The phrase "system overreaction" means when a system or a group of people responds in an excessive or exaggerated manner to a certain situation or stimulus. This reaction is typically much stronger than what is necessary or expected. Full definition
It's clear that your gut microbiome plays a big role in how your immune system handles true threats like harmful bacteria or viruses — but we now know that a lack of enough beneficial bacteria in the gut can contribute to the immune system's inability to distinguish friend from foe, leading to the dreaded immune system overreactions known as allergies. (mindbodygreen.com)
An immune system overreaction causes food allergies. (mayoclinic.org)
This immune system overreaction puts stress on your body. (thehormonediva.com)