Can Magnesium Cause Nausea or Vomiting? Understanding the Side Effects

November 16, 2025 •

4 min read

Side effects like nausea and vomiting from magnesium supplements typically occur at doses larger than 350 milligrams, a quantity that exceeds the Tolerable Upper Intake Level for most adults. Understanding how and why this can happen is crucial for a comfortable supplementation routine, especially for those sensitive to digestive upset.

Quick Summary

High doses or poorly absorbed forms of magnesium supplements, like oxide and citrate, can cause nausea and vomiting. Taking supplements with food or opting for a more bioavailable type can minimize gastrointestinal side effects.

Key Points

Dosage Matters: High doses of magnesium, especially over 350 mg from supplements, significantly increase the risk of nausea and digestive upset.
Form Selection is Key: Less bioavailable forms like magnesium oxide and citrate are more likely to cause nausea, while highly absorbable forms such as glycinate are gentler on the stomach.
Take with Food: Consuming your magnesium supplement with a meal can help minimize stomach irritation and prevent feelings of nausea.
Start Low and Go Slow: If you are new to magnesium supplements, start with a low dose and gradually increase it as your body adjusts.
Watch for Toxicity Signs: Severe symptoms like muscle weakness, low blood pressure, and irregular heartbeat can indicate magnesium toxicity and require immediate medical attention.
Kidney Function is Critical: Individuals with kidney problems are at a higher risk of magnesium toxicity because their bodies cannot properly excrete excess mineral levels.

Magnesium is an essential mineral involved in over 300 biochemical reactions in the body, supporting everything from nerve and muscle function to bone health. While generally safe and well-tolerated, some individuals experience adverse gastrointestinal effects, including nausea and vomiting, after taking magnesium supplements. This discomfort is often related to the dosage, the specific form of magnesium, and individual sensitivity. Fortunately, by understanding these factors, you can take steps to minimize or prevent these unwanted side effects.

The Direct Link Between Magnesium Supplements and Nausea

The connection between magnesium supplements and digestive upset, such as nausea and vomiting, is well-documented. This reaction is often caused by two primary factors: the osmotic effect and local irritation within the digestive tract.

Osmotic Effect: Magnesium draws water into the intestines. While beneficial for relieving constipation, this osmotic action can lead to cramping, bloating, and a feeling of sickness that can manifest as nausea or vomiting, especially with high doses.
Dosage Sensitivity: The risk of gastrointestinal side effects increases significantly with higher doses of supplemental magnesium, particularly above the Tolerable Upper Intake Level (UL) of 350 mg for adults. Healthy kidneys can typically excrete excess magnesium, but exceeding this level increases the likelihood of symptoms. Very high doses, exceeding 5,000 mg per day, can even lead to magnesium toxicity.
Empty Stomach Irritation: Taking magnesium supplements on an empty stomach can sometimes cause irritation to the gastrointestinal lining, leading to nausea. Consuming the supplement with a meal can help mitigate this discomfort.

Comparison of Magnesium Forms and Their Impact on Digestion

Not all magnesium supplements are created equal, and their chemical form plays a significant role in how well they are absorbed and whether they cause digestive upset. Different forms have varying bioavailability, with some being more prone to causing laxative effects and nausea than others.

Form vs. Bioavailability: What's the Difference?

Bioavailability refers to the amount of magnesium that is effectively absorbed by your body. Forms with low bioavailability mean more unabsorbed magnesium sits in the intestines, which can lead to discomfort. Magnesium glycinate, for example, is highly bioavailable and gentle, whereas magnesium oxide has low bioavailability, making it a powerful laxative.


Magnesium Form	Common Uses	Bioavailability	Likelihood of Causing Nausea	Reason for Digestive Effect
Magnesium Oxide	Constipation, heartburn, migraines	Very Low	High	Poor absorption means more unabsorbed magnesium causes osmotic effects.
Magnesium Citrate	Constipation, general supplementation	Good	Moderate to High (dose-dependent)	Laxative properties draw water into intestines, especially at higher doses.
Magnesium Glycinate	Sleep, anxiety, muscle relaxation	High	Very Low	Highly absorbable and less likely to cause digestive distress.
Magnesium Malate	Energy production, fibromyalgia	High	Low	Well-absorbed and less of a laxative effect than other forms.
Magnesium Chloride	General supplementation, topical use	Good	Moderate	Can still cause digestive upset, but well-absorbed.

How to Prevent Magnesium-Related Nausea

If you find yourself experiencing nausea after taking a magnesium supplement, there are several simple strategies to employ that can often resolve the issue without abandoning supplementation entirely.

Take with Food: As a general rule, taking your magnesium supplement with a meal can significantly reduce the risk of stomach irritation and nausea.
Adjust Your Dosage: Consider reducing your dosage, especially if you are taking more than 350 mg per day. Start with a lower dose and gradually increase it to find a level your body can tolerate.
Choose a Different Form: Switch to a more bioavailable and gentle form of magnesium, such as magnesium glycinate or malate. These forms are less likely to have a strong laxative effect.
Divide the Dose: Instead of taking a large dose all at once, try splitting it into two or more smaller doses throughout the day.
Consider Topical or Other Methods: For some, topical magnesium sprays or creams applied to the skin may provide relief without impacting the digestive system.

When to See a Doctor

While mild nausea from magnesium is often manageable with dose or form adjustments, it's important to be aware of the signs of more serious magnesium toxicity (hypermagnesemia), particularly for individuals with impaired kidney function. Symptoms can progress from mild digestive issues to more severe problems. Seek immediate medical attention if you experience:

Severe or persistent vomiting
Irregular or slow heart rate
Profound muscle weakness or fatigue
Trouble breathing
Dizziness or confusion
Extremely low blood pressure

Conclusion

Magnesium supplements can indeed cause nausea or vomiting, but this side effect is typically linked to high doses or less bioavailable forms like magnesium oxide. For most individuals, simply adjusting the dose, taking the supplement with food, or switching to a gentler form such as magnesium glycinate can effectively prevent digestive discomfort. If symptoms persist or worsen, or if you have pre-existing kidney issues, it is essential to consult a healthcare professional to rule out more serious concerns. For further information, consult reliable sources like the NIH Fact Sheet on Magnesium.

Frequently Asked Questions

Magnesium glycinate is considered one of the best forms for those with sensitive stomachs, as it is highly absorbable and less likely to cause digestive side effects like nausea and diarrhea compared to other types.

Magnesium can cause nausea due to its osmotic effect, where it draws water into the intestines. This can lead to cramping, bloating, and irritation, which can trigger feelings of sickness.

Yes, taking magnesium supplements on an empty stomach can increase the risk of gastrointestinal irritation and lead to nausea or vomiting. Taking it with a meal helps to reduce this risk.

Mild nausea is often just a side effect of dosage or form and is usually not serious. However, persistent nausea combined with symptoms like muscle weakness, low blood pressure, or confusion can be a sign of toxicity and warrant immediate medical evaluation.

Paradoxically, a deficiency in magnesium can also cause nausea, along with other symptoms like fatigue and loss of appetite. It's important to differentiate between symptoms of deficiency and those of excess magnesium.

For most healthy adults, the Tolerable Upper Intake Level (UL) for supplemental magnesium is 350 mg per day. Taking doses above this amount increases the risk of side effects.

To reduce nausea, try taking your supplement with food, lowering your dosage, or switching to a more gentle form like magnesium glycinate. Dividing your total dose throughout the day can also help.