Borderline Personality Disorder vs Bipolar: Signs, Symptoms, and Treatment

Life often feels like an unpredictable ride, and sometimes the way we experience the world, our emotions, and our relationships feels overwhelming, confusing, and maybe even "too much." Maybe you’ve heard terms like borderline personality disorder vs bipolar tossed around, often incorrectly, and you wonder if they could explain what you or a loved one is going through. 

Despite being distinct diagnoses, BPD and bipolar disorder are frequently misunderstood and conflated, largely due to the shared core symptom of intense affective instability (rapid mood swings). However, the mood shifts in BPD are typically reactive to interpersonal triggers and short-lived (hours), whereas Bipolar episodes are often endogenous and last for days or weeks. This diagnostic confusion often leads to incorrect treatment, underscoring the necessity of a thorough clinical assessment to determine the appropriate care.

This path to healing requires not just professional insight, but a deeply personal journey. For example, take the experience of Dominique, who navigated this complex path firsthand. As an ambitious career woman in her 20s, therapy client Dominique never thought a mental health condition like this could possibly affect her. 

“Six years into therapy, I was diagnosed with bipolar II. It was an Earth-shattering identity crisis. I never expected someone like myself—who I thought of as very high-functioning—to have such a serious mental health condition.” She goes on to share, “With time, I was able to accept that the diagnosis actually allowed me to build more self-awareness and self-compassion as opposed to if I didn’t have that understanding of myself.” 

Bipolar disorder vs borderline personality disorder

Bipolar disorder is classified as a mood disorder, whereas borderline personality disorder (BPD) is a personality disorder. Simply put, bipolar disorder is about intense cyclical shifts in the brain that lead to extreme highs and lows. Borderline personality disorder, however, is a long-term pattern of intense emotions and unstable relationships, which is influenced by both a person's brain and what they've been through.

This fundamental distinction dictates everything from symptom patterns to the most effective treatments.

• Bipolar disorder is characterized by distinct, prolonged episodes of elevated or irritable mood (mania or hypomania) that cycle with periods of significant depression. These episodes typically last for days, weeks, or even months at a time, according to the National Institute of Mental Health (NIMH).
• Borderline personality disorder involves a pervasive pattern of instability in moods, relationships, self-image, and behavior. These mood changes are often rapid, lasting hours or a few days, and are usually triggered by events, especially those related to relationships or fear of abandonment.

Think of it this way: for someone with bipolar disorder, the mood shifts are like a large cruise ship changing course. It takes a long time and is an entirely new journey. For someone with BPD, the mood shifts are like a small speedboat. It can turn on a dime, often in reaction to what's happening around it.

What are some borderline personality disorder symptoms?

BPD is defined by instability across several areas of a person's life. According to NIMH, about 1.4% of U.S. adults have BPD, though this may be higher as many people are misdiagnosed.

Signs of borderline personality disorder

• Frantic efforts to avoid real or imagined abandonment: This can involve clinging behavior or pushing people away before they can leave.
• A pattern of intense and unstable relationships: These relationships often cycle between extremes of idealization ("you’re the best!") and devaluation ("you're awful!").
• Markedly and persistently unstable self-image or sense of self: Goals, values, and career paths may change often, and there's a chronic sense of who they are.
• Impulsivity in at least two areas that are potentially self-damaging: Examples include reckless driving, excessive spending, substance misuse, or binge-eating.
• Recurrent suicidal behavior, gestures, or threats, or self-mutilating behavior: Self-harm is often used as a way to cope with intense emotional pain. Up to 75% of people with BPD have self-harmed at some point. One study found that the lifetime prevalence of suicide attempt was 60% of the BPD subcohort. Remarkably, the lifetime prevalence of suicide attempts in patients with comorbid BD and BPD exceeded 90%.
• Emotional instability: Intense mood swings, with moods changing rapidly from sadness to anger to anxiety, often lasting only a few hours.
• Chronic feelings of emptiness: A persistent feeling that something is missing or that a person is fundamentally "hollow."
• Inappropriate, intense anger or difficulty controlling anger: Frequent displays of temper or physical fights.
• Stress-related paranoid thinking or severe dissociative symptoms: Feeling detached from oneself or reality.

According to licensed professional counselor, Hailey Shafir, “Most of the time, BPD arises from complex trauma and attachment wounds in childhood, and the symptoms of BPD are just defense mechanisms that protect these old wounds. For example, a person with BPD frantically avoids abandonment by shapeshifting to become who others want them to be, instead of who they truly are.” The key to BPD symptoms is that they are a persistent, underlying pattern, a part of the person's personality structure that makes life an emotional rollercoaster.

What are some bipolar disorder symptoms?

Bipolar disorder involves changes in the brain’s natural rhythm of mood and energy, while BPD centers on how a person responds to emotions and relationships, influenced by both their wiring and what they’ve lived through.

The most common types are bipolar I and bipolar II. Cyclothymia, a related but milder disorder, is also part of the bipolar spectrum. The lifetime prevalence of bipolar disorder in the U.S. is estimated to be around 2.4%. 

Signs of bipolar disorder

Bipolar disorder is defined by the presence of mood episodes—depression and hypomania or mania. 

