Toxicology – Bromides

Core concept

Bromide intoxication (“bromism”) is an uncommon toxic syndrome caused by excessive accumulation of bromide ions, usually from chronic medicinal or supplemental exposure.

The characteristic syndrome is:

Neuropsychiatric dysfunction + ataxia/tremor + GI symptoms ± bromoderma

with a highly characteristic laboratory clue:

Pseudohyperchloremia + very low or negative anion gap

Modern reviews continue to identify this combination as one of the most useful clues to otherwise easily missed bromide toxicity.

Important distinction

Not every drug whose name contains “bromide” produces clinically significant bromide poisoning.

Bromism is most relevant to compounds that:

• Deliver substantial amounts of free bromide
• Are metabolized to bromide
• Are taken chronically or excessively

Important modern sources include:

• Potassium bromide
• Sodium bromide
• Bromovalerylurea / bromisoval
• Certain anticonvulsant or sedative preparations
• Some imported or internet-purchased medications and supplements

Bromide-containing drugs and supplements remain documented causes of modern bromism.

Bromide vs Bromine vs Bromate

These are different toxicologic entities.

Bromide

Produces bromism, primarily:

• Neurologic
• Psychiatric
• Dermatologic

Bromine gas

Produces primarily:

• Respiratory irritation
• Chemical pneumonitis
• Skin/eye injury

Bromate

Bromate compounds are strong oxidants and can cause:

• Acute kidney injury
• Hemolysis
• Severe gastrointestinal toxicity
• Sensorineural hearing loss

Therefore:

Bromide poisoning ≠ bromine gas poisoning ≠ bromate poisoning.

Pathophysiology

Bromide behaves similarly to chloride and distributes through extracellular fluid.

With excessive exposure:

Bromide accumulates → substitutes for chloride in body fluids → alters neuronal membrane function → CNS/neuropsychiatric toxicity

Bromide is eliminated mainly through the kidneys.

Its elimination is closely related to chloride handling:

Higher chloride availability → increased renal bromide clearance

This explains why saline administration can accelerate elimination.

The normal bromide elimination half-life is prolonged, reported around 10–12 days, which explains why chronic accumulation can occur.

Risk Factors

Bromism is more likely in:

• Chronic bromide use
• Renal impairment
• Older adults
• Dehydration
• High-dose therapy
• Repeated ingestion of bromide-containing medications
• Use of imported or unrecognized bromide-containing supplements

Renal dysfunction is particularly important because it decreases bromide elimination.

Acute vs Chronic Toxicity

Acute Bromide Poisoning

Acute poisoning is less common.

Large exposures may cause:

• Nausea
• Vomiting
• CNS depression
• Confusion
• Ataxia
• Coma

Severe cases may produce:

• Hypotension
• Respiratory depression

Chronic Bromide Poisoning – Bromism

Chronic toxicity is the classic presentation.

Symptoms usually evolve gradually over:

• Days
• Weeks
• Occasionally much longer

The nonspecific presentation often results in delayed diagnosis.

Clinical Features

Neurologic

Common manifestations include:

• Confusion
• Lethargy
• Weakness
• Dysarthria
• Ataxia
• Tremor
• Nystagmus
• Abnormal reflexes
• Headache

More severe toxicity may cause:

• Delirium
• Hallucinations
• Psychosis
• Severe agitation
• Stupor
• Coma

Modern reports emphasize that bromism can mimic numerous neurologic and psychiatric disorders.

Psychiatric

Possible findings include:

• Irritability
• Personality changes
• Confusion
• Emotional disturbance
• Hallucinations
• Delusions
• Acute psychosis

A new psychiatric syndrome accompanied by an unexpectedly low or negative anion gap should raise suspicion for bromide intoxication.

HEENT

Possible findings include:

• Nystagmus
• Diplopia

Occasional cranial-nerve abnormalities have been described.

Dermatologic – Bromoderma

Chronic bromide toxicity may cause bromoderma.

Typical lesions include:

• Acneiform eruptions
• Papules
• Pustules

Less commonly:

• Plaques
• Ulcers
• Bullae
• Granulomatous lesions

The face and trunk may be affected.

Gastrointestinal

Common symptoms include:

• Anorexia
• Nausea
• Vomiting
• Abdominal discomfort
• Weight loss

GI symptoms may precede obvious neurologic manifestations.

Cardiovascular

Severe acute intoxication may rarely cause:

• Tachycardia
• Hypotension

Major cardiovascular toxicity is not a typical feature of chronic bromism.

Pulmonary

Severe poisoning may rarely cause respiratory compromise.

Respiratory manifestations should also prompt consideration of:

• Coingestants
• Aspiration
• Bromine gas rather than bromide exposure

Characteristic Laboratory Finding

Pseudohyperchloremia

One of the most important clues is an apparently extremely elevated serum chloride concentration.

Bromide interferes with some chloride assays, particularly ion-selective electrode methods.

