Individuals with narcissistic personality disorder, according to the DSM-5, exhibit five or more of the following, which are present by early adulthood and across contexts:

A grandiose sense of self-importance

Preoccupation with fantasies of unlimited success, power, brilliance, beauty, or ideal love

Belief that one is special and can only be understood by or associate with special people or institutions

A need for excessive admiration

A sense of entitlement (to special treatment)

Exploitation of others

A lack of empathy

Envy of others or the belief that one is the object of envy

Arrogant, haughty behavior or attitudes

Individuals with NPD can be easily stung by criticism or defeat and may react with disdain or anger—but social withdrawal or the false appearance of humility may also follow according to the DSM-5.

A sense of entitlement, disregard for other people, and other aspects of NPD can damage relationships. While a person with NPD may be a high-achiever, the personality disorder can also have a negative impact on performance (due to, for instance, one's sensitivity to criticism).

Researchers have reported associations between NPD and high rates of substance abuse, mood, and anxiety disorders. These may be attributable to characteristics such as impulsivity and the increased experience of shame in people with NPD.

The presence of narcissistic traits in adolescence does not necessarily imply that a person will have NPD as an adult.