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Famotidine is a medication belonging to a class of drugs called H2 blockers or antagonists.

Last Modified: 17 May 2024

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What is Famotidine? 

Famotidine is a medication belonging to a class of drugs called H2 blockers or antagonists. It operates by reducing the amount of acid your stomach produces. 

Famotidine is a histamine-2 blocker with a thiazole ring that inhibits stomach acid secretion. It is synthesized chemically and designed to block the action of histamine on the H2 receptors of acid-secreting stomach cells. 

Global Name

Generic name: Famotidine 
Brand names: Pepcid, Fluxid, Topcid, Famodar 


What is Famotidine used for? 

Famotidine is used to treat and prevent: 

  • Ulcers in the stomach and intestines 
  • Gastroesophageal reflux disease (GERD) 
  • Conditions where the stomach produces too much acid, such as Zollinger-Ellison syndrome and high oxidative stress states such as major surgery, sepsis and burns 
  • Heartburn and acid indigestion 

How do you use Famotidine? 


Famotidine is available in tablet form, chewable tablets, and as an injectable solution. 

Dosage information: 

  • Adults and children over 40 kg: 20 mg to 40 mg, taken once or twice daily. 
  • Children (weighing less than 40 kg): Dosage should be determined by a healthcare provider based on weight. 


  • Children: Yes, but dosage will be adjusted based on weight. 
  • Adults: Suitable for adults. 
  • Elderlies: Suitable for elderly patients, often without dosage adjustment. 
  • Allergies: Patients with an allergy to famotidine or other H2 receptor antagonists should not take this medication. 

Is there anyone who can’t take Famotidine? 

  • Children: Not recommended for infants unless under medical supervision. 
  • Adults: Those with a known hypersensitivity to famotidine or other H2 blockers should avoid it. 
  • Elderlies: Generally safe, but may require dose adjustments based on kidney function. 
  • Pregnancy and Lactation: Should be used only if clearly needed and after consulting a healthcare provider. 
  • Allergies: Patients with an allergy to famotidine or other H2 receptor antagonists should not take this medication. 

Any warnings and precautions : 

Famotidine should be used with caution in patients with renal impairment. Patients should also be advised that famotidine does not provide immediate relief of heartburn symptoms. Long-term use of famotidine may lead to decreased absorption of vitamin B12 and iron leading to nutritional deficiency and symptoms of anemia. 

Famotidine may interact with certain drugs such as ketoconazole, itraconazole, and atazanavir, which require stomach acid to be absorbed properly. 

Side Effects

Common side effects include headache, dizziness, and constipation. Serious side effects are rare but can include an irregular heartbeat, mood changes, or seizures. 

Pharmacist Tips

When considering the use of Famotidine, it's essential to have a comprehensive understanding of how to safely incorporate this medication into your daily routine. Here are some additional tips: 
  • Medication Schedule: Establish a consistent schedule for taking Famotidine, whether it's for treatment or prevention. This helps maintain steady levels of the medication in your body. 
  • Monitoring Symptoms: Keep track of your symptoms. If you notice no improvement or if symptoms worsen, contact your healthcare provider, as this may indicate a more serious condition. 
  • Lifestyle Modifications: Along with taking Famotidine, consider lifestyle changes that can help reduce stomach acid, such as eating smaller, more frequent meals, avoiding eating before bedtime, and elevating the head of your bed. 
  • Alcohol and Smoking: Avoid alcohol and quit smoking, as both can exacerbate acid reflux and counteract the beneficial effects of Famotidine. 
  • Over-the-Counter Use: If you're using over-the-counter Famotidine, read the package instructions carefully. Do not use it for more than 14 consecutive days without medical advice. 
  • Inform Healthcare Providers: Always inform your healthcare provider and pharmacist about all the medications you are currently taking, including prescriptions, over-the-counter drugs, and herbal supplements, to avoid potential interactions. 
  • Report Side Effects: If you experience any side effects, report them to your healthcare provider, especially if they are severe or persistent. 
  • Safe Storage: Keep Famotidine out of reach of children and pets. If you suspect an overdose or accidental ingestion, seek medical attention immediately. 
  • Medication Disposal: Do not dispose of medications in wastewater or household waste. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
  • Storage Information: Store Famotidine at room temperature, away from light and moisture. Do not store in the bathroom. 
  • Handling Instructions: If using chewable tablets, chew thoroughly before swallowing. Do not swallow whole. 


Where is Famotidine available in Hong Kong?

Famotidine is an over the counter (OTC) medication that can be sold without a prescription. It is found in all chain drug stores, including Mannings and Watsons. 


How long does it take for Famotidine to work?

It may take up to an hour for Famotidine to start reducing stomach acid, with its effect lasting up to 12 hours. 

Can Famotidine be taken long-term?

Discuss long-term use with your healthcare provider, as it may mask the symptoms of more serious conditions.

Is Famotidine available for purchase over-the-counter?

Yes, lower-strength Famotidine is available over-the-counter, while higher doses require a prescription. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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