What are the long term side effects of bismuth subsalicylate?

October 8, 2025 •

4 min read

While most people use bismuth subsalicylate (e.g., Pepto-Bismol) for short-term relief of gastrointestinal distress, chronic or excessive use can lead to significant and potentially severe health complications. The primary dangers of long-term ingestion revolve around the buildup of its components, bismuth and salicylate, leading to toxicity that affects the nervous system and other vital organs.

Quick Summary

Long-term or high-dose bismuth subsalicylate use risks include rare but serious neurological damage (bismuth encephalopathy) and salicylate toxicity, which can affect the central nervous system and other organs.

Key Points

Neurological Damage: Chronic, high-dose use of bismuth subsalicylate can lead to rare but serious bismuth encephalopathy, a condition affecting the brain and nervous system.
Salicylate Toxicity (Salicylism): The salicylate component, similar to aspirin, can build up in the body with long-term use, causing symptoms like tinnitus, confusion, and metabolic acidosis.
Masking Underlying Conditions: Continuous use of bismuth subsalicylate can mask the symptoms of more serious, chronic gastrointestinal diseases like ulcers or IBD.
Not for Prolonged Use: Bismuth subsalicylate is intended for short-term use (e.g., up to two days for diarrhea) and should not be used for extended periods without medical supervision.
Harmless vs. Serious Side Effects: The temporary, harmless darkening of the tongue and stool should not be confused with the serious signs of gastrointestinal bleeding or systemic toxicity.
Reye's Syndrome Risk: Due to the salicylate content, children and adolescents recovering from viral illnesses like flu or chickenpox should not take bismuth subsalicylate due to the risk of Reye's syndrome.

Bismuth subsalicylate is a popular over-the-counter (OTC) medication used to treat various gastrointestinal ailments, such as diarrhea, upset stomach, and nausea. However, this medication is designed for short-term use, typically no more than two days for diarrhea, as chronic consumption can lead to serious health problems. The long term side effects of bismuth subsalicylate stem from the accumulation of its two active components in the body: bismuth and salicylate. While toxicity from these compounds is rare with short-term, recommended use, chronic overexposure can cause debilitating and sometimes fatal conditions.

The Dual Threats of Chronic Use: Bismuth and Salicylate Toxicity

Bismuth Neurotoxicity

Although most bismuth from the subsalicylate form is poorly absorbed and excreted in stool, chronic use, especially at high doses, can lead to the slow buildup of bismuth in the body. When bismuth crosses the blood-brain barrier, it can cause a condition known as bismuth encephalopathy. This serious neurological condition is reversible upon discontinuation of the medication but can cause significant and prolonged distress.

Symptoms of bismuth encephalopathy include:

Cognitive and mood changes: Progressive confusion, memory loss, depression, anxiety, fatigue, and insomnia.
Motor impairments: Myoclonic jerks (uncontrollable, jerky muscle movements), tremors, ataxia (loss of coordination), and unsteady gait.
Other neurological issues: Dysarthria (difficulty speaking), headache, disorientation, and in severe cases, seizures.

Salicylate Poisoning (Salicylism)

The subsalicylate part of the medication is chemically related to aspirin. Salicylate is readily absorbed into the bloodstream, and like aspirin, an overdose can cause toxicity. Chronic ingestion of large doses of bismuth subsalicylate can lead to salicylism, a condition marked by several systemic symptoms. The elderly and individuals with pre-existing kidney disease are particularly vulnerable, as their bodies may have trouble eliminating the drug effectively.

Key signs of salicylism include:

Auditory issues: Persistent ringing or buzzing in the ears (tinnitus) and hearing loss.
Gastrointestinal distress: Severe nausea, vomiting, and stomach pain.
Central nervous system effects: Lethargy, confusion, agitation, and CNS dysfunction.
Metabolic changes: Patients may experience metabolic acidosis and respiratory alkalosis.

