Borderline personality disorder (BPD) can cause a wide range of symptoms, which can be broadly grouped into four main areas.

The four areas are:

• emotional instability (a psychological term for this is affective dysregulation)
• disturbed patterns of thinking or perception (psychological terms for these are cognitive or perceptual distortions)
• impulsive behaviour
• intense but unstable relationships with others

Each of these areas is described in more detail below.

Emotional instability

If you have BPD, you may experience a range of often intense negative emotions, such as:

• rage
• sorrow
• shame
• panic
• terror
• long-term feelings of emptiness and loneliness

You may have severe mood swings over a short space of time. It's common for people with BPD to feel suicidal with despair, and then feel reasonably positive a few hours later. Some people feel better in the morning and some in the evening. The pattern varies, but the key sign is that your moods swing in unpredictable ways.

Disturbed patterns of thinking

There are three levels of disturbed thinking that can affect people with BPD. These are ranked according to severity:

• upsetting thoughts – such as thinking you are a terrible person or feeling you do not exist. You may not be sure of these thoughts and may seek reassurance that they are not true
• brief episodes of strange experiences – such as hearing voices outside your head for minutes at a time. These may often feel like instructions to harm yourself or others. You may or may not be certain whether these are real
• prolonged episodes of abnormal experiences – where you might experience both hallucinations (voices outside your head) or distressing beliefs that no one can talk you out of (such as believing your family are secretly trying to kill you). These types of beliefs may be psychotic (delusions), and a sign you are becoming more unwell; it is important to get help if you are struggling with delusions

Impulsive behaviour

If you have BPD, there are two main types of impulses you may find extremely difficult to control:

• an impulse to self-harm – such as cutting your arms with razors or burning your skin with cigarettes; in severe cases, especially if you also feel intensely sad and depressed, this impulse can lead to feeling suicidal and you may attempt suicide
• a strong impulse to engage in reckless and irresponsible activities – such as binge drinking, drug abuse, going on a spending or gambling spree, or having unprotected sex with strangers; impulsive behaviours are especially dangerous when people are in brief psychotic states, because they may be more likely to act impulsively if their judgement is impaired

Unstable relationships

If you have BPD, you may feel that other people abandon you when you most need them or get too close and smother you.

When people fear abandonment, it can lead to feelings of intense anxiety and anger. They may make frantic efforts to prevent being left alone, such as:

• constantly texting or phoning a person
• suddenly calling that person in the middle of the night
• physically clinging on to that person and refusing to let go
• making threats to harm or kill themselves if that person ever leaves them

Alternatively, you may feel others are smothering, controlling or crowding you, which also provokes intense fear and anger.

You may then respond by acting in ways to make people go away, such as emotionally withdrawing, rejecting them or using verbal abuse.

These two patterns will probably result in an unstable "love-hate" relationship with certain people.

Many people with BPD seem to be stuck with a very rigid "black-white" view of relationships. Either a relationship is perfect and that person is wonderful, or the relationship is doomed and that person is terrible. People with BPD seem unable or unwilling to accept any sort of "grey area" in their personal life and relationships.

For many people with BPD, emotional relationships (including relationships with professional carers) involve "go away!/please don’t go" states of mind, which is confusing for them and their partners. Sadly, this can often lead to break-ups.