Stop use and ask a doctor if: your heartburn continues or worsens, you need to take this product for more than 14 days. Do not use: if you have trouble or pain swallowing food, vomiting with blood, or bloody or black stools. These may be signs of a serious condition. See your doctor. With other acid reducers. Allergy alert: do not use if you are allergic to famotidine or other acid reducers. Ask a doctor before use if you have: had heartburn over 3 months. This may be a sign of a more serious condition. Heartburn with lightheadedness, sweating, or dizziness, chest pain or shoulder pain with shortness of breath; Sweating; Pain spreading to arms, neck or shoulders; Or lightheadedness, frequent chest pain, frequent wheezing, particularly with heartburn, unexplained weight loss, nausea or vomiting, stomach pain. Ask a doctor or pharmacist before use if you: are presently taking a prescription drug. Antacids may interact with certain prescription drugs. If pregnant or breast-feeding, ask a health professional before use. Keep out of reach of children. In case of overdose, get medical help or contact a poison control center right away.