Comparison of Chronic Risks: Bismuth vs. Salicylate

To better understand the differences in toxicity from long-term use, consider the following comparison:


Feature	Bismuth Neurotoxicity	Salicylate Toxicity (Salicylism)
Cause	Accumulation of bismuth, which can cross the blood-brain barrier.	Build-up of salicylate in the bloodstream.
Primary System Affected	Central nervous system (brain, nervous system).	Auditory system (ears), GI tract, central nervous system, and metabolic processes.
Onset	Often insidious, developing gradually over months or years of chronic exposure.	Can occur more acutely with high doses, but chronic ingestion can also cause gradual onset.
Characteristic Symptoms	Myoclonic jerks, ataxia, confusion, depression, fatigue, insomnia, and speech difficulties.	Tinnitus, hearing loss, severe GI upset, rapid breathing, and metabolic imbalances.
Reversibility	Typically reversible upon discontinuation of the medication, though recovery can take weeks to months.	Symptoms generally resolve after discontinuing the medication and receiving supportive care, though some effects may linger.

Long-Term Side Effects and Recommendations

Temporary and Harmless Side Effects

It's important to distinguish the temporary, harmless side effects of bismuth subsalicylate from the serious long-term risks. A very common and expected effect is the darkening of the tongue and stool. This occurs when the bismuth component reacts with sulfur in the mouth and gastrointestinal tract to form bismuth sulfide, a black substance. This is not an indication of internal bleeding, but if experienced during chronic use, it can mask the appearance of potentially more dangerous black, tarry stools, which are a sign of gastrointestinal bleeding.

Masking an Underlying Condition

Another significant risk associated with prolonged use of bismuth subsalicylate is the potential to mask a more serious underlying gastrointestinal condition. If a person relies on this medication regularly to manage chronic stomach discomfort or diarrhea, they may be ignoring symptoms of conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), stomach ulcers, or celiac disease. It is critical to seek medical attention if symptoms persist for more than a few days.

Conclusion

While bismuth subsalicylate is a safe and effective remedy for occasional gastrointestinal upset, its long-term use carries serious risks, primarily related to bismuth and salicylate toxicity. Chronic overexposure, particularly at high doses, can lead to severe and potentially permanent neurological damage and other systemic issues. Individuals should always adhere strictly to the dosing instructions provided on the packaging and consult a healthcare professional if their symptoms persist for more than two days or worsen. The harmless side effect of a black tongue or stool should not be confused with the more dangerous signs of GI bleeding or systemic toxicity. In summary, proper use is key to enjoying the benefits of this medication while avoiding its significant long-term side effects.

This article is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any changes to your medication regimen or if you have questions about your health. For more detailed information on drug safety, you can consult reliable resources like the NCBI StatPearls database.

Frequently Asked Questions

Yes, chronic, high-dose use of bismuth subsalicylate is associated with a rare form of neurotoxicity called bismuth encephalopathy, which can cause symptoms ranging from confusion and fatigue to myoclonic jerks and seizures. The condition is usually reversible upon discontinuation of the medication, but recovery can take several months.

Bismuth toxicity, or bismuth encephalopathy, results from the accumulation of bismuth in the central nervous system and causes neurological problems like myoclonic jerks, ataxia, and cognitive issues. Salicylate toxicity (salicylism) is caused by the accumulation of salicylate in the bloodstream and primarily affects hearing (tinnitus), mental status, and metabolic balance.

With long-term use, the signs of toxicity can include progressive fatigue, confusion, anxiety, depression, insomnia, unsteady gait, memory problems, and jerky muscle movements. Tinnitus (ringing in the ears) and hearing loss can also be signs of salicylate toxicity.

The blackening of the tongue and stool from bismuth subsalicylate is a temporary and harmless side effect caused by a chemical reaction. However, long-term use can be a problem because this black color can mask serious signs of gastrointestinal bleeding, such as bloody or tarry stools.

Bismuth subsalicylate is intended for short-term use only. For the treatment of diarrhea, it should not be taken for more than two days. If symptoms persist or worsen after that period, you should stop taking it and consult a doctor.

Individuals who take large doses over extended periods, the elderly, and those with pre-existing kidney disease are at a higher risk for toxicity. Children and adolescents with a viral illness are also at risk for Reye's syndrome and should avoid the medication.

If you suspect you or someone you know is experiencing long-term side effects or has taken an overdose, stop the medication immediately and seek medical help. The signs of toxicity, especially neurological symptoms, should be evaluated by a healthcare professional.