The analyzer may incorrectly interpret bromide as chloride, resulting in:

Falsely high chloride → falsely low calculated anion gap

Negative Anion Gap

The classic laboratory pattern is:

Very high measured Cl⁻ + normal or near-normal Na⁺ and bicarbonate → low or negative anion gap

For example, modern bromism cases have reported apparent chloride values above 175 mmol/L with profoundly negative calculated anion gaps.

Therefore:

Unexplained hyperchloremia + negative anion gap = think bromide or other halide interference

Important nuance

The patient usually does not truly have extreme hyperchloremia.

The correct term is:

Pseudohyperchloremia

Different laboratory analyzers have different degrees of bromide interference, so apparent chloride results can vary significantly depending on the method used.

Diagnosis

Diagnosis is based on:

Compatible exposure + neurologic/psychiatric syndrome + pseudohyperchloremia/negative anion gap + elevated serum bromide

Essential Investigations

Obtain:

• Serum electrolytes
• Chloride
• Bicarbonate
• Calculated anion gap
• BUN
• Creatinine
• Glucose

Also consider:

• Magnesium
• Calcium
• Liver function tests
• CBC

Serum Bromide Concentration

A serum bromide concentration can confirm the diagnosis.

However:

Clinical severity does not correlate perfectly with a single bromide concentration.

Historical texts commonly cite:

• Approximately 50–100 mg/dL as potentially associated with toxicity
• Higher concentrations with increasingly severe toxicity

But clinically important toxicity has occurred at varying concentrations, and modern management should be guided by both:

• Clinical condition
• Bromide concentration

A modern case reported marked neurologic toxicity with a bromide level >100 mg/dL, which resolved after discontinuation and saline therapy.

Confirming Pseudohyperchloremia

When bromism is suspected, discuss the chloride methodology with the laboratory.

Chloride may be rechecked using a method less susceptible to bromide interference.

Discordant chloride measurements between:

• Ion-selective electrode
• Alternative/colorimetric methods

can support the diagnosis.

Differential Diagnosis

Because bromism is a “great mimicker,” consider:

Toxicologic

• Lithium
• Phenytoin
• Carbamazepine
• Barbiturates
• Benzodiazepines
• Alcohol
• Other sedative-hypnotics

Neurologic

• Stroke
• Intracranial hemorrhage
• Brain tumor
• Cerebellar disease
• Encephalitis
• Meningitis

Metabolic

• Uremia
• Electrolyte abnormalities
• Hepatic encephalopathy

Psychiatric

• Acute psychosis
• Delirium from another cause

The combination of neurologic/psychiatric symptoms with a negative anion gap is especially suggestive of halide intoxication.

Treatment

1. Stop Bromide Exposure

Immediately discontinue:

• Bromide medication
• Bromide-containing supplement
• Suspected imported preparation

A careful medication history is essential.

Specifically ask about:

• OTC medications
• Foreign medications
• Herbal or dietary supplements
• Anticonvulsants
• Sedatives
• Internet-purchased preparations

2. Supportive Care

Treatment begins with:

• Airway assessment
• Respiratory support when required
• IV access
• Fluid assessment
• Correction of electrolyte abnormalities

There is no specific antidote.

Chloride / Saline Therapy

The principal enhanced-elimination strategy is chloride administration, usually with isotonic saline when clinically appropriate.

The principle is:

More chloride delivered to the kidney → increased bromide excretion

Modern literature continues to describe saline administration as a mainstay of treatment.

IV Saline

For dehydrated or symptomatic patients:

0.9% sodium chloride may be administered with careful attention to:

• Volume status
• Cardiac function
• Renal function
• Sodium
• Potassium
• Urine output

Clinical and laboratory improvement may occur rapidly once exposure is stopped and chloride delivery increases.

Avoid Uncontrolled “Forced Diuresis”

Older references recommended very high fluid rates plus routine diuretics.

Although increasing chloride delivery and urinary output enhances bromide clearance:

Aggressive forced diuresis should not be applied indiscriminately.

Potential complications include:

• Fluid overload
• Electrolyte abnormalities
• Worsening heart failure
• Further dehydration if diuretics exceed replacement

Fluid therapy should therefore be individualized.

Diuretics

Loop or thiazide diuretics have historically been used to enhance bromide elimination.

However:

Routine diuretic therapy has not been shown to improve patient-centered outcomes.

It may be considered only in selected circumstances with careful monitoring rather than as mandatory treatment.

Hemodialysis

Bromide is readily dialyzable.

Hemodialysis can dramatically accelerate bromide elimination and clinical recovery.

A published severe case found that hemodialysis shortened the bromide elimination half-life to approximately 1.4 hours and produced rapid neurologic improvement.

When to Consider Hemodialysis

Consider intermittent hemodialysis in severe bromism, particularly with:

• Significant renal impairment
• Severe encephalopathy
• Coma
• Severe neuropsychiatric toxicity
• Failure to improve with discontinuation and saline therapy
• Inability to administer sufficient chloride/fluids safely
• Very high systemic bromide burden with severe symptoms

Modern reviews identify hemodialysis as an important option for severe or refractory cases.

