Atenolol and Magnesium Carbonate: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Atenolol
Magnesium Carbonate
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Atenolol (Tenormin) is a beta blocker that helps lower your blood pressure and slow a fast heartbeat. Magnesium carbonate is found in many antacids and supplements. When you take them at the same time, the magnesium can grab onto the atenolol in your stomach and keep your body from soaking it up fully. That means less atenolol gets into your blood, so it may not work as well.
The good news is this is easy to handle. You don't have to stop either one. Usually it just comes down to spacing them apart during the day. Your pharmacist or doctor can help you set up a simple schedule that keeps both working.
Effect: Reduced atenolol efficacy via decreased GI absorption when co-administered with magnesium carbonate (a polyvalent-cation antacid). Neither agent is metabolically activated, so this is a purely PK, absorption-level interaction reducing atenolol bioavailability and exposure (AUC).
- Direction: Reduced atenolol effect (lower BP/HR control).
- Onset: Rapid.
- Evidence: Probable; severity minor.
- Management: Separate administration. Give atenolol 2 hours before or 6 hours after the magnesium product. Monitor blood pressure and heart rate; if control appears inadequate, reassess timing and dose with the care team.
What happens
Reduced effectiveness of atenolol
Interaction Deep Dive
Research indicates that taking atenolol together with products that contain aluminum, calcium, or magnesium can lower the bioavailability of atenolol and may diminish how well it works21.
Why it happens (mechanism)
Decreased atenolol absorption
How to manage this interaction
This is a timing interaction, and it is very manageable. Keep taking both medications as prescribed.
- Space them out. Take your atenolol at least 2 hours before, or 6 hours after, any magnesium carbonate product (including many antacids).
- Watch how you feel. Your care team may check your blood pressure or heart rate to confirm the atenolol is still working well.
- Ask before adding antacids or supplements. Tell your pharmacist about any over-the-counter products with magnesium, calcium, or aluminum.
If your dose ever needs fine-tuning, that can be individualized by your care team.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Taking atenolol together with calcium carbonate has been reported to cause a marked reduction in peak plasma atenolol concentrations (by 51%) after single doses. During extended concurrent use, the atenolol half-life rose from 6.2 hours to 11 hours, which partly offset the lower plasma levels. Hemodynamic measurements were comparable after 4 weeks of combined use. Dosage modification does not appear to be required in patients on long-term atenolol and calcium therapy. Patients with severe coronary heart disease should be given double the usual atenolol dose on the first day of calcium therapy 1.
b) Six healthy male volunteers fasted for ten hours and were subsequently administered atenolol 100 mg along with 30 mL of an antacid containing aluminum hydroxide, magnesium hydroxide, and magnesium carbonate. The systemic bioavailability of atenolol fell by an average of 33%, and the maximum plasma concentration dropped by 37%. These findings indicate that the absorption of atenolol, which is normally 50% absorbed in the gut, may be lowered sufficiently with concurrent antacid use to produce a decrease in therapeutic efficacy 2.
Common questions
Can I take Atenolol and Magnesium Carbonate together?
Magnesium carbonate can reduce how much atenolol your body absorbs, so take atenolol 2 hours before or 6 hours after the magnesium product to keep it working. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atenolol and Magnesium Carbonate interaction?
It is rated minor. Usually limited clinical impact.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Atenolol and Magnesium Carbonate interaction managed?
This is a timing interaction, and it is very manageable. Keep taking both medications as prescribed. Space them out. Take your atenolol at least 2 hours before, or 6 hours after, any magnesium carbonate product (including many antacids). Watch how you feel. Your care team may check your blood pressure or heart rate to confirm the atenolol is still working well. Ask before adding antacids or supple… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Atenolol or Magnesium Carbonate need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Kirch W, Schafer-Korting M, Axthelm T, et al: Interaction of atenolol with furosemide and calcium and aluminum salts. Clin Pharmacol Ther 1981; 30:429-435. PubMed
- Regardh CG, Lundborg P, & Persson BA: The effect of antacid, metoclopramide and propantheline on the bioavailability of metoprolol and atenolol. Biopharm Drug Dispos 1981; 2:79-87. DOI
Keep reading about Atenolol
Keep reading about Magnesium Carbonate
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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