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What is the difference between bipolar 1 and bipolar 2?

Bipolar I and bipolar II have separate criteria for diagnosis. Compare bipolar 1 vs. 2, how it is treated, and how to support a loved one with bipolar disorder.
Karen Berger medical writer and reviewer headshot
By | Jun. 1, 2023
Woman talking to healthcare professional: Difference between bipolar 1 and 2

Key takeaways

  • Bipolar I disorder is characterized by manic episodes that last at least seven days or are so severe they require hospitalization and may include depressive episodes. In contrast, Bipolar II disorder involves depressive episodes and hypomanic episodes without the severe mania of Bipolar I.

  • The cause of bipolar disorder is linked to a combination of genetic factors (with up to 90% of patients having a family history of bipolar disorder or depression), brain chemical imbalances, and environmental triggers like stress or lack of sleep.

  • Treatment for both Bipolar I and II disorders typically involves a combination of medication (such as mood stabilizers and, for Bipolar I, possibly additional medication for psychosis) and psychotherapy, with the approach tailored to each individual’s symptoms and experiences.

  • Supporting a loved one with bipolar disorder involves offering understanding, encouragement, and practical help, such as seeking support groups or therapy for family members, to foster a supportive environment conducive to managing the condition.

In this article:

Bipolar disorder affects about 5.7 million adults in the U.S. (about 2.6% of the population), ages 18 years and older every year. 

Bipolar disorder is a chronic mental health condition that dramatically affects mood, energy, and behavior. People with bipolar disorder have intense mood episodes characterized as manic/hypomanic (abnormally happy, impulsive, or irritable) or depressive (sad). People with bipolar disorder often experience neutral moods as well. 

Although there are four types of bipolar disorder, the most common types are bipolar I disorder and bipolar II disorder. 

People with bipolar I disorder experience manic episodes that can be dangerous and require hospitalization. They may or may not have depressive episodes. 

People with bipolar II disorder experience hypomania, a milder form of less disruptive mania. They also experience depressive episodes. 

Continue reading to learn more about the different types of bipolar disorder.

Types of bipolar disorder

There are four types of bipolar disorder, the most common being bipolar I disorder and bipolar II disorder. 

  1. Bipolar I disorder: People with bipolar I disorder experience manic episodes, often lasting at least seven days. During a manic episode, people have a drastic increase in energy that is so disruptive and severe that they require hospitalization. They also may experience depressive moods, which last at least two weeks, and most people experience types of neutral moods. Bipolar I disorder can significantly interfere with relationships and daily activities such as work.
  2. Bipolar II disorder: People with bipolar II disorder experience periods of depression lasting at least two weeks. Unlike bipolar I disorder, people with bipolar II do not experience mania (manic episodes). Instead, they have hypomanic episodes, milder, less disruptive forms of manic episodes. They may experience neutral moods in between intense mood states. People with bipolar II are more likely than those with bipolar I to have healthy relationships and steady jobs. 
  3. Cyclothymia: Cyclothymia, or cyclothymic disorder, is a milder form of bipolar disorder that causes less severe symptoms. People in this group experience hypomania and depressive symptoms for at least two years but do not meet the diagnostic criteria for hypomanic and major depressive episodes.
  4. Other specified and unspecified bipolar and related disorders: People classified in this group have symptoms similar to those with other bipolar disorder types, but they do not fit into one of the categories above/meet the full criteria for diagnosis. 

This article focuses on the more common conditions, bipolar I and bipolar II disorder.

What are mania, hypomania, and depressive episodes?

Before comparing bipolar I and II disorder, it helps to understand more about mania, hypomania, and depressive episodes. 

Mania (manic episode)

A manic episode occurs when an individual is euphoric, impulsive, or irritable most of the time for at least a week. They also feel invincible or have a grandiose sense of self—for example, believing they can play professional sports when they have no experience or can cure cancer (without a medical background). During a manic episode, a person may also have more energy than usual and have at least three of the following extreme changes in behavior:

  • Less need for sleep
  • Talking more or faster
  • Racing, uncontrollable thoughts, or quickly changing topics while talking
  • Easily distractible
  • Increased activity (such as restlessness)
  • Increased risky behavior, such as gambling, reckless driving, shopping sprees, or using drugs or excess alcohol

During a manic episode, symptoms are severe enough to disrupt work and family life and commonly require hospitalization to keep the person safe. In some cases, during a manic episode, some people will experience psychotic features. This means a break from reality. Some examples of psychosis symptoms are delusions, like thinking the government is watching you, or hallucinations, seeing or hearing things that aren’t there.  

Manic episode triggers vary by person. Some examples of triggers include:

  • Lack of sleep
  • Using drugs or alcohol
  • A very stimulating environment or situation (excess noise, bright lights, big crowds)
  • A significant life change like marriage, divorce, or losing a job

Keeping a mood diary can help pinpoint triggers and track how you feel before an episode. Family and friends can also help identify triggers. Learning your triggers can help you prepare for an episode or prevent it from happening. 

Hypomania

Hypomania, or a hypomanic episode, is a milder form of mania. Symptoms are less severe and may last four consecutive days (rather than a week with mania). Symptoms of hypomania are not as disruptive as manic episodes and generally do not cause disruptions to daily life or require a hospital stay. 

