What vitamins should you not take with antacids? A guide to preventing nutrient deficiencies

October 10, 2025 •

4 min read

Did you know that long-term use of acid-reducing medications, including antacids, is linked to an increased risk of vitamin B12 deficiency? Understanding what vitamins should you not take with antacids can prevent these potentially serious complications and ensure your supplements work effectively.

Quick Summary

Antacids interfere with vitamin and mineral absorption by altering stomach acid levels or directly binding with nutrients. This can lead to deficiencies in essential vitamins like C, B12, and D, as well as minerals such as iron and zinc. Timing your supplements correctly is crucial to avoid these negative interactions.

Key Points

Check Antacid Ingredients: Certain vitamins, like C and D, interact specifically with aluminum-containing antacids, which can increase aluminum absorption to toxic levels.
Watch Vitamin B12: Long-term use of antacids can significantly reduce stomach acid, impairing the absorption of vitamin B12.
Separate Iron Supplements: Calcium carbonate antacids can compete with iron for absorption, making it crucial to space out your iron and antacid intake.
Time Folic Acid Carefully: Folic acid supplements can be less effective if taken too close to antacids, so separate their doses by a couple of hours.
Beware Mineral Competition: Other minerals like zinc can also have their absorption reduced by calcium-containing antacids.
Maintain Timing for Safety: A general rule is to take vitamins and minerals at least two hours before or after your antacid dose to minimize interactions.

How Antacids Affect Nutrient Absorption

Antacids are a widely used, over-the-counter treatment for heartburn and indigestion. They work by neutralizing stomach acid, which can disrupt the normal process of nutrient absorption. Some minerals and vitamins require an acidic environment to be properly absorbed by the body. When antacids reduce this acidity, they can prevent your body from getting the full benefit of certain nutrients from food and supplements.

Additionally, some ingredients in antacids can directly bind to vitamins and minerals, forming complexes that the body cannot absorb. Therefore, the specific ingredients in your antacid matter when considering potential interactions with your vitamin regimen.

Vitamins and Minerals to Watch for with Antacids

Vitamin B12 (Cobalamin)

Stomach acid is essential for releasing vitamin B12 from the food proteins it's bound to, a critical step for absorption. Antacids, especially proton pump inhibitors (PPIs) and H2 blockers, significantly reduce stomach acid, making it difficult for the body to absorb B12 effectively.

Interaction: Decreased absorption due to reduced stomach acidity.
Risk: Long-term use of acid-suppressing medications increases the risk of B12 deficiency, which can cause anemia and neurological issues.
Action: If taking antacids long-term, consult a doctor about monitoring B12 levels. Separate supplements by several hours.

Vitamin C and Aluminum-Containing Antacids

Some antacids, such as Mylanta and Gaviscon, contain aluminum hydroxide. While generally safe, this ingredient can pose a risk when taken alongside high-dose vitamin C supplements.

Interaction: Vitamin C increases the body's absorption of aluminum from the antacid, which can lead to aluminum toxicity.
Risk: Aluminum toxicity is a particular concern for individuals with kidney problems and can cause weakness and confusion.
Action: If taking an aluminum-based antacid, separate your vitamin C supplement by at least two to four hours.

Vitamin D and Aluminum-Containing Antacids

Vitamin D's primary role is to help the body absorb calcium, but it can also increase the absorption of other substances, including aluminum.

Interaction: When taken with aluminum-containing antacids, vitamin D can promote the absorption of aluminum into the body.
Risk: Elevated aluminum levels can be harmful, especially for individuals with kidney disease.
Action: Avoid taking vitamin D supplements at the same time as antacids containing aluminum.

Folic Acid (Vitamin B9)

Antacids that alter gastric pH can impair the absorption of synthetic folic acid found in supplements.

Interaction: Reduced absorption due to a less acidic environment.
Risk: Although the effect may be small, it can be a concern for those with low dietary intake of folate or long-term antacid use.
Action: Take your folic acid supplement at least two hours before or after your antacid dose.

Mineral Interactions Caused by Antacids

Beyond vitamins, several key minerals can also be affected by antacid use.

Iron

Iron absorption, particularly non-heme iron from plant-based foods and most supplements, relies heavily on stomach acid.

