SIDE EFFECTS: Headache, constipation or diarrhea may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. If your doctor has directed you to use this medication, remember that he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: easy bruising/bleeding, fast/slow/irregular heartbeat, signs of infection (such as sore throat that doesn't go away, fever, chills), mental/mood changes (e.g., restlessness, confusion, depression, hallucinations), seizure. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking famotidine, tell your doctor or pharmacist if you are allergic to it; or to other H2 blockers (e.g., cimetidine, ranitidine); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. If you have any of the following health problems, consult your doctor or pharmacist before using this medication: kidney problems, liver problems, other stomach problems (e.g., tumors). Some symptoms may actually be signs of a more serious condition. Get medical help right away if you have: heartburn with lightheadedness/sweating/dizziness, chest/jaw/arm/shoulder pain (especially with shortness of breath, unusual sweating), unexplained weight loss. In addition, before you self-treat with this medication, get medical help right away if you have any of these signs of a serious condition: trouble/pain swallowing food, bloody vomit, vomit that looks like coffee grounds, bloody/black stools, heartburn for over 3 months, frequent chest pain, frequent wheezing (especially with heartburn), nausea/vomiting, stomach pain. This chewable form of this medication contains aspartame. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist regarding the safe use of this medication. Do not use this medication in children younger than 12 unless directed by the doctor. Older adults may be more sensitive to the side effects of this drug, especially confusion. During pregnancy, this medication should only be used if clearly needed. Discuss the risks and benefits with your doctor. Tell your doctor if you are pregnant before using this medication. This drug passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products need stomach acid so that the body can absorb them properly. Famotidine decreases stomach acid, so it may change how well these products work. Some affected products include atazanavir, dasatinib, delavirdine, certain azole antifungals (such as itraconazole, ketoconazole), pazopanib, among others. Do not take this medication with other products that contain famotidine or other H2 blockers (cimetidine, nizatidine, ranitidine).

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.