Research has linked friendship and social support to better physical health outcomes, including lower rates of heart disease. One study revealed that young men and women who discussed difficult parts of their lives had a lower pulse and blood pressure when a supportive friend accompanied them. Friendship is an important factor in our physical well-being, but what effects does it have on our mental health?

A 2009 study surveyed 300 men and women at a free health clinic in Buffalo, New York. They found that respondents with insufficient perceived social support were the most likely to suffer from mental health disorders such as anxiety and depression. A good friendship requires a balance between individuals–one where the needs of each are met. Positive friendships have a myriad of benefits such as increased feelings of belonging, purpose, and confidence, amplified levels of happiness, reduced levels of stress, and improved self-worth.

While good friends can support you through traumatic events and are able to help you to quit bad habits, toxic friendships can leave you feeling drained, stifled, anxious and often unequal. Friendships are unique because they are tied to so many aspects of your life–your family, work, hobbies. When you have a toxic friendship, these feelings can permeate all of these areas as well. If a particular friendship is isn’t meeting your needs, it may be time to reassess whether it deserves a space in your life.

Humans are social animals by nature. Our friendships can have a tremendous impact on our lives–which is why it’s important to make sure that your friends leave you feeling supported, understood, and happy.

Editor’s Note: This post was originally published in January 2015 and has been edited and updated for accuracy and comprehensiveness.