Magnesium Citrate vs. Magnesium Oxide

What's the Difference?

Magnesium Citrate and Magnesium Oxide are both commonly used as dietary supplements to increase magnesium levels in the body. However, they differ in terms of their chemical composition and effects on the body. Magnesium Citrate is a combination of magnesium and citric acid, which enhances its absorption in the body. It is known for its laxative properties and is often used to relieve constipation. On the other hand, Magnesium Oxide is a compound of magnesium and oxygen, and it is less easily absorbed by the body. It is commonly used as an antacid to treat heartburn and indigestion. While both forms of magnesium can be beneficial, the choice between them depends on the specific needs and preferences of the individual.


AttributeMagnesium CitrateMagnesium Oxide
Chemical FormulaC6H6MgO7MgO
Molar Mass214.41 g/mol40.30 g/mol
AppearanceWhite powder or granulesWhite powder
SolubilityHighly soluble in waterInsoluble in water
UsesUsed as a dietary supplement and laxativeUsed as a dietary supplement and antacid
Absorption RateHigher absorption rateLower absorption rate
Recommended DosageVaries depending on purposeVaries depending on purpose

Further Detail


Magnesium is an essential mineral that plays a crucial role in various bodily functions. It is involved in over 300 enzymatic reactions and is necessary for maintaining normal muscle and nerve function, regulating blood pressure, and supporting a healthy immune system. Magnesium supplements are commonly used to address magnesium deficiencies or as a dietary supplement to promote overall well-being. Two popular forms of magnesium supplements are magnesium citrate and magnesium oxide. In this article, we will explore and compare the attributes of these two forms to help you make an informed decision about which one may be more suitable for your needs.

1. Absorption and Bioavailability

Magnesium citrate is known for its superior absorption and bioavailability compared to magnesium oxide. When consumed, magnesium citrate dissociates into magnesium ions and citrate, which enhances its solubility and absorption in the gastrointestinal tract. This increased absorption allows for higher levels of magnesium to be delivered to the bloodstream and utilized by the body. On the other hand, magnesium oxide has a lower absorption rate due to its lower solubility. It requires a more acidic environment in the stomach for optimal absorption, which can be a limiting factor for individuals with low stomach acid levels.

Furthermore, the bioavailability of magnesium citrate is generally higher than that of magnesium oxide. Bioavailability refers to the proportion of a substance that enters the bloodstream and is available for the body to use. Magnesium citrate's higher bioavailability ensures that a larger percentage of the ingested magnesium is effectively utilized by the body, making it a preferred choice for individuals with magnesium deficiencies or those seeking to maximize their magnesium intake.

2. Bowel Regularity and Laxative Effect

Magnesium citrate is often used as a laxative due to its ability to draw water into the intestines, promoting bowel movements. It is commonly recommended for individuals experiencing occasional constipation or as a pre-procedure bowel preparation. The laxative effect of magnesium citrate can be beneficial for those seeking relief from constipation; however, it may cause loose stools or diarrhea if taken in excessive amounts.

In contrast, magnesium oxide is less likely to have a laxative effect. It is often used as a dietary supplement to support overall magnesium levels without causing significant changes in bowel regularity. This makes magnesium oxide a suitable choice for individuals who want to increase their magnesium intake without the potential side effects of loose stools or diarrhea.

3. Magnesium Content and Dosage

When comparing magnesium citrate and magnesium oxide, it is important to consider the actual magnesium content and dosage recommendations. Magnesium citrate typically contains a higher percentage of elemental magnesium compared to magnesium oxide. For example, a 500 mg magnesium citrate supplement may provide around 150 mg of elemental magnesium, while a 500 mg magnesium oxide supplement may only offer around 300 mg of elemental magnesium.

Due to the difference in elemental magnesium content, the dosage recommendations for these two forms of magnesium may vary. Individuals may need to take a higher dosage of magnesium oxide to achieve the same amount of elemental magnesium as magnesium citrate. It is crucial to follow the recommended dosage guidelines provided by the manufacturer or consult with a healthcare professional to determine the appropriate dosage for your specific needs.

4. Cost and Availability

Cost and availability are also important factors to consider when choosing between magnesium citrate and magnesium oxide. Magnesium oxide is generally more affordable and widely available compared to magnesium citrate. It is commonly found in various forms, including tablets, capsules, and powders, and can be easily purchased over-the-counter or online.

On the other hand, magnesium citrate may be slightly more expensive and less readily available. It is often found in liquid form, which can be convenient for individuals who have difficulty swallowing pills. However, the liquid form may be less convenient for travel or on-the-go use. It is worth considering your budget and personal preferences when deciding between these two forms of magnesium.

5. Potential Side Effects

Both magnesium citrate and magnesium oxide are generally safe when taken as directed. However, it is important to be aware of potential side effects that may occur, especially when consumed in excessive amounts. Common side effects of magnesium supplements include diarrhea, stomach cramps, and nausea. These side effects are more likely to occur with magnesium citrate due to its laxative effect.

Individuals with kidney problems or those taking certain medications should exercise caution when using magnesium supplements and consult with a healthcare professional before starting any new supplementation regimen. It is also important to note that excessive magnesium intake can lead to magnesium toxicity, which may cause symptoms such as irregular heartbeat, low blood pressure, and confusion. Therefore, it is crucial to follow the recommended dosage guidelines and seek medical advice if you experience any adverse effects.


In conclusion, both magnesium citrate and magnesium oxide offer their own unique attributes and benefits. Magnesium citrate provides superior absorption and bioavailability, making it an excellent choice for individuals with magnesium deficiencies or those seeking maximum magnesium utilization. However, its laxative effect may not be suitable for everyone. On the other hand, magnesium oxide is less likely to cause changes in bowel regularity and is more affordable and widely available. It can be a suitable option for individuals looking to support overall magnesium levels without the potential side effects of loose stools or diarrhea.

Ultimately, the choice between magnesium citrate and magnesium oxide depends on your specific needs, preferences, and any underlying health conditions. It is recommended to consult with a healthcare professional to determine the most appropriate form and dosage of magnesium for your individual circumstances. Remember, maintaining optimal magnesium levels is essential for overall health and well-being.

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