Before taking famotidine, tell your doctor or pharmacist if you are allergic to it; or to other H2 blockers (such as 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.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: immune system problems, kidney problems, liver problems, lung problems (such as asthma, chronic obstructive pulmonary disease-COPD), other stomach problems (such as 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.

Do not use to treat children younger than 12 unless directed by the doctor.

Older adults may be more sensitive to the side effects of this drug, especially mental/mood changes (such as confusion), seizure, or unusual tiredness.

During pregnancy, famotidine should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk. Consult your doctor before breastfeeding.