PEG, found in Miralax and made from ethylene glycol (main ingredient in antifreeze), is known to cause allergic and anaphylactic reactions

https://aacijournal.biomedcentral.com/articles/10.1186/s13223-019-0327-4

https://aacijournal.biomedcentral.com/articles/10.1186/s13223-016-0172-7

https://www.aaaai.org/global/latest-research-summaries/New-Research-from-JACI-In-Practice/inactive