Manic or hypomanic episode (elevated or irritable mood)

• Impulsivity: This can include reckless spending, foolish business investments, or promiscuity.
• Increased activity or energy: Feeling restless or wired.
• Inflated self-esteem or grandiosity: Thinking one is capable of extraordinary things.
• Decreased need for sleep: Feeling rested after only a few hours, or not sleeping at all.
• Rapid speech: Being more talkative than usual or feeling pressure to keep talking.
• Racing thoughts: Feeling like thoughts are moving too fast.
• Distracted: Difficulty staying focused on a task.

A full manic episode can last at least seven days or is so severe that the person needs immediate hospitalization. Hypomania is a less severe form of mania that can last at least four days.

Depressive episode (low mood)

• Persistent sadness, anxiousness, or empty mood
• The inability to experience joy or pleasure (anhedonia)
• Fatigue or low energy
• Difficulty concentrating, remembering, or making decisions
• Changes in appetite or weight
• Sleep issues like insomnia or oversleeping
• Feelings of worthlessness or excessive guilt
• Thoughts of death or suicide

For a depressive episode, symptoms typically last for at least two weeks. Plus, unlike BPD, bipolar disorder has a strong genetic component that can make individuals predisposed to this condition.

Mood duration and triggers

For those trying to sort out BPD vs bipolar, the duration and trigger of the mood change are the most telling factors.

The speed of the shift

• Bipolar disorder: Mood episodes are sustained, lasting days to weeks or even months. They represent a significant change from a person's normal baseline and can occur spontaneously, without an obvious external trigger.
• Borderline personality disorder: Mood swings are rapid, short-lived, and often happen multiple times within a single day, lasting only a few hours.

The role of relationships

For someone with BPD, mood instability is frequently a reaction to real or perceived rejection or conflict in a relationship. A minor argument can send them into a spiral of intense sadness or anger. As therapist Dr. Edward Kilbane explains, "With BPD, mood symptoms change drastically within the same day or from hour to hour... With bipolar disorder, mood symptoms of depression or mania take longer to develop. They're more sustained and less reactive to social stressors."

A celebrity who has openly discussed the complexities of mental health is singer and songwriter Halsey. In a 2019 interview with Rolling Stone, Halsey, who is diagnosed with bipolar disorder, explained how their creative process interacts with their condition, suggesting the long-term, episodic nature of their mood changes: "I know I’m just going to get f**king depressed and be boring again soon... Every time I wake up and realize I’m back in a depressive episode, I’m bummed. I’m like, 'F**k. F**k! This is where we’re going now? OK.'" 

Treatment paths for bipolar vs BPD

Because these two conditions have different underlying mechanisms—one being a mood disorder and the other a personality disorder—the treatments are different, though they can overlap.

Treatment for bipolar disorder

The primary treatment for bipolar disorder involves medication, which can be a mood stabilizer or anti-psychotic to prevent or manage the manic and depressive episodes. Psychotherapy, such as cognitive behavioral therapy (CBT), is also vital to help manage the effects of the disorder on daily life and relationships.

Treatment for borderline personality disorder

The most effective treatment for BPD is psychotherapy, specifically dialectical behavior yherapy (DBT). DBT teaches skills to help a person regulate their emotions, handle distress, improve relationships, and stay present in the moment. While medications aren't a direct treatment for the personality disorder itself, they can be used to manage co-occurring symptoms like anxiety or severe mood swings.

Getting an accurate diagnosis is essential because the wrong treatment can make things worse. An individual with BPD, for instance, may struggle if they are only treated with medications geared toward bipolar disorder because those medications won't address the core issues of emotional regulation and relationship patterns that DBT targets.

The overlap and comorbidity of these two mental health conditions

Research confirms a significant comorbidity between bipolar disorder and BPD, particularly with bipolar II. A large meta-analysis found that 21.6% of individuals with BD also met criteria for BPD, and conversely, 18.5% of individuals with BPD were found to have a comorbid BD diagnosis. This overlap suggests that roughly one-fifth, or 20% of patients in each group, have both conditions. When they occur together, symptoms may be more severe, and managing the conditions can be more complex.

Remember Dominique? Her mental health journey didn’t stop with the bipolar II diagnosis. She explains, “Shortly after, I was also diagnosed with borderline personality disorder. Now, not only did I have a mood disorder, but I had a personality disorder (which somehow felt even more like a character flaw). And to be honest, it got worse before it got better. At one point, it got so bad, I almost voluntarily committed myself to an inpatient program. But through a combination of different therapies—including DBT, IFS, ketamine-assisted psychotherapy, CBT, medication management, and group support through DBSA (Depression and Bipolar Support Alliance), I was able to build enough tools, skills, and community that my diagnoses were no longer the things that were defining my life.” 

It’s important to remember that a mental health diagnosis is simply a roadmap. It’s a tool that points you toward the most effective way to manage your unique set of challenges. It is not a permanent label or a sentence of struggle. 

Whether you're navigating the sustained peaks and troughs of bipolar disorder or the rapid, intense emotional swings of borderline personality disorder, know this: you are not alone. There are entire communities, therapies, and wellness strategies designed to help you find stability, build healthy relationships, and live a meaningful life. The search for a balanced and fulfilling life is a human experience, and your curiosity about these differences is a powerful step toward a brighter future.