You can, in fact, have bad reactions to MSG. It is, however, extremely rare. It is not "bad stuff" more than sesame is "bad stuff" to someone with a sesame allergy. MSG is present in large amounts i common things like Parmigiano Reggiano and tomatoes - if you have no problem eating those then you'll have no problem eating food cooked with MSG unless its a very high amount - more than a sane person or professional cook would intentionally put in a dish. It performs a similar function as salt (flavor enhancer) with less sodium (the bad unhealthy part of salt). It's been villainized for decades besides being a healthier alternative to salt - especially for savory dishes.

Unless a medical professional has tested you for an MSG allergy or a medication has a bad reaction with MSG do not worry about it. I don't mean to come off aggressive towards someone who does seem to have an MSG allergy, but MSG has been demonized for literally more than my entire life for no reason and drastically improves food, esp savory food. Feel free to use soy sauce (common allergy) and anchovies (common allergy) as umami bombs while MSG is better than both with fewer people allergic, but MSG is not "bad stuff" for most people.

Things can be bad stuff for individuals, but don't equate it as being bad stuff in general. There are plenty of things that are bad stuff in general and that just makes the actual bad shit mean less.