2. People with Kidney Disease or Reduced Kidney Function
This is an especially important precaution. Healthy kidneys remove excess magnesium from the body. If kidney function is reduced, magnesium can build up in the bloodstream and cause hypermagnesemia, a potentially serious condition.
Symptoms of excessive magnesium may include:
- Nausea and vomiting
- Low blood pressure
- Muscle weakness
- Drowsiness
- Confusion
- Irregular heartbeat
- Difficulty breathing
If you have kidney disease, do not take magnesium supplements unless your healthcare provider recommends and monitors their use.
Magnesium can interact with more than prescription medications, so the supplements you take alongside it also deserve careful consideration.
Other Important Considerations
If You Take Other Supplements
Magnesium can also interact with other minerals, including:
- Calcium: High doses may compete for absorption.
- Zinc: Very large doses may reduce magnesium absorption.
- Iron: Taking magnesium and iron together may reduce the absorption of both.
Consider separating these supplements by at least two hours unless your healthcare provider advises otherwise.
During Pregnancy or Breastfeeding
Magnesium is generally considered safe when taken in recommended amounts. However, high supplemental doses may not be appropriate for everyone. Consult your healthcare provider before taking magnesium supplements during pregnancy or breastfeeding.
If You Have Heart Disease
Because magnesium can affect heart rhythm and blood pressure, discuss supplementation with your cardiologist or healthcare provider before starting a supplement.
How to Take Magnesium Safely
Timing Matters
If you take medications that interact with magnesium, the appropriate separation period can vary by medication. Follow your pharmacist’s or healthcare provider’s instructions rather than relying on a single timing rule for every drug.
Taking magnesium with food may help reduce stomach upset.
Start with a Low Dose
For adults, the appropriate supplemental dose depends on individual needs, the form of magnesium, and dietary intake. Do not increase the dose simply because a higher amount is advertised as more effective. Follow the product directions or your healthcare provider’s recommendation.
Choose the Right Form
| Form | Common Uses | Notes |
|---|---|---|
| Magnesium glycinate | Supplementation and relaxation | Generally well tolerated |
| Magnesium citrate | Constipation | May cause loose stools |
| Magnesium oxide | General supplementation | Less readily absorbed than some other forms |
| Magnesium malate | General supplementation | Absorption and tolerance vary between individuals |
| Magnesium chloride | General supplementation | Generally well absorbed |
Consider Testing
Before assuming you need a supplement, it helps to understand what testing can—and cannot—tell you about your magnesium status.
If your healthcare provider suspects a deficiency, they may recommend laboratory testing. Although magnesium deficiency can occur, routine blood magnesium testing does not always reflect the body’s total magnesium stores.
Possible Signs of Magnesium Deficiency
Symptoms that may be associated with magnesium deficiency include:
- Muscle cramps or twitching
- Fatigue
- Poor sleep
- Anxiety
- Headaches
- Constipation
- Irregular heartbeat
These symptoms are not specific to magnesium deficiency and can have many other causes. A healthcare professional can help determine the underlying reason.
Food Sources of Magnesium
Many people can meet their magnesium needs through a balanced diet.
| Food | Approximate Magnesium per Serving |
|---|---|
| Pumpkin seeds (1 ounce) | 150 mg |
| Almonds (1 ounce) | 80 mg |
| Cooked spinach (1 cup) | 80 mg |
| Black beans (1 cup) | 60 mg |
| Avocado (1 medium) | 45 mg |
| Dark chocolate (1 ounce) | 65 mg |
| Banana (1 medium) | 30 mg |
Safe Intake Guidance
- Healthy adults: The tolerable upper intake level for magnesium from supplements and medications is 350 mg per day unless prescribed by a healthcare provider. Magnesium from food is not included in this limit.
- People with kidney disease: Use magnesium supplements only under medical supervision.
- Older adults: Individual needs vary; consult a healthcare provider before taking high-dose supplements.
Knowing when to stop a supplement is just as important as knowing how to start one, especially if concerning symptoms appear.
When to Stop Taking Magnesium and Seek Medical Advice
Stop taking magnesium supplements and contact your healthcare provider if you experience:
- Severe diarrhea
- Low blood pressure
- Confusion
- Significant muscle weakness
- Irregular heartbeat
- Difficulty breathing
The Bottom Line
Magnesium is an essential mineral that supports many important body functions, but supplements are not appropriate for everyone. Extra caution is recommended for:
- People taking medications that may interact with magnesium.
- People with kidney disease or reduced kidney function.
If you are considering magnesium supplements:
- Talk with your healthcare provider first.
- Choose the most appropriate form for your needs.
- Separate magnesium from interacting medications according to professional guidance.
- Follow the recommended dosage and watch for side effects.
A healthcare professional can help determine whether magnesium supplementation is appropriate for your individual health needs.