Interaction: Antacids neutralize stomach acid, which reduces iron solubility and intestinal absorption. Calcium carbonate antacids can also compete with iron for absorption.
Risk: Decreased iron absorption can contribute to iron-deficiency anemia, especially in at-risk individuals like pregnant women.
Action: Take iron supplements at least two hours before or after any antacid containing calcium or aluminum.

Zinc

Like iron, zinc absorption can be negatively affected by the competitive binding with calcium in antacids.

Interaction: Calcium in antacids can substantially decrease zinc absorption when taken at the same time.
Risk: While a meal can mitigate some effects, chronic high-calcium intake from antacids can reduce zinc levels.
Action: Separate your zinc supplement from calcium-containing antacids by at least two hours.

Magnesium

While many antacids contain magnesium, chronic use of aluminum-based antacids can lead to magnesium depletion by increasing its excretion. Conversely, in individuals with impaired kidney function, magnesium-containing antacids can lead to hypermagnesemia (excessive magnesium levels).

Interaction: Aluminum-based antacids can deplete magnesium, while kidney patients can accumulate too much magnesium from antacids that contain it.
Risk: Can lead to bone problems or toxicity in kidney patients.
Action: Patients with kidney issues should always consult a doctor before taking magnesium-containing products.

Timing Your Supplements and Antacids: A Comparison


Antacid Type	Interacting Vitamin/Mineral	Potential Issue	Recommended Timing	Reference
Aluminum-Containing	Vitamin C	Increased aluminum absorption and toxicity.	Take vitamin C 2-4 hours before or after antacid.
Aluminum-Containing	Vitamin D	Increased aluminum absorption.	Separate by 2-4 hours.
Calcium Carbonate	Iron (non-heme)	Competitive absorption; reduced iron absorption.	Take iron 2 hours before or after antacid.
Calcium Carbonate	Zinc	Competitive absorption; reduced zinc absorption.	Take zinc 2 hours before or after antacid.
All Antacids	Vitamin B12	Reduced absorption due to lower stomach acid.	Separate supplements by several hours; long-term users may need injections.
Aluminum/Magnesium Antacids	Folic Acid	Slight impairment of synthetic folic acid absorption.	Take folic acid 2 hours before or after antacid.

Conclusion

While antacids are a safe and effective remedy for occasional heartburn, they can have significant interactions with vitamins and minerals, especially with long-term use. By understanding how different antacid ingredients can affect nutrient absorption, you can take steps to prevent deficiencies. The key takeaway is to time your supplements strategically, separating them from your antacid dose by at least two to four hours. For long-term antacid use, particularly with acid-suppressing medications, it is wise to consult your doctor about monitoring nutrient levels. Always read the labels of both your antacids and supplements, and when in doubt, speak to a healthcare professional for personalized guidance.

Learn more about potential drug-nutrient interactions from authoritative sources, such as the Linus Pauling Institute.

Frequently Asked Questions

No, it is not recommended to take a multivitamin at the same time as an antacid. Many multivitamins contain minerals like iron and zinc that can have their absorption reduced by antacids. It's best to separate them by at least two hours.

Some common brand names of antacids that contain aluminum include Mylanta, Gaviscon, Maalox, and Gelusil. Always check the active ingredients list on the packaging to be certain.

Taking vitamin C with an aluminum-containing antacid can increase the body's absorption of aluminum, potentially leading to aluminum toxicity. This is especially risky for individuals with impaired kidney function.

Stomach acid is needed to release vitamin B12 from food. Antacids, which reduce stomach acid, can hinder this process and prevent proper B12 absorption, leading to potential deficiency, particularly with long-term use.

Yes. The calcium in Tums can compete with non-heme iron (the form found in most supplements) for absorption. It is best to take iron supplements at least two hours apart from Tums to minimize this effect.

It is not recommended. Individuals with kidney disease have a reduced ability to clear magnesium, and taking magnesium-containing antacids can lead to excessively high magnesium blood levels. Consult a doctor for safer alternatives.

The best practice is to separate your vitamin and antacid doses. Take your vitamin or mineral supplements at least two to four hours apart from your antacid. You can also talk to your pharmacist about the best timing for your specific medications and supplements.