Magnesium vs Selenium — Which Should You Take?
Magnesium supports hundreds of enzymatic processes. Selenium specifically supports thyroid function and antioxidant enzymes. Magnesium is more commonly deficient and addresses more symptoms.
Quick Verdict
Magnesium for broader health; selenium for thyroid specifically
Magnesium Benefits
Selenium Benefits
Magnesium Side Effects
Selenium Side Effects
Can You Take Magnesium and Selenium Together?
In most cases, Magnesium and Selenium can be taken together safely. However, always check the interactions section of each supplement and consult a healthcare professional if you take medication or have existing health conditions.
Magnesium: May reduce absorption of antibiotics (tetracyclines, quinolones)
Magnesium: Can interact with blood pressure medications
Selenium: May reduce effectiveness of certain chemotherapy agents
Selenium: Synergistic antioxidant effects with vitamins C and E
Which Should You Choose?
Magnesium for broader health; selenium for thyroid specifically. Many people take both as they target different aspects of health. The best choice depends on your individual needs, existing diet, and health goals. If in doubt, start with one, assess for 4-8 weeks, then consider adding the other.
Affiliate links — we may earn a small commission at no extra cost to you.
Frequently Asked Questions
Is Magnesium better than Selenium?
Magnesium for broader health; selenium for thyroid specifically
Can I take Magnesium and Selenium together?
In most cases, yes. Magnesium and Selenium can be taken together safely. However, always check for specific interactions and consult a healthcare professional if you take medication.
What is the best time to take Magnesium?
Evening for sleep benefits, split doses for absorption
What is the best time to take Selenium?
With meals to enhance absorption; consistent daily timing
What are the side effects of Magnesium?
Loose stools (especially citrate/oxide forms). Rare: low blood pressure at very high doses. Generally very safe.
What are the side effects of Selenium?
Selenosis (toxicity) at excessive doses: garlic odour on breath, brittle nails, hair loss. Gastrointestinal upset at high doses. Tremors and neurological effects with severe overdose.
How We Compare Supplements
This comparison is based on published clinical research, peer-reviewed studies from PubMed, and established nutritional science. We evaluate dosages based on clinically-effective amounts, not manufacturer recommendations. Benefits listed have at least moderate evidence from human studies. When evidence is limited or conflicting, we note this.