Does Famotidine Affect Memory? Understanding the Cognitive Side Effects

October 6, 2025 •

3 min read

According to the FDA, famotidine is associated with potential central nervous system adverse reactions, including confusion and delirium. However, recent studies and case reports present conflicting evidence on whether famotidine affects memory, especially concerning long-term use and its potential for both harm and benefit in specific conditions.

Quick Summary

Famotidine can cause short-term cognitive side effects like confusion and disorientation, particularly in vulnerable populations. The evidence linking it to long-term memory impairment or dementia is inconsistent, with some studies showing an association while others find no risk. Intriguingly, it has also been investigated for improving COVID-19-related brain fog.

Key Points

FDA Warning: The FDA label for famotidine lists potential central nervous system (CNS) adverse reactions, including confusion, delirium, and disorientation.
At-Risk Populations: Elderly patients and individuals with kidney or liver impairment are particularly susceptible to the cognitive side effects of famotidine.
Conflicting Dementia Evidence: The link between long-term famotidine or other H2 receptor antagonist use and dementia risk is inconsistent across studies, with some finding no association while others suggest a risk in those with pre-existing cognitive issues.
Potential for Cognitive Benefit: Some research indicates that famotidine may help improve cognitive impairment in patients with post-COVID-19 brain fog, possibly by reducing inflammation.
Consult a Professional: If you experience memory issues or confusion while taking famotidine, it is crucial to consult your doctor to evaluate the cause and consider alternative treatments.
Reversible Symptoms: In reported cases, cognitive side effects associated with famotidine are often reversible upon discontinuation of the medication.

The Conflicting Evidence on Famotidine and Memory

Famotidine (brand name Pepcid) is an H2 receptor antagonist used for conditions involving excess stomach acid. While generally safe, its impact on memory is debated, with research showing conflicting results regarding short-term cognitive issues, long-term dementia risk, and even potential cognitive benefits.

Documented Cognitive Side Effects

Cognitive side effects are rare but known, especially in certain patients. The FDA lists central nervous system (CNS) adverse reactions for famotidine.

Potential CNS effects include:

Confusion
Delirium
Hallucinations
Disorientation
Agitation
Seizures
Unusual drowsiness or lethargy

These effects are more common in elderly patients and those with kidney or liver issues. Case reports describe reversible mental changes in elderly patients after taking famotidine. Discontinuing the medication usually resolves these symptoms.

The Role of Histamine in the Brain

Famotidine blocks H2 receptors, found in both the stomach and brain. Histamine in the brain affects sleep-wake cycles, attention, and memory. By blocking H2 receptors, famotidine can interfere with these processes, potentially causing cognitive issues.

Famotidine's Potential Positive Effect on Brain Fog

Studies suggest famotidine may help improve cognitive function in post-COVID-19 brain fog and mast cell activation syndrome (MCAS). It is thought that famotidine's anti-inflammatory properties might play a role in reducing inflammation associated with brain fog.

Comparison of Cognitive Effects: Famotidine vs. Other Medications


Feature	Famotidine (H2 Receptor Antagonist)	Proton Pump Inhibitors (PPIs)	Anticholinergic Medications
Mechanism of Action	Blocks H2 receptors, reducing stomach acid and affecting brain receptors.	Blocks proton pumps that produce stomach acid.	Blocks acetylcholine, a key neurotransmitter for memory.
Potential Cognitive Effects	Can cause short-term confusion and delirium, especially in vulnerable individuals.	Conflicting evidence on long-term effects; may be linked to B12 deficiency.	Strongly associated with short- and long-term memory loss and confusion.
Dementia Risk	Mixed observational study results; some suggest a link in those with pre-existing cognitive issues, others find no association.	Some studies link long-term use to higher risk, but clinical trials are often inconclusive.	Established link with accelerated cognitive decline and increased dementia risk with long-term use.
Vulnerable Populations	Elderly and those with kidney or liver problems are most susceptible to CNS side effects.	Risk may be related to other health conditions and multiple medications in older adults.	Elderly are particularly vulnerable due to increased sensitivity and changes in the blood-brain barrier.

Factors That Increase the Risk of Cognitive Side Effects

Certain factors increase the likelihood of experiencing famotidine's cognitive effects:

Age: Older adults are more vulnerable due to altered drug processing and increased blood-brain barrier permeability.
Renal or Hepatic Impairment: Kidney or liver issues can lead to higher drug levels, increasing side effect risk.
Dosage: Higher doses, particularly intravenous ones, are more likely to cause mental changes.
Drug-Drug Interactions: Using famotidine with other medications, especially anticholinergics, can increase cognitive impairment risk.

Conclusion: Balancing Risks and Benefits

Famotidine's effect on memory is not fully understood, though generally safe for short-term use. Vulnerable populations, such as the elderly or those with kidney issues, have a higher risk of acute confusion or delirium. Conflicting study results mean the link to long-term dementia risk is uncertain. Research into its potential to help post-COVID-19 brain fog adds complexity. Consult a doctor if cognitive changes occur while taking famotidine.

For detailed information on side effects, refer to {Link: Mayo Clinic https://www.mayoclinic.org/drugs-supplements/famotidine-oral-route/description/drg-20072972}.

Frequently Asked Questions

While it doesn't cause a typical form of short-term memory loss, famotidine can cause acute mental status changes like confusion and disorientation, which can interfere with attention and recall. These effects are more common in vulnerable populations, such as the elderly, especially with underlying kidney or liver issues.

Yes, elderly patients are at higher risk. Age-related changes in metabolism, reduced kidney function, and increased blood-brain barrier permeability can lead to higher famotidine levels in the bloodstream, increasing the risk of adverse CNS reactions like confusion and delirium.

Famotidine is an H2 receptor antagonist. Since H2 receptors are present in the brain, blocking them can interfere with the normal function of histamine as a neurotransmitter, which plays a role in cognitive processes like attention and memory.

The evidence on a link between long-term famotidine (or H2RA) use and dementia is inconsistent. Some observational studies suggest an association, particularly in individuals with pre-existing mild cognitive impairment, while other robust studies, controlling for confounding factors, have found no association with long-term use in older adults.

Yes, confusion, disorientation, and delirium are known adverse effects of famotidine, particularly in vulnerable patients. Case reports have documented reversible mental status changes in elderly patients treated with famotidine, with symptoms resolving after the medication was stopped.

You should not stop any medication without consulting a healthcare professional. If you experience cognitive issues, inform your doctor. They can determine if famotidine is the cause and, if so, suggest dosage adjustments or alternative treatments.

No, the effect varies significantly. Most people do not experience cognitive side effects from famotidine. The risk is highest for specific vulnerable populations, such as the elderly, those with kidney or liver problems, and possibly those with pre-existing cognitive impairment.