We all know that person — the one who leaves you feeling worse off after interacting with them. Maybe it’s a manipulative family member or a co-worker who can’t stop complaining about every little thing. It’s common to refer to these people as being toxic. But it’s important to keep in mind that this term isn’t grounded in psychology and doesn’t have a simple definition. If you have a hard time dealing with someone in your life, it’s helpful to start by pinpointing problematic behaviors, rather than simply labeling them as being toxic.