Why Dialysis Is Effective

Bromide:

• Is a small ion
• Has a relatively small volume of distribution
• Is largely extracellular
• Is normally cleared renally

These characteristics make extracorporeal removal effective.

Gastrointestinal Decontamination

Do Not Induce Vomiting

The historical recommendation for ipecac-induced emesis is obsolete.

Do not induce vomiting.

Gastric Lavage

Routine gastric lavage is not recommended in modern poisoning management.

It should not be performed simply because bromide ingestion occurred.

Activated Charcoal

Activated charcoal is not a central therapy for bromide ion poisoning.

Its utility depends partly on the specific formulation and any coingestants rather than on adsorption of bromide itself.

In a significant recent intentional ingestion, toxicology consultation is preferable to routine charcoal administration.

Monitoring

Symptomatic patients should have serial assessment of:

• Mental status
• Neurologic examination
• Electrolytes
• Apparent chloride
• Anion gap
• BUN
• Creatinine
• Fluid balance

When available:

• Serial serum bromide concentrations

The trend in clinical status is more important than achieving an arbitrary bromide concentration.

Admission

Hospital admission is appropriate for:

• Altered mental status
• Significant ataxia
• Psychosis or delirium
• Persistent vomiting/dehydration
• Renal insufficiency
• Severe electrolyte abnormalities
• Hypotension
• Large intentional exposure
• Need for dialysis

Severe encephalopathy or respiratory compromise warrants ICU-level care.

Prognosis

Bromism is usually reversible when recognized and treated.

Acute toxicity may improve over:

• Hours to several days

Chronic toxicity may require:

• Days to weeks for complete neurologic recovery

because bromide normally has a long elimination half-life.

Modern reports demonstrate complete neurologic recovery after bromide withdrawal and enhanced elimination.

Rarely, prolonged severe toxicity has historically been associated with persistent neurologic abnormalities such as:

• Ataxia
• Tremor
• Dysarthria
• Hyperreflexia

Pregnancy and Neonates

Bromide crosses the placenta.

Maternal chronic exposure can potentially produce neonatal bromide accumulation and CNS depression.

Significant exposure during pregnancy therefore warrants:

• Maternal assessment
• Toxicology consultation
• Appropriate fetal/obstetric monitoring according to severity

Important Pitfalls

1. Missing the negative anion gap

The classic clue is:

Pseudohyperchloremia + negative anion gap

This combination should immediately raise consideration of bromide intoxication.

2. Treating the apparent chloride value as real

A chloride concentration of 170–250 mmol/L in a clinically inconsistent setting may represent analytical interference, not true chloride excess.

3. Failing to ask about supplements or imported medicines

Modern cases continue to occur from:

• OTC medications
• Foreign medications
• Antiepileptic preparations
• Internet-purchased supplements

4. Assuming every “bromide” drug causes bromism

Many medications are formulated as bromide salts but deliver insufficient free bromide under normal use to cause classic bromism.

Exposure history must identify the actual bromide burden.

5. Confusing bromide with bromate

Bromate poisoning causes prominent renal and ototoxic injury and is a different toxicologic syndrome.

6. Confusing bromide with bromine gas

Bromine gas primarily causes:

• Pulmonary irritation
• Chemical pneumonitis
• Eye and skin injury

rather than classic bromism.

7. Overusing forced diuresis

Saline can enhance elimination, but aggressive fluid/diuretic regimens can produce:

• Volume overload
• Electrolyte disturbances

Treatment should be individualized.

8. Delaying dialysis in severe toxicity

Hemodialysis can produce rapid bromide clearance and should be considered early when severe neurologic toxicity or renal impairment is present.

High-Yield Toxicology Pearls

Bromide toxicity = bromism

Think:

Confusion/psychosis + ataxia/tremor + apparent hyperchloremia + negative anion gap

Key points:

• Chronic poisoning is more common than acute poisoning
• Bromism mainly causes neurologic and psychiatric toxicity
• Common findings: confusion, dysarthria, ataxia, tremor, nystagmus
• Dermatologic manifestation: bromoderma
• Bromide is eliminated predominantly by the kidneys
• Renal impairment and dehydration increase toxicity
• Classic laboratory clue: pseudohyperchloremia
• Bromide interferes with some chloride assays
• Result: very low or negative anion gap
• Confirm with a serum bromide concentration
• No specific antidote
• Stop the bromide-containing product
• Saline/chloride administration increases renal bromide elimination
• Routine forced diuresis is not necessary
• Hemodialysis is highly effective in severe or refractory bromism
• Ipecac and routine gastric lavage are obsolete
• Bromism is distinct from both bromine gas and bromate poisoning
• Most patients recover when the diagnosis is recognized and the exposure is stopped