Someone who believes their own lies is most commonly called a pathological liar. The clinical term for this behavior is pseudologia fantastica, also known as mythomania. What sets this apart from ordinary dishonesty is that the person isn’t just choosing to deceive others. Over time, their fabrications blend with real memories until the line between truth and fiction becomes genuinely blurred, even to them.
Pathological Lying vs. Ordinary Lying
Everyone lies occasionally, whether to spare someone’s feelings or avoid an awkward situation. Ordinary lies are strategic: you know the truth, and you deliberately say something different. A pathological liar operates on a fundamentally different level. Their lying is excessive, chronic, and often begins in early adolescence and persists into adulthood. The stories they tell tend to be a mixture of fact and fiction, woven together so tightly that even the liar may struggle to separate what actually happened from what they invented.
The content of these fabrications is also distinct. Pathological lies frequently involve self-aggrandizing personal roles, placing the liar at the center of dramatic or impressive events. To the person telling the story, these narratives feel plausible. To everyone else, they often seem implausible or outright impossible. When confronted with clear evidence, pathological liars can sometimes acknowledge the truth, which is one way clinicians distinguish this from a fixed delusion, where a person cannot be talked out of a false belief no matter what evidence is presented.
Why Someone Starts Believing Their Own Lies
Pathological lying appears to be driven by unconscious motives rather than the external, calculated goals behind a normal lie. A regular liar wants something specific: to avoid punishment, gain an advantage, or protect a secret. A pathological liar may not have a clear external payoff at all. The lying itself seems to serve a psychological need, often tied to self-image or emotional regulation.
There’s also an element of impulse and lost control. Research has noted that pathological lying often appears impulsive, with what clinicians describe as “dyscontrol,” meaning the person may not fully choose to lie in a given moment. Over years or decades of habitual fabrication, the rehearsed stories become so familiar that they start to feel like real memories. Pathological liars may genuinely believe their falsehoods, or they may have repeated them so many times that they can maintain confident eye contact and display none of the usual signals of deception. Either way, the result looks the same from the outside: a person who seems utterly convinced by stories that never happened.
Related Terms You Might Encounter
Several related words describe overlapping but slightly different behaviors:
- Mythomaniac: Another name for someone with pseudologia fantastica. “Mythomania” is the older term, used more commonly in European psychiatry.
- Compulsive liar: Someone who lies out of habit or impulse, often without a clear reason. Compulsive lying overlaps heavily with pathological lying, and the two terms are sometimes used interchangeably, though compulsive lying places more emphasis on the inability to stop rather than on believing the lies.
- Confabulator: Someone who fills in memory gaps with invented details without realizing it. Confabulation is typically linked to brain injuries or neurological conditions like dementia, not personality patterns. The person isn’t “lying” in any intentional sense; their brain is producing false memories to patch holes.
- Narcissist: People with narcissistic personality disorder frequently distort the truth to protect their self-image, and they may internalize those distortions over time. Not all pathological liars are narcissists, but the overlap is significant.
Personality Disorders That Involve Self-Deception
Pathological lying commonly shows up alongside specific personality disorders. Antisocial personality disorder and narcissistic personality disorder are the two most frequently linked. In antisocial personality disorder, lying serves as a tool for manipulation and control. In narcissistic personality disorder, the lies tend to revolve around maintaining a grandiose self-image, and the person may genuinely lose track of where reality ends and the inflated version of themselves begins.
Borderline personality disorder is another condition where chronic dishonesty can take root, though the motivation is different. Here, deception often becomes a way to ward off perceived rejection or abandonment. The lies are less about self-glorification and more about keeping relationships intact at any cost. Compulsive lying can also appear alongside bipolar disorder, ADHD, impulse control issues, and substance dependency.
It’s Not an Official Diagnosis
Despite being recognized and studied for over a century, pathological lying has never been included as a standalone diagnosis in the DSM-5 or the ICD-11, the two major systems clinicians use to classify mental health conditions. The only place lying appears in the DSM at all is as a non-essential feature of factitious disorder, where a person fabricates illness to assume a sick role. Some researchers have argued that pathological lying could be classified as part of the impulse control disorder spectrum, but no consensus has been reached.
This gap has real consequences. Without a formal diagnosis, there are no standardized diagnostic criteria, which means clinicians rely on their own judgment to identify the behavior. It also means there’s been limited research into what treatments actually work.
How Pathological Lying Is Treated
Because pathological lying lacks a formal diagnosis, there are no research-backed, officially recommended treatments. Clinicians working with pathological liars generally rely on approaches that have proven effective for related conditions. Cognitive behavioral therapy is widely considered the most promising option. The core idea is helping the person become aware of when and why they lie, then gradually reinforcing honest behavior while reducing the automatic impulse to fabricate.
Behavioral techniques like habit reversal training take a practical approach: the person learns to recognize the moments just before a lie happens and practice alternative responses. Group therapy has also shown promise for a specific reason. In a group setting, other members can call out dishonesty in real time, which removes the burden from the therapist and creates social accountability that’s harder to dismiss. The challenge remains that without formal research trials, clinicians are largely working from clinical experience and educated guesses about what helps most.
How to Recognize the Pattern
If you’re trying to figure out whether someone in your life fits this description, look for a few key patterns. Their stories tend to be elaborate and detailed, often placing them in a heroic, victimized, or otherwise central role. The lies aren’t one-off incidents but a chronic pattern stretching back years. When caught, they may adjust the story rather than fully admit to lying, or they may seem genuinely confused about what actually happened versus what they fabricated.
The most telling sign is the absence of a clear motive. If someone lies to get out of trouble or gain something tangible, that’s ordinary deception. When someone lies in situations where the truth would have been perfectly fine, or when the lie actually makes their situation worse, you’re likely looking at something deeper. The lying has become its own reward, serving psychological needs the person may not even be aware of.