II. Epidemiology

  1. U.S.: 1000 to 5000 Poisoning per year

III. Pathophysiology

  1. Methanol is a common industrial and household solvent (paint remover) and fuel additive
    1. Antifreeze
    2. Perfume
    3. Pain solvents
    4. Paints, Varnishes and Shellacs
    5. Windshield washing fluid
    6. Carburetor cleaner
    7. Fracking Fluid
    8. Adhesives
  2. Mechanisms of ingestion
    1. Accidental Ingestion by children
    2. Industrial workers may inhale Methanol vapors (e.g. formaldehyde production, shellac processing)
    3. Alcoholism with Methanol ingestion when Alcohol unavailable
    4. Bootleg Alcohol (especially in developing nations, and where outlawed in conservative countries)
      1. In 2018, >150 deaths were reported due to Methanol-laced counterfeit liquor
      2. In the 1920s during U.S. prohibition, industrial Alcohols were mandated to be laced with Methanol
  3. Methanol is quickly absorbed by the Gastrointestinal Tract
    1. Serum levels peak within 60-90 minutes of ingestion
  4. Hepatic Metabolism
    1. Methanol is metabolized into Formaldehyde (via Alcohol dehydrogenase)
    2. Formaldehyde is metabolized into Formic Acid (via aldehyde dehydrogenase)
    3. Formic acid is the primary toxin resulting in most of the ingestion-related damage and Metabolic Acidosis
    4. Formic acid is very slowly metabolized into carbon dioxide and water (via Tetrahydrofolate)

IV. Symptoms

  1. Symptom onset is delayed 12-24 hours from ingestion
    1. Related to delay in metabolism to formic acid
  2. Neurologic
    1. Headache
    2. Altered Level of Consciousness and Intoxication
    3. Seizure
    4. Extrapyramidal symptoms
    5. Parkinsonism
    6. Paresthesias
    7. Tinnitus (from Ototoxicity)
  3. Cardiopulmonary
    1. Dyspnea
    2. Tachypnea
    3. Kussmaul Respirations (due to Metabolic Acidosis)
    4. Hypotension (or Hypertension)
    5. Bradycardia
  4. Gastrointestinal
    1. Nausea or Vomiting
    2. Abdominal Pain
    3. Pancreatitis
  5. Ocular
    1. Blurred Vision
    2. Double Vision
    3. Progressive Vision Loss to blindness

V. Lab

  1. Serum Methanol level
    1. Available at many community hospitals
    2. Toxic levels >10 mg/dl
  2. Serum Lipase or Serum Amylase
  3. Metabolic panel
    1. Decreased serum bicarbonate
    2. Anion Gap Metabolic Acidosis (due to formic acid, Lactic Acid)
    3. Osmolal Gap
    4. Hypomagnesemia
    5. Hypophosphatemia
    6. Increased Serum Creatinine (Acute Kidney Injury)

VI. Differential Diagnosis

VII. Complications

  1. Vision Loss
    1. Formic acid causes Optic Nerve demyelination
    2. Occurs with serum Methanol levels >20 mg/dl
    3. Onset of ocular changes within 48 hours of ingestion
  2. Parkinsonism
    1. Methanol and metabolites cause Basal Ganglia damage resulting in Parkinsonian-like signs
    2. Onset weeks after ingestion
  3. Hemorrhagic Pancreatitis
    1. Occurs in more than two thirds of Methanol Poisoning
  4. Death
    1. Minimum toxic dose: 0.1 ml/kg
    2. Minimum lethal ingestion: 1 mg/kg
    3. Even one tbs of 40% Methanol can kill an adult

VIII. Management

  1. Avoid Gastric Decontamination (not helpful, rapid absorption)
  2. Administer folinic acid (or Folic Acid): 1 mg/kg up to 50 mg
  3. Fomepizole (Antizol)
    1. Start immediately if Methanol toxicity is suspected
    2. Continue Fomepizole if
      1. Methanol level >20 mg/dl
      2. Osmolal Gap >10 mOsm/L
      3. Serum bicarbonate <20 mmol/L
  4. Hemodialysis Indications
    1. Severe acidosis with pH <7.25
    2. Methanol Level >50 mg/dl
    3. Visual Symptoms
  5. Disposition
    1. Admit all patients requiring Fomepizole or Hemodialysis
    2. Discharge Indications at 4-6 hours
      1. Normal bicarbonate and Osmolal Gap

