Patients who take antacids should consult their physicians before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

Certain medications are known to interact poorly with antacids. For example, use of antacids with the antibiotic tetracycline can decrease the effects of both medicines. Other medications that may interact poorly with antacids and cause one or both medicines to be ineffective include:

• Cellulose sodium phosphate (medicine used to prevent formation of calcium-containing kidney stones)
  
  
• Fluoroquinolones (medication used to treat bacterial infections)
  
  
• Isoniazid (medication used to treat or prevent tuberculosis)
  
  
• Ketoconazole (medication used to treat fungal infections)
  
  
• Methenamine (antibiotic used to treat urinary tract infections)
  
  
• Mecamylamine (antihypertensive used to treat high blood pressure)