contraceptive, which usually needs a doctor's input first. When to see a doctor If this is affecting a week of every month, or you're having thoughts of hurting yourself, see a GP or gynecologist and bring two months of daily notes. ## What are the alternatives to magnesium? Magnesium is one of several options people try for PMS and PMDD, and the evidence for most of them is similarly mixed. A few alternatives have more consistent support, at least for some symptoms: - Calcium, which has more consistent trial support for easing physical PMS symptoms than magnesium (see [calcium for PMS](https://niyora.com/treatments/calcium-for-pms/)) - Vitex (chasteberry), studied for PMS symptoms with mixed results (see vitex for PMS) - Vitamin B6, which outperformed both magnesium and placebo for overall PMS symptom severity in one trial ( [6]) - SSRIs, which guidelines support and which some people take only in the luteal phase, with a doctor's guidance - Cognitive behavioral therapy (CBT), recommended in treatment guidelines for PMDD None of these are a guaranteed fix, and what works for one person's cycle doesn't always work for another's. Our page on [PMS treatment](https://niyora.com/treatments/pms-treatment/) covers the full range of options, and [supplements for PMDD](https://niyora.com/treatments/supplements-for-pmdd/) goes deeper on the supplement evidence specifically. From the research library ## Research on magnesium 98 studies in the library look at magnesium in PMS and PMDD. They were published from 1981 to 2026, and each one has a short summary of what was tested and found. 98 studies, 1981 to 2026 How strong the studies are Strong study design 8 Moderate study design 31 Early or limited evidence 59 - [Systematic review, 2025Do nutritional interventions help with emotional symptoms of PMS?Vitamin B6, calcium, and zinc consistently improved emotional PMS symptoms. Other nutrients like vitamin D, magnesium, and soy had insufficient evidence supporting their use.Strong study design](https://niyora.com/research/papers/effect-of-nutritional-interventions-on-the-psychological-symptoms-of-2025/) - [Systematic review, 2013Does Vitex (chaste tree) help PMS and PMDD symptoms?Most studies found Vitex better than placebo for PMS. For PMDD, results were mixed: one study showed it equal to fluoxetine, while another found fluoxetine more effective. Side effects were mild.Strong study design](https://niyora.com/research/papers/vitex-agnus-castus-extracts-for-female-reproductive-disorders-a-systematic-2013/) - [Systematic review, 2009Which herbs, vitamins and minerals help treat PMS?Only calcium has good evidence to work for PMS. Chasteberry and vitamin B6 may help, but most of the 62 products people try lack proper research.Strong study design](https://niyora.com/research/papers/herbs-vitamins-and-minerals-in-the-treatment-of-premenstrual-syndrome-a-2009/) - [Systematic review, 2007What treatments work for premenstrual syndrome?Many treatments have been studied for PMS, but researchers face a major challenge: there is no standard way to measure symptom severity, making it difficult to know which treatments truly work.Strong study design](https://niyora.com/research/papers/premenstrual-syndrome-2007/) - [Randomised trial, 2003What treatments work for PMS and PMDD?Several treatments work. Non-drug options include cognitive behavioral therapy, exercise, and supplements like calcium and magnesium. Many studies support SSRIs (taken daily or only before menstruation). Hormonal treatments that stop ovulation also help.Strong study design](https://niyora.com/research/papers/a-review-of-treatment-of-premenstrual-syndrome-and-premenstrual-dysphoric-2003/) - [Randomised trial, 2003What complementary and alternative medicines help with women's reproductive health issues?Acupressure helps with pregnancy nausea and calcium helps with PMS. Vitamin B6, ginger, magnesium, chaste-tree berry, low-fat diet, exercise, and fish oil show promise but need more research.Strong study design](https://niyora.com/research/papers/complementary-and-alternative-medicine-cam-in-reproductive-age-women-a-review-of-2003/) [See all 98 studies on magnesium](https://niyora.com/research/topics/treatment-magnesium/) ## Questions people ask What's the most common