IX. References

  1. Korabathina in Ramachandran (2012) Methanol Toxicity, EMedicine
  2. Leikin (1996) Poisoning and Toxicology, Lexi-Comp, Cleveland, p. 957-8
  3. Rodriguez (2022) Crit Dec Emerg Med 36(4): 26-31
  4. Swadron and Nordt in Herbert (2013) EM:Rap 13(8): 3
  5. Tomaszewski (2019) Crit Dec Emerg Med 33(7): 28

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Ontology: Methanol (C0001963)

Definition (NCI) Used as a solvent and as an intermediate in chemical synthesis. Component of deicing mixtures and preservatives. Toxic.
Definition (MSH) A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.
Definition (CSP) colorless, flammable liquid, CH3OH; an alcohol used in chemical synthesis, in antifreeze, and as a solvent; ingestion of methanol is toxic and may cause blindness.
Concepts Organic Chemical (T109) , Hazardous or Poisonous Substance (T131) , Pharmacologic Substance (T121)
MSH D000432
SnomedCT 259221006, 311730004, 29846004
LNC LP14349-2, MTHU005019
English Alcohol, Methyl, Carbinol, Methanol, Alcohol, Wood, Wood naphtha, Wood Alcohol, Methanol [Chemical/Ingredient], wood alcohol, carbinol, methanol, alcohol wood, Methyl Alcohol, methyl alcohol, METHYL ALCOHOL, Wood alcohol (substance), Methyl alcohol (substance), METHANOL, Methyl alcohol, Methanol (substance), Methyl alcohol (substance) [Ambiguous], Wood alcohol, ALCOHOL,METHYL, Alcohol Methyl
Spanish alcohol de madera, alcohol de quemar, alcohol de madera (sustancia), alcohol metílico (sustancia), alcohol metílico (concepto no activo), alcohol metílico, metanol, metanol (sustancia), Metanol, Alcohol Metílico
Swedish Träsprit
Czech methylalkohol, methanol
Finnish Metanoli
French Alcool de bois, Alcool méthylique, Méthanol
Japanese メチルアルコール, カルビノール, 木精, メタノール, アルコール-メチル
Italian Spirito di legno, Carbinolo, Alcol metilico, Metanolo
Croatian METANOL
Polish Metanol, Alkohol metylowy
Portuguese Metil Álcool, Metanol, Álcool Metílico
German Alkohol, Methyl-, Methanol, Methylalkohol

Ontology: Accidental poisoning by methyl alcohol (C0261439)

Concepts Injury or Poisoning (T037)
ICD9 E860.2
SnomedCT 216640006, 216642003, 216643008, 157826001, 216644002
English Accid.pois.- wood alcohol, Accid.pois.-methyl alcohol NOS, Accidental poisoning by methyl alcohol NOS, Accid pois - methyl alcohol, Accidentl poisoning - methanol, accidental poisoning by wood alcohol (diagnosis), accidental poisoning by wood alcohol, accidental poisoning by methyl alcohol (diagnosis), accidental poisoning by methyl alcohol, Acc poisn-methyl alcohol, Accidental poisoning by wood alcohol, Accidental poisoning by wood alcohol (disorder), Accidental poisoning by methyl alcohol (event), Accidental poisoning by methyl alcohol NOS (disorder), Accidental poisoning by methyl alcohol, Accidental poisoning by methanol, Accidental poisoning by methyl alcohol (disorder), Accidental poisoning by methyl alcohol NOS (event), Accidental poisoning by wood alcohol (event)
Spanish intoxicación accidental por alcohol metílico (evento), intoxicación accidental por alcohol metílico, SAI (evento), intoxicación accidental por metanol (evento), intoxicación accidental por alcohol metílico (trastorno), intoxicación accidental por metanol (trastorno), intoxicación accidental por metanol, intoxicación accidental por alcohol de madera, intoxicación accidental por alcohol metílico, intoxicación accidental por alcohol metílico, SAI (trastorno), intoxicación accidental por alcohol metílico, SAI