According to the Stanford Encyclopedia of Philosophy (2009), friendships are intimate relationships with a mutual concern for the welfare and wellbeing of the other. Some things that friends may do for each other: spend time, perform duties, give advice, etc. Most importantly, friends genuinely want the best for each other.
Friendships that lose this most important relationship feature may become toxic. Toxic friendships lack sincerity, compassion, concern, and support. They do us more harm than good. Toxic friends are overly critical (of themselves and others), perpetually negative, very competitive, jealous and spiteful, self-involved, abusive, and often unapologetic.
Are emotionally drained after contact with your friend?
Is your friend consistently negative in their interactions with you?
Do you make bad decisions when with them? Or by their influence?
Are your friends and family opposed to spending time with this person?
Do you feel that you give more than you get in this relationship?
Are your needs often unmet in the friendship with this person?
If you can answer yes to 2 or more of these questions, it may be time to clean up some hazardous material!