To check for a magnesium overdose, a healthcare provider will draw your blood. Normal levels are generally around 1.8-2.3 milligrams per deciliter.

The severity of a magnesium overdose includes:

• Mild: Less than 7 milligrams per deciliter (mg/dL)
• Moderate: 7-12 mg/dL
• Severe: More than 12 mg/dL

Magnesium overdose may be overlooked initially. Checking blood magnesium levels is not that routine, and symptoms of a magnesium overdose are not unique.

Diagnosis often involves a process of elimination for other conditions like kidney failure, hypothyroidism (underactive thyroid), and high potassium levels.

The best way to boost your magnesium intake is through your diet. Magnesium-rich foods include:

• Fortified breakfast cereal
• Fruit (e.g., bananas, avocados, apples)
• Legumes (e.g., black beans, kidney beans, edamame)
• Meat (e.g., chicken breast, beef)
• Nuts and seeds (e.g., pumpkin seeds, chia seeds, almonds)
• Oatmeal
• Rice
• Seafood (e.g., salmon, halibut)
• Soy milk
• Vegetables (e.g., spinach, broccoli, carrots)

These foods have other nutrients like antioxidants and fiber that supplements do not have. Eating magnesium-rich foods also does not pose much of a risk for an overdose.

Should You Take Supplements?

Taking a magnesium supplement within the recommended daily intake is likely safe and may support overall health. Just be sure to speak with a healthcare provider about a safe dosage.

Speak with a healthcare provider before starting a supplement if you are at high risk for magnesium overdose. They may check your magnesium levels more often.

Magnesium overdose is not that common, but certain people are at higher risk.

Risk factors that increase the likelihood of an overdose include:

• Certain medications: Some medications, like anticholinergics or opioids, can increase magnesium absorption.
• Impaired kidney function: The kidneys help get rid of magnesium. Those with kidney injury or disease are more likely to get too much magnesium.
• Magnesium supplements: Taking high-dose supplements—often for constipation—makes it more likely you will overdo it. 
• Preeclampsia: This is high blood pressure during pregnancy. High doses of intravenous (IV) magnesium are used to prevent eclamptic seizures in pregnant people.

Speak with a healthcare provider if you are taking a magnesium supplement or have impaired kidney function and you have symptoms of an overdose.

Mild magnesium overdose often does not lead to symptoms. Your magnesium levels may have already progressed to a moderate overdose if you have symptoms. It is better to act early to prevent it from progressing to a severe overdose.

The treatment for magnesium overdose depends on the severity. Stopping magnesium supplements can treat a mild overdose.

Severe cases may require hospitalization to monitor your heart function and blood pressure. A doctor may administer IV calcium and saline to offset magnesium. IV diuretics or hemodialysis can get rid of magnesium faster.