magnesium side effect? + The most common magnesium side effect is digestive upset: loose stools, diarrhea or cramping. It shows up more with magnesium citrate or oxide, common supplement forms, and less often with gentler forms like glycinate or taurate. The menstrual migraine trial cited here used a different compound, magnesium pyrrolidone carboxylate ( [4]). Can magnesium make PMDD symptoms worse? + There's no evidence that magnesium worsens PMDD symptoms. A small controlled trial of intravenous magnesium found it didn't improve mood symptoms any more than placebo in women with PMDD ( [5]), so it's unlikely to help or hurt mood meaningfully for most people. Does magnesium cause bloating before your period? + Magnesium can cause mild bloating or water retention in some people, separate from the bloating many notice before a period anyway. It usually passes within a few days and wasn't linked to long-term weight gain in the trials reviewed here. What dose of magnesium did research studies use? + Doses vary by study. One trial testing magnesium for menstrual migraine used 360 mg a day starting mid-cycle ( [4]). There's no single proven dose for PMS or PMDD, so check our magnesium dosage page for how studies typically dosed it. Should I stop magnesium if I feel more anxious? + If anxiety increases after starting magnesium, it's more likely coincidental than causal, since trials haven't found magnesium worsens anxiety. Track it for a few cycles to see if the timing matches your usual premenstrual pattern before deciding to stop. ## Sources - 1. [The Effects of Magnesium Supplementation on Subjective Anxiety and Stress-A Systematic Review](https://doi.org/10.3390/nu9050429), Nutrients, 2017 - 2. [Examining the Effects of Supplemental Magnesium on Self-Reported Anxiety and Sleep Quality: A Systematic Review](https://doi.org/10.7759/cureus.59317), Cureus, 2024 - 3. [The effects of magnesium supplementation on subjective anxiety](https://doi.org/10.1684/mrh.2016.0411), Magnesium research, 2016 - 4. [Magnesium prophylaxis of menstrual migraine: effects on intracellular magnesium](https://doi.org/10.1111/j.1526-4610.1991.hed3105298.x), Headache, 1991 - 5. [Magnesium (mg) retention and mood effects after intravenous mg infusion in premenstrual dysphoric disorder](https://doi.org/10.1016/j.biopsych.2005.07.022), Biological psychiatry, 2006 - 6. [Effects of magnesium and vitamin b6 on the severity of premenstrual syndrome symptoms](https://doi.org/10.5681/jcs.2012.026), Journal of caring sciences, 2012 - 7. [The impact of essential fatty acid, B vitamins, vitamin C, magnesium and zinc supplementation on stress levels in women: a systematic review](https://doi.org/10.11124/jbisrir-2016-002965), JBI database of systematic reviews and implementation reports, 2017 - 8. [The Association Between Serum Magnesium and Premenstrual Syndrome: a Systematic Review and Meta-Analysis of Observational Studies](https://doi.org/10.1007/s12011-019-01672-z), Biological trace element research, 2019 Ask AI about this page Copy prompt ChatGPT ↗ Claude ↗ Perplexity ↗ Google AI Mode ↗ Grok ↗ On this page - [What are the side effects of magnesium?](#what-are-the-side-effects-of-magnesium) - [Can magnesium affect your mood?](#can-magnesium-affect-your-mood) - [Can magnesium cause weight gain?](#can-magnesium-cause-weight-gain) - [How long do magnesium side effects last?](#how-long-do-magnesium-side-effects-last) - [When should you stop taking magnesium?](#when-should-you-stop-taking-magnesium) - [What are the alternatives to magnesium?](#what-are-the-alternatives-to-magnesium) - [Research](#research) - [Questions](#faq) Niyora PMS & PMDD support For the hard moment before your period. Private, no account. [Get it on iPhone](https://apps.apple.com/app/niyora-pms-emotions/id6764561688) ## Keep reading Treatment Magnesium supplement for PMS: does it work? Treatment Magnesium for PMDD: does it work? Treatment Magnesium dosage for PMS and PMDD: how much to take Treatment How long does magnesium take to work? Treatment PMS treatment: what actually helps Condition What is PMS? Premenstrual syndrome, explained Guide Magnesium, calcium, vitamin D Treatment Supplements for PMDD: what actually helps Treatment Calcium supplements for PMS: does it work?