Depressive episodes

During a major depressive episode, which lasts at least two weeks, the individual has at least five of the symptoms below, including at least one of the first two symptoms listed:

  • Intense sadness or despair
  • Loss of interest in activities the person usually enjoys
  • Feeling worthless or guilty
  • Fatigue (low energy)
  • Increased or decreased sleep
  • Increased or decreased appetite
  • Restlessness or slowed speaking or moving
  • Trouble concentrating
  • Frequently thinking about death or suicide

What are the differences between bipolar 1 and bipolar 2 disorder?

Bipolar I disorder

People with bipolar I disorder:

  • Have manic episodes that last for at least seven days or are so severe that they require hospitalization. They may also have symptoms of psychosis. 
  • Usually, but not always, have depressive episodes that last at least two weeks. Depressive episodes may occur simultaneously with symptoms of a manic episode. 

Bipolar II disorder

People with bipolar II disorder:

  • Have depressive episodes
  • Have hypomanic episodes that are less severe than manic episodes
  • Do not have manic episodes

A major difference between bipolar I and II is that bipolar I disorder significantly impacts daily life, affecting relationships and work, while bipolar II disorder has less of an effect on daily life. Another key difference is that people with bipolar II disorder always have depressive episodes, but people with bipolar I disorder do not always have depressive episodes.

Differences between bipolar 1 and 2
Bipolar I Bipolar II
Depression Usually (but not required for diagnosis) Yes
Mania Yes No
Hypomania Sometimes Yes
Psychosis symptoms  Possible No
Hospitalization Yes, for severe manic episodes Usually not required
Impact on daily life Significant impact Less impact
Treatment Medication and therapy; medication for psychosis may also be required Medication and therapy

What causes bipolar disorder? 

Although the cause of bipolar disorder is not entirely understood, a brain chemical imbalance is thought to cause dysregulated brain activity. 

There seems to be a genetic component. Up to 90% of patients with bipolar disorder have a family history of bipolar disorder or depression. 

Factors like stress, lack of sleep, and drugs and alcohol may also trigger mood episodes in certain people. 

People with bipolar I disorder often have other mental health conditions, such as anxiety, substance use disorders, or attention-deficit/hyperactivity disorder (ADHD). 

Diagnosing bipolar disorder 1 and 2 

Often, people go more than ten years experiencing symptoms before they get an accurate diagnosis. In the diagnosis of bipolar disorder, women are likely to be misdiagnosed with depression (major depressive disorder), while men are likely to be misdiagnosed with schizophrenia. Bipolar II disorder can be even more challenging to diagnose because it has symptoms similar to depression. The average age of onset of bipolar disorder is 25 years old, but it varies and can occur at any age, even later in life. 

The healthcare professional will perform a physical exam and take a detailed history. They will also order lab or medical tests to rule out other medical conditions. (Bipolar disorder cannot be diagnosed by a blood test or scan, but various tests can help rule out other conditions.) They may conduct a mental health evaluation or refer the patient to a mental health care professional with experience in bipolar disorder. Bipolar disorder is usually diagnosed based on symptoms and medical history, and in some instances, family history. 

A diagnosis of bipolar disorder requires at least one episode of mania or hypomania. Healthcare providers assess symptoms and use the Diagnostic and Statistical Manual of Mental Disorders (DSM) to determine which type of bipolar disorder the patient has. 

Bipolar I disorder diagnosis

A bipolar I disorder diagnosis requires:

  • At least one manic episode 
  • The manic episode was not caused by medication, substance use, or illness

A depressive episode is not required to diagnose bipolar I disorder.  

Bipolar II disorder diagnosis

A bipolar II disorder diagnosis requires:

  • At least one hypomanic episode
  • At least one major depressive episode
  • Neither episode was caused by medication, substance use, or illness

Treatment difference between bipolar 1 and 2

Although there is no cure for bipolar disorder, the good news is that symptoms can be controlled with proper treatment.

For both bipolar I and bipolar II disorder, medication and psychotherapy or cognitive-behavioral therapy are commonly used. It is important to take the prescribed medication as directed, even when feeling well. Mood stabilizers, such as lithium, are the most common medication for bipolar disorder. Individuals with bipolar I disorder who experience psychosis will be treated with additional medication. The healthcare provider will determine the best treatment options based on symptoms, drug interactions, cost, and potential side effects. 

Whether you have bipolar I or II, your doctor will most likely prescribe a mood stabilizer to control episodes of mania or hypomania. Examples of mood stabilizers include:

Many people require a combination of medications. An antipsychotic may be prescribed alone or in combination with a mood stabilizer. Examples of antipsychotics include:

People with bipolar II disorder may also need to take an antidepressant, along with a mood stabilizer. Using a free SingleCare card or coupon to save up to 80% off the cost of your medications. 

In some cases, when medication and therapy are not effective, electroconvulsive therapy (ECT) may be used. This procedure applies an electrical current to the scalp while the patient is asleep (under anesthesia), causing a short, controlled seizure. These ECT-induced seizures are thought to remodel brain signaling pathways. 

Supporting a loved one with bipolar disorder

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), “With proper treatment, along with support and self-care, people with bipolar disorder can live healthy, fulfilling lives.” 

If you have a loved one with bipolar disorder, you can offer support, understanding, and encouragement. Although most patients with bipolar disorder are in therapy, it is also beneficial for family members to seek support. You may want to seek therapy, and you can also ask your loved one’s healthcare provider for local peer support groups or find a support group online. You can also talk to your loved one’s healthcare provider about putting together a crisis plan.