Do antacids cause acidosis or alkalosis? Understanding the effects on your body's pH

October 13, 2025 •

2 min read

According to the Cleveland Clinic, occasional heartburn affects up to 60 million Americans. While antacids offer rapid relief, many people wonder: do antacids cause acidosis or alkalosis? The reality is that excessive and prolonged use can lead to the latter, causing a systemic pH imbalance called metabolic alkalosis.

Quick Summary

Excessive antacid use can lead to metabolic alkalosis, increasing the body's pH level above the normal range, especially with systemic antacids. The risk is higher for those with kidney issues. Different types of antacids, like calcium carbonate or sodium bicarbonate, have varying effects and risks.

Key Points

Antacids Cause Alkalosis: When overused, antacids can lead to metabolic alkalosis by raising the body's systemic pH, not acidosis.
Overuse is the Primary Risk Factor: Moderate, short-term antacid use is generally safe, but chronic and excessive consumption can overwhelm the body's natural pH regulation.
Systemic vs. Non-Systemic Antacids: Systemic antacids like sodium bicarbonate are more easily absorbed and carry a higher risk of metabolic alkalosis than non-systemic options like aluminum or magnesium hydroxides.
Risk Factors for Alkalosis: Individuals with impaired kidney function are particularly vulnerable to antacid-induced metabolic alkalosis.
Acid Rebound vs. Alkalosis: Some antacids, particularly calcium carbonate, can cause temporary acid rebound, but this is a separate phenomenon from the systemic metabolic alkalosis caused by overuse.
Symptoms of Alkalosis: Symptoms can include nausea, muscle twitching, tremors, dizziness, and confusion.
Adhere to Dosage: To mitigate risks, antacids should be used sparingly for occasional relief and not as a long-term treatment for chronic conditions.

The Chemistry of Antacids and Acid-Base Balance

The human body maintains a tightly regulated blood pH between 7.35 and 7.45. A pH below this range indicates acidosis, while a pH above it indicates alkalosis. Antacids contain alkaline compounds that neutralize stomach acid, such as calcium carbonate, sodium bicarbonate, or magnesium hydroxide. This neutralization raises stomach pH, providing temporary relief from heartburn.

Antacids Cause Alkalosis, Not Acidosis

Contrary to potentially causing acidosis, excessive antacid use can lead to alkalosis. While small doses primarily affect the stomach, large or frequent doses can result in the absorption of alkaline substances into the bloodstream. This influx of alkaline ions increases blood pH, resulting in metabolic alkalosis. Certain antacids and conditions like kidney failure increase this risk.

The Different Types of Antacids and Their Effects

The risk of metabolic alkalosis and other side effects varies depending on the antacid's active ingredient.

Calcium Carbonate: Fast-acting, but overuse can cause high calcium levels and metabolic alkalosis. It can also lead to acid rebound and constipation.
Sodium Bicarbonate: Provides quick relief but has high sodium content and can cause metabolic alkalosis with overuse.
Magnesium Hydroxide: Less likely to cause metabolic alkalosis in healthy individuals as it's less absorbed systemically. It can have a laxative effect.
Aluminum Hydroxide: Slow-acting and can cause constipation. Long-term use may lead to low phosphate levels. Those with kidney disease face risks from aluminum absorption.

Comparison of Common Antacid Ingredients


Ingredient	Mechanism of Action	Primary Side Effects	Risk of Metabolic Alkalosis	Primary Drug Interactions
Calcium Carbonate	Rapid, potent neutralization	Constipation, acid rebound, hypercalcemia	Moderate to High (with overuse)	Reduced absorption of iron, zinc, some antibiotics
Sodium Bicarbonate	Rapid, short-acting neutralization	High sodium load, belching	High (with overuse)	Reduced absorption of acidic drugs, altered excretion of others
Magnesium Hydroxide	Neutralization, also a laxative	Diarrhea, electrolyte imbalance	Low (in healthy individuals)	Reduced absorption of iron, zinc, some antibiotics
Aluminum Hydroxide	Slow, sustained neutralization	Constipation, hypophosphatemia	Low (in healthy individuals)	Reduced absorption of iron, zinc, some antibiotics

Understanding and Managing the Risks

Chronic excessive antacid use, particularly systemic types, poses a significant risk of metabolic alkalosis. Symptoms can include nausea, muscle twitching, tremors, dizziness, and confusion. Individuals with kidney problems are more susceptible. Acid rebound is a separate issue that affects stomach acidity but not systemic pH. To minimize risks, use antacids only occasionally as directed. Persistent heartburn requires medical evaluation to address the underlying cause.

Conclusion

In conclusion, overuse of antacids leads to alkalosis, not acidosis, by increasing systemic pH. The risk of metabolic alkalosis is higher with systemic antacids like sodium bicarbonate. While useful for occasional heartburn, chronic use requires consulting a healthcare professional for proper diagnosis and treatment to avoid complications from pH imbalance. Always follow dosage instructions.

International Foundation for Gastrointestinal Disorders (IFFGD)

Frequently Asked Questions

Metabolic alkalosis is a medical condition where the body's pH level becomes too alkaline (basic), rising above 7.45. It can be caused by various factors, including the excessive intake of antacids, especially those containing systemic ingredients like sodium bicarbonate.

Symptoms of metabolic alkalosis can range from mild to severe and include nausea, muscle twitching, hand tremors, dizziness, confusion, and difficulty breathing.

No, antacids do not cause acidosis. They are alkaline substances that neutralize acid. Excessive use leads to the opposite condition, which is metabolic alkalosis.

Yes. Systemic antacids, such as those with sodium bicarbonate, are more easily absorbed into the bloodstream and carry a higher risk of causing metabolic alkalosis. Non-systemic antacids like magnesium and aluminum hydroxides are less likely to cause a systemic pH change in healthy individuals.

Acid rebound is a phenomenon where the stomach produces more acid to compensate after it has been neutralized, particularly with calcium carbonate antacids. This can worsen heartburn but is a temporary effect in the stomach and does not cause systemic acidosis.

Individuals with impaired kidney function are at a higher risk because their kidneys cannot effectively excretethe excess alkali from the antacids. Chronic or excessive users of systemic antacids are also at increased risk.

To prevent metabolic alkalosis, use antacids only as directed for short-term relief and do not exceed the recommended dosage. If you experience chronic or frequent heartburn, consult a healthcare provider to find and address the root cause.

Yes, antacids can interfere with the absorption of many other medications by altering stomach pH. It is generally recommended to take other medications at least two to four hours apart from antacids to avoid interactions.