Maximum Strength Pepcid AC relieves heartburn associated with acid indigestion and sour stomach and prevents heartburn associated with acid indigestion and sour stomach brought on by eating or drinking certain food and beverages. You can take Maximum Strength Pepcid AC as little as 10 minutes before an evening with a meal*, and know you have strength on your side all day or all night**.*Prevents heartburn if taken 10 to 60 minutes before a meal.**Based on 9-hour acid control studies during the day and 12-hour acid control studies during the night. Acid control does not imply symptom relief.