BPD vs Bipolar Disorder and How to Tell the Difference
The clearest difference between BPD and bipolar disorder is how moods change. Bipolar disorder, once called manic depression, causes distinct mood episodes that last days to weeks. Borderline personality disorder (BPD) involves ongoing emotional instability, with mood shifts that usually last hours and are often set off by relationship stress. The two can also occur together.
The risk of self-harm and suicide is higher in both bipolar disorder and BPD than in the general population. If you or someone you love is struggling right now, call or text 988 to reach the Suicide and Crisis Lifeline, free and available 24/7. In an emergency, call 911.
Why Are BPD and Bipolar Disorder So Often Confused?
If you have been told you might have one of these conditions, or you have wondered which one fits a person you love, the confusion makes sense. Both can involve intense moods, impulsive decisions, depression, irritability, and strained relationships. Clinicians confuse them too. Borderline personality disorder is listed among the most common conditions that have to be ruled out when someone is evaluated for bipolar disorder, and misdiagnosis runs in both directions.
Part of the problem is language. People say “I’m so bipolar today” to describe a bad afternoon, and “manic depression,” the older name for bipolar disorder, still shows up in search results and conversation. Neither phrase maps neatly onto a diagnosis. The real distinctions show up in timing, triggers, and how a person experiences themselves over months and years.
What Is Bipolar Disorder (Manic Depression)?
Bipolar disorder, formerly called manic-depressive illness or manic depression, is a mood disorder defined by episodes. Under DSM-5-TR criteria, a manic episode lasts at least 7 consecutive days, or any length of time if the person needs to be hospitalized. A hypomanic episode is a milder elevated state that lasts at least 4 consecutive days. Depressive episodes typically last at least two weeks.
The two main types differ by the kind of high a person experiences:
- Bipolar I disorder requires at least one full manic episode. Depressive episodes are common but not required for the diagnosis.
- Bipolar II disorder involves at least one hypomanic episode and at least one major depressive episode, with no history of full mania.
During mania or hypomania, a person may feel unusually energized or irritable, talk quickly, take on many projects at once, and need far less sleep without feeling tired. Symptoms most often begin in late adolescence or early adulthood. Because the condition is long-term, most people benefit from ongoing care, which you can read more about in our guide to how long bipolar disorder lasts and on our bipolar disorder treatment page.
What Is Borderline Personality Disorder?
BPD is a personality disorder, which means it describes a long-standing pattern in how a person feels, thinks about themselves, and relates to others, rather than a set of separate episodes. A DSM-5-TR diagnosis requires at least 5 of 9 criteria, beginning by early adulthood and showing up across many areas of life. Those criteria include:
- Intense efforts to avoid real or imagined abandonment
- Unstable, intense relationships that swing between idealizing and devaluing others
- An unstable self-image or sense of identity
- Impulsivity in at least two areas that can cause harm, such as spending or substance use
- Recurrent suicidal behavior or self-harm
- Emotional reactivity, with intense moods that usually last a few hours and rarely more than a few days
- Chronic feelings of emptiness, intense anger that is hard to control, and stress-related paranoia or dissociation
BPD carries more stigma than almost any other diagnosis, and much of it is outdated. People living with BPD often feel emotions more intensely and take longer to return to baseline. That is a real source of pain, and it responds to treatment. Our borderline personality disorder treatment page explains how therapy targets these patterns directly.
BPD vs Bipolar: Key Differences at a Glance
| Feature | Bipolar Disorder | Borderline Personality Disorder |
|---|---|---|
| Type of condition | Mood disorder | Personality disorder |
| How long mood shifts last | Mania at least 7 days; hypomania at least 4 days; depression usually 2 weeks or more | Usually a few hours, rarely more than a few days |
| Pattern over time | Distinct episodes, often with steadier periods in between | Ongoing, day-to-day emotional reactivity |
| Common triggers | Episodes can arise without an obvious trigger; sleep loss and stress can play a role | Often interpersonal: conflict, perceived rejection, fear of being left |
| Sense of self | Self-esteem may inflate during mania, then return to the person’s baseline | Persistent identity disturbance and chronic emptiness |
| Sleep | Decreased need for sleep during mania or hypomania is a core symptom | Sleep may be disrupted by distress, but reduced need for sleep is not a defining feature |
| Family history | Strongly heritable; often runs in families | Also has a genetic component; a close relative with BPD raises risk |
| Typical onset | Late adolescence or early adulthood | Usually diagnosed in late adolescence or early adulthood |
| Primary treatment | Medication (mood stabilizers or certain antipsychotics) plus psychotherapy | Structured psychotherapy such as DBT, MBT, or schema therapy |
| Role of medication | Central, usually long-term | Adjunctive and time-limited, aimed at specific symptoms |
Duration and pattern of mood changes
Timing is the single most useful clue. A person with bipolar disorder might have a week or more of elevated energy and little sleep, followed later by weeks of depression, with long stretches in between. A person with BPD might move from calm to despair to anger within one day, then settle by evening.
Bipolar disorder
Mood over several weeks
Sustained episodes lasting days to weeks, then a return toward baseline.
Borderline personality disorder
Mood over a single day
Rapid shifts, often in response to what is happening between people.
Triggers and sense of self
BPD mood shifts tend to follow events: a text that goes unanswered, a partner who seems distant, criticism at work. Bipolar episodes can start with no clear cause. Identity is another marker. With BPD, the sense of who you are can feel shaky or empty much of the time. With bipolar disorder, self-image usually changes with the episode and returns afterward.
