How many mg is too much magnesium glycinate? Understanding safe dosage

December 25, 2025 •

3 min read

The Tolerable Upper Intake Level (UL) for supplemental magnesium in adults is 350 mg per day, according to the NIH Office of Dietary Supplements. While magnesium glycinate is well-regarded for its high absorption and gentle effect on the stomach, exceeding this threshold can increase the risk of adverse effects.

Quick Summary

For adults, the safe daily upper intake for supplemental elemental magnesium, including magnesium glycinate, is 350 mg to avoid side effects. Exceeding this limit, particularly for individuals with kidney issues, increases the risk of toxicity (hypermagnesemia).

Key Points

Elemental Mg is Key: The Tolerable Upper Intake Level (UL) of 350 mg applies to elemental supplemental magnesium, not the total magnesium glycinate dosage.
High Doses, High Risk: Exceeding 350 mg of supplemental elemental magnesium can cause side effects like diarrhea, nausea, and abdominal cramps.
Serious Overdose: Very high doses can lead to severe conditions, including muscle weakness, low blood pressure, and irregular heartbeat.
Kidney Health is Crucial: Individuals with impaired kidney function are at a higher risk for magnesium toxicity and must exercise extreme caution.
Consult Your Doctor: Always talk to a healthcare professional before taking magnesium supplements, especially if you have existing health conditions or take other medications.
Glycinate is Gentle: Magnesium glycinate is generally less likely to cause digestive side effects compared to other forms like magnesium oxide.

Magnesium is a vital mineral involved in over 300 enzymatic reactions throughout the body, playing a crucial role in functions from energy production to muscle relaxation. Magnesium glycinate is a chelated form, meaning magnesium is bound to the amino acid glycine. This binding increases its bioavailability, making it well-absorbed by the body while minimizing the gastrointestinal side effects common with other forms, such as magnesium oxide or citrate. However, even with this gentler form, it is crucial to understand the safe dosage limits to prevent overconsumption.

The Critical Difference: Total vs. Elemental Magnesium

When determining how much magnesium is too much, it is essential to distinguish between the total amount of the supplement and the amount of elemental magnesium it contains. The Tolerable Upper Intake Level (UL) refers specifically to the elemental magnesium from supplements, not the total weight of the compound. Magnesium glycinate typically contains about 14% elemental magnesium by weight. For instance, a 1000 mg serving of magnesium glycinate provides approximately 140 mg of elemental magnesium.

What is the Tolerable Upper Intake Level (UL)?

For healthy adults, the Tolerable Upper Intake Level (UL) for supplemental elemental magnesium is set at 350 mg per day. This UL applies only to magnesium from dietary supplements and medication, not from food or drinking water, as the body can efficiently excrete excess magnesium from food. Exceeding the 350 mg supplemental UL increases the risk of adverse effects.

Signs You're Taking Too Much Magnesium Glycinate

While magnesium glycinate is highly tolerable, overconsumption can lead to side effects. Mild symptoms may include diarrhea, nausea, abdominal cramps, headache, or flushing. More serious signs of hypermagnesemia (high magnesium levels) include muscle weakness, low blood pressure, irregular heartbeat, confusion, lethargy, and in severe cases, breathing difficulties or cardiac arrest.

Comparison of Magnesium Glycinate with Other Forms

Magnesium glycinate is often preferred due to its high absorption and minimal gastrointestinal distress compared to forms like magnesium oxide which is poorly absorbed and can cause diarrhea. Magnesium citrate offers good absorption but can also have a laxative effect.


Feature	Magnesium Glycinate	Magnesium Citrate	Magnesium Oxide
Absorption	Excellent; highly bioavailable.	Good absorption, but can act as a laxative.	Poorly absorbed by the body.
Best For	Relaxation, sleep, anxiety, muscle calmness.	Constipation relief, muscle cramps.	Heartburn relief, occasional constipation.
Side Effects	Minimal gastrointestinal distress due to high absorption.	May cause loose stools or diarrhea.	High risk of causing diarrhea and bloating.
Effect	Calming, promotes relaxation.	Laxative, promotes bowel movement.	Mild antacid.

Factors That Affect Your Personal Maximum Dose

Your individual tolerance is influenced by factors like kidney function (impaired kidneys increase risk of hypermagnesemia) and existing medical conditions. Magnesium can also interact with certain medications, affecting absorption or increasing magnesium levels.

When to Consult a Healthcare Professional

Given individual variations and potential interactions, consulting a doctor or dietitian before starting or changing a magnesium supplement is crucial. This is especially important for those with pre-existing conditions, older adults, or pregnant/breastfeeding women.

Conclusion: Finding the Right Balance

Adhering to the 350 mg elemental magnesium UL for supplements is crucial for healthy adults. Be aware of overconsumption signs and consider individual factors like kidney health and medication use. Consulting a healthcare provider ensures a safe and effective approach to magnesium supplementation.

For more detailed information on magnesium, consult the National Institutes of Health Office of Dietary Supplements.

A Note on Authoritative Sources

This article's information is based on reputable sources including government health bodies and medical publications.

Frequently Asked Questions

While 500 mg of magnesium glycinate provides approximately 70 mg of elemental magnesium (below the 350 mg UL), the total dosage can vary. Always confirm the elemental content with your healthcare provider, especially if you take other magnesium supplements or have kidney issues.

The most common early signs of excessive magnesium intake are gastrointestinal issues such as diarrhea, nausea, and abdominal cramps. While glycinate is gentler, high doses can still trigger these symptoms.

Magnesium glycinate is a chelated compound where magnesium is bound to glycine. It contains approximately 14% elemental magnesium by weight. So, a 1000 mg dose of magnesium glycinate would have around 140 mg of elemental magnesium.

Yes, magnesium glycinate is generally better tolerated and less likely to cause digestive side effects like diarrhea compared to magnesium oxide, which is poorly absorbed and has a strong laxative effect.

Individuals with kidney disease, heart block, or certain intestinal diseases should avoid magnesium supplements unless directed by a doctor. Those on antibiotics, diuretics, or other medications should also consult a professional.

Yes, it is generally safe for most healthy adults to take magnesium glycinate daily, provided the supplemental elemental magnesium dose does not exceed the 350 mg UL.

While magnesium toxicity (hypermagnesemia) is rare in healthy individuals, very high doses of magnesium supplements can lead to serious health complications, including dangerously low blood pressure, respiratory distress, and cardiac arrest, which can be fatal.