PMID 31990264, 32758560, 34130236. Reached epidemic proportions mid-2019, then declining durably. THC, and vitamin-E acetate at the forefront of possible culprit agents. Substances of toxicological interest include ethylene glycol, glycerine, flavoring agents including diacetyl, cannabis (PMID 26347431), tetrahydrocannabinol THC (PMID 25383564, 31491070), vitamin E acetate, ‘sexual enhancers’ such as tadalafil, poppers (NO), or other drugs of abuse (PMID 30245461, 30835796). There is also the risk of nicotine poisoning if contents of a cartridge is taken orally and swallowed, notably by/in children. Careful differential diagnosis and history taking of exposure to tobacco smoke, inhalants, inhaled stimulants, inhaled drugs and/or substances of abuse is indicated in every patient. E-cigarette in patients on oxygen therapy may produce severe facial burns.