Liar Liar Pants on Fire – The Medical Science Behind Pathological Liars

While the occasional white lie is considered to be a normal part of social interactions, repeated and elaborate fabrications cross into a very different territory. But what do you do when you realise that either you or the person you love is a pathological liar?

Pathological liars tell compulsive lies without a clear motive. This type of lying is different than non-pathological lying, where the lie is often beneficial in some way. For example, a person may lie to avoid social embarrassment. While some people lie more frequently than others, it is not typically a sign of a mental health condition.

Pathological lying is different. It may be a sign of an underlying mental health condition, such as a personality disorder.

In this article, we discuss pathological lying in more detail, including how to recognize it and how to cope with this behaviour in others.

What is Pathological Lying?

A key feature of a pathological lie is that it has no obvious motivation. It is usually possible to determine why someone has told a lie — such as to benefit themselves or avoid an embarrassing or stressful social situation — but pathological lying occurs for no clear reason and does not seem to benefit the individual. It is unclear whether a person who pathologically lies is aware of their deceit or is capable of thinking rationally about their lies. Pathological lying can make socializing difficult and lead to significant interpersonal problems with loved ones and colleagues.


Since there has been little research in this area, the causes of pathological lying are unknown. In fact, it is unclear whether pathological lying is a symptom of another condition or a condition itself. For instance, compulsive lying is a feature of several other conditions, such as factitious disorder and personality disorders.

Factitious Disorder

Factitious disorder — sometimes called Munchausen’s syndrome — is a condition in which a person acts as though they are physically or mentally ill when they are not. Munchausen’s syndrome by proxy is when someone lies about another person having an illness. This condition is most common in mothers, who feign illness in their child and lie to a doctor about it.

The causes of factitious disorder are unknown, although theories suggest that causes can range from biological or genetic causes to childhood abuse or neglect, substance abuse or a personality disorder. Speaking of which:

Personality Disorders

Pathological lying is a possible symptom of certain personality disorders, including:

  • borderline personality disorder (BPD)
  • narcissistic personality disorder (NPD)
  • antisocial personality disorder (APD)

BPD is a condition that makes it difficult for a person to regulate their emotions. People with BPD may experience severe mood swings, feel greater instability and insecurity, and not have a stable sense of self.

The hallmarks of NPD are fantasies of immense importance and the need for admiration and special treatment.

Researchers argue that while pathological lying may, in theory, occur in people with APD, those with this condition often lie for personal gain or pleasure.

A person with BPD or NPD may lie to distort reality into something that fits with the emotions that they are feeling, rather than the facts. These personality disorders can lead to significant challenges with interpersonal relationships.

Signs and Symptoms

Pathological lies often differ from ordinary lies in that they are easy for others to verify as incorrect.

Pathological lies are compulsive and may start small. The lies can gradually become more elaborate and dramatic, particularly if they are necessary to cover up for an earlier lie. They often become complicated by unnecessary amounts of detail.

People who lie frequently are not necessarily pathological liars. The most distinguishing feature of a pathological lie is that it does not have a motive. Therefore, a person who frequently exaggerates stories to make themselves appear more interesting or consistently lies to cover up mistakes that they have made is unlikely to be pathologically lying. These are clear motives that advance particular interests.

Pathological lies are easy for others to verify, which can ultimately be harmful to the person who tells them. For example, the individual may make false accusations or grandiose claims about their past that are simple for others to check.


Pathological lying is not a formal diagnosis, but a doctor or therapist may recognize the behaviour as a sign of another underlying condition, such as a personality disorder or factitious disorder. These disorders include overlapping symptoms, including compulsive lying. People with these conditions also display other signs. It is possible for pathological lying to be an independent symptom, as some people engage in pathological lying without having any underlying medical condition. It can be challenging for a doctor to determine whether someone is engaging in pathological lying because there are no psychological or biological tests for it.


If a doctor suspects pathological lying is part of an underlying personality disorder, they may suggest psychotherapy. As pathological lying is not a recognized condition, there are no formal treatments for it. If a doctor suspects that an underlying condition is causing the lying, they may suggest treatment for that condition. For example, treatment for personality disorders usually involves psychotherapy or medication. As pathological lying can be harmful to others, a doctor may also suggest therapy for those close to the individual. A therapist will work with them to help them manage their responses to the problem.

So, now that you know a bit more about pathological lying, what are your views on the condition? Share them in the comments section below.

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