Sleep, family history, and onset
Needing only a few hours of sleep for days while feeling energized is a hallmark of mania and hypomania. Family history points toward bipolar disorder more strongly, since NIMH notes its risk is mostly explained by heredity, though BPD also has a genetic component. Both conditions usually emerge in the late teens or early twenties, so age of onset rarely settles the question on its own.
Can You Have Both BPD and Bipolar Disorder?
Yes. A 2016 meta-analysis in the Journal of Affective Disorders found that about 21.6% of people with bipolar disorder also had BPD, and about 18.5% of people with BPD also had bipolar disorder. When both are present, treatment usually needs to address each one: medication to stabilize mood episodes and psychotherapy to build emotional regulation and relationship skills.
Substance use is common alongside both conditions, too. When alcohol or drugs are part of the picture, integrated dual diagnosis treatment treats the mental health condition and the substance use together, which avoids the back-and-forth of separate programs.
How Is Treatment Different for Bipolar Disorder and BPD?
This is where an accurate diagnosis pays off, because the first-line approaches are not the same.
Treating bipolar disorder
Medication is the foundation. Mood stabilizers such as lithium or valproate, or certain antipsychotic medications, help prevent episodes or reduce their severity. Psychotherapy adds a second layer: interpersonal and social rhythm therapy (which focuses on steady sleep and daily routines) and cognitive behavioral therapy both have research support. Some people with bipolar disorder also benefit from emotion regulation skills, a question we cover in does DBT therapy for bipolar work. Learn more on our bipolar disorder treatment program page.
Treating borderline personality disorder
Psychotherapy is the primary treatment. Dialectical behavior therapy (DBT) was developed specifically for BPD and teaches concrete skills for emotion regulation, distress tolerance, mindfulness, and relationships. Mentalization-based treatment (MBT) and schema therapy also have evidence behind them. The American Psychiatric Association’s 2024 practice guideline recommends a structured psychotherapy that targets the core features of BPD, and suggests that any medication be time-limited, aimed at a specific symptom, and used alongside therapy. There are no FDA-approved medications for BPD itself, though medication can help treat co-occurring conditions such as depression.
The McLean Study of Adult Development followed 290 people with BPD for 16 years. By the end, 99% had reached a symptom remission lasting at least two years, and 78% had one lasting at least eight years. Recovery, defined as remission plus good social and work functioning, took longer: 60% reached a recovery lasting two years. Symptoms can return, and support still matters, but BPD is far from a life sentence.
Why a Professional Diagnosis Matters
Online quizzes and social media checklists can start a useful conversation, but they cannot tell these two conditions apart. A licensed clinician looks at the full history: how long mood changes last, what came before them, sleep patterns, family history, substance use, and how relationships and identity have felt over years. Sometimes that takes more than one visit, or mood tracking over several weeks.
Getting it right changes the plan. Someone with BPD who is treated only with bipolar medication may miss the therapy that helps most. Someone with bipolar disorder whose manic episodes go unrecognized may go without the mood stabilization they need. If you are unsure, bring your questions to a professional rather than settling on a label yourself.
Mental Health Treatment at Rockland Recovery Group
Rockland Recovery Group treats mental health conditions as a primary focus, including bipolar disorder and BPD, at our behavioral health centers in Sharon and Bedford, Massachusetts. Care is offered at two structured levels. A partial hospitalization program provides about 20 or more hours of treatment per week while you live at home, and an intensive outpatient program provides 9 to 15 hours per week. Not sure which fits? Our PHP vs IOP guide walks through it, and our article on day treatment programs for bipolar disorder explains what a typical day looks like.
Programming includes psychiatric care, individual therapy, and group work, with DBT skills training as part of our approach to BPD. You can see the full range of conditions we treat on our mental health treatment page, or read about our BPD treatment program in detail.
Sources
Clinical information in this article comes from the sources below and is reviewed under our editorial standards.
- National Institute of Mental Health. Bipolar Disorder. www.nimh.nih.gov
- National Institute of Mental Health. Borderline Personality Disorder. www.nimh.nih.gov
- StatPearls. Bipolar Disorder. National Library of Medicine. www.ncbi.nlm.nih.gov
- StatPearls. Borderline Personality Disorder. National Library of Medicine. www.ncbi.nlm.nih.gov
- American Psychiatric Association. Updated Borderline Personality Disorder Guideline (news release), 2024. www.psychiatry.org
- National Institute for Health and Care Excellence. Borderline personality disorder: recognition and management (CG78). www.nice.org.uk
- Zanarini MC, Frankenburg FR, Reich DB, Fitzmaurice G. Attainment and stability of sustained symptomatic remission and recovery among patients with borderline personality disorder and axis II comparison subjects: a 16-year prospective follow-up study. American Journal of Psychiatry, 2012. psychiatryonline.org
- Fornaro M, Orsolini L, Marini S, et al. The prevalence and predictors of bipolar and borderline personality disorders comorbidity: systematic review and meta-analysis. Journal of Affective Disorders, 2016. www.sciencedirect.com
This article is for information and does not replace advice from a licensed clinician. If someone is unresponsive, breathing slowly, or has blue lips after using opioids, give naloxone if you have it and call 911. The Massachusetts Good Samaritan law protects people who call for help during an overdose. For a mental health crisis, call or text 988.
