See also under XIVa. Known since the 1940s (PMID 18883450). Comprehensive list of causal drugs and chemicals available at PMID 1564446. Methemoglobin is the oxidized (Fe3+) species of hemoglobin (Fe2+). Patients present with slate-grey cyanosis, low SpO2, normal SaO2 and PaO2. Normally, methemoglobin is <1%. Levels above 40% can be life-threatening, producing pulmonary edema, cardiovascular collapse (PMID 17122537) CNS disturbances and death. Management includes i.v. methylene blue. A possible rebound increase in MeHb upon treatment requires close monitoring. Excess methylene blue can also produce methemoglobinemia

Last update : 01/01/1970

Causative drugs


Hydrocarbons (petrochemicals: petroleum, petrolatum, paraffin, vaseline, naphta, jet fuel (kerosene), Diesel, gasoil), ointments, salad oil, variegated oils, butter). Aspirated

I.b I - Interstitial/parenchymal lung disease
I.b - Pneumonitis (ILD)
I.g I - Interstitial/parenchymal lung disease
I.g - Pulmonary fibrosis
I.j I - Interstitial/parenchymal lung disease
I.j - Exogenous lipoid pneumonia (subacute, acute)
I.z I - Interstitial/parenchymal lung disease
I.z - An area or areas of consolidation
I.ae I - Interstitial/parenchymal lung disease
I.ae - Hydrocarbon pneumonitis
I.af I - Interstitial/parenchymal lung disease
I.af - Chemical (toxic) pneumonitis
I.ag I - Interstitial/parenchymal lung disease
I.ag - Fire-eater's lung/pneumonitis
II.b II - Pulmonary edema - Acute lung injury - ARDS
II.b - ARDS - Acute lung injury
III.a III - Pulmonary/alveolar./airway hemorrhage/bleeding
III.a - Alveolar hemorrhage (AH), diffuse AH (DAH)
III.c III - Pulmonary/alveolar./airway hemorrhage/bleeding
III.c - Hemoptysis
IV.k IV - Airway involvement
IV.k - Bronchiectasis
V.a V - Pleural and/or pericardial involvement
V.a - Pleural effusion (uni- or bilateral)
VIII.d VIII - Central-large-upper airway (incl. pharyngeal-nasal) involvement
VIII.d - Thermal (burns, frostbite), chemical or caustic facial and/or airway injury
XI.b XI - Miscellaneous
XI.b - Chest pain (acute or subacute), lone or prominent
XI.s XI - Miscellaneous
XI.s - Sniffing death - Death from inhalation of compound
XIV.a XIV - Hemoglobinopathies - Abnormal hemoglobin states (acquired)
XIV.a - Methemoglobinemia
XV.as XV - Pathology
XV.as - Path: Fire eater's lung
XVI.b XVI - Imaging
XVI.b - Imaging: Ground-glass opacities (GGO) / shadowing
XVI.f XVI - Imaging
XVI.f - Imaging: Bibasilar opacities/shadowing
XVI.k XVI - Imaging
XVI.k - Imaging: An area or areas of consolidation
XVI.ab XVI - Imaging
XVI.ab - Imaging: Cavitating/cavitary lung nodule, mass or nodules (see also Iq, XIs, XIIi, XVIaa and XVIIp)
XVI.ah XVI - Imaging
XVI.ah - Imaging: Pneumatoceles (see also XVIaf)
XIX.a XIX - Cytological, biochemical features of/in BAL, pleural fluid or FNA
XIX.a - BAL: An excess proportion of lymphocytes
XIX.h XIX - Cytological, biochemical features of/in BAL, pleural fluid or FNA
XIX.h - BAL: Exogenous (oil red O-stainable) lipids in BAL macrophages