Impulsive and compulsive behaviour

Impulsive and compulsive behaviour is a possible side effect of some Parkinson's drugs.

Only a relatively small number of people experience this, but it can have a big impact on the person affected and those around them.

What is impulsive and compulsive behaviour?

Impulsive behaviour

Impulsive behaviour is when a person can't resist the temptation to carry out certain activities.

These are often activities that give an immediate reward or pleasure, such as gambling, eating, shopping, an increase in sexual thoughts and feelings, or 'punding' (continually handling and sorting objects). Some people may experience more than one of these behaviours.

Some people may do an activity without giving any thought to the future or to long-term consequences. For example, someone who has the impulse to shop may buy a new item of clothing even if they can’t really afford it. This behaviour may lead to harmful social, financial or legal consequences.

Compulsive behaviour

Compulsive behaviour is when a person has an overwhelming drive to act in a certain way, often repetitively, to reduce the worry or tension they get from their urge.

Some people continue to act in this way, even if they no longer get any pleasure or reward from the activity. In most cases, this behaviour is out of character for the person experiencing it.

How does this relate to Parkinson's?

Impulsive and compulsive behaviour is related to dopamine levels in the brain. Dopamine is the chemical messenger in the brain that is affected in Parkinson’s.

As well as helping to control movement, balance and walking, dopamine also plays a big role in the part of the brain that controls reward and motivation. This is important, as people affected by impulsive and compulsive behaviour are driven or motivated to do something that gives them an instant reward.

Does Parkinson's medication cause impulsive and compulsive behaviour?

Many Parkinson's drugs – particularly dopamine agonists and, in some cases, levodopa – have been linked to these types of behaviour, although it is not clear exactly how the medications cause the changes in behaviour.

Research has shown that around 17% of people with Parkinson's who take dopamine agonists experience impulsive and compulsive behaviour.

For a small number of people, other types of Parkinson's medications, in particular levodopa, have also been shown to have similar side effects. The research suggests that 7% of people who take these other kinds of medication are affected.

Medications affect people in different ways, but research suggests that you may be more likely to experience impulsive and compulsive behaviour if you are:

  • male
  • a younger person with Parkinson's
  • a single person who lives alone
  • a smoker
  • someone with a history of addictive behaviour
  • someone who has a family history of gambling or alcohol abuse

Remember that not everyone will experience this behaviour, so it should not put you off taking your medication. However, we encourage you to talk to your Parkinson's nurse or specialist about these side effects.

Some changes in a person's behaviour may be positive rather than negative. For example, you may experience a renewed or increased interest in hobbies or sex.

Losing interest in hobbies and sex are symptoms of apathy, which can also affect people with Parkinson's. If you feel you are experiencing apathy, speak to your GP, specialist or Parkinson's nurse.

What types of impulsive and compulsive behaviour are there?

Addictive gambling

This is when someone can't resist the impulse to gamble, even though it could have a serious impact on their personal or family finances.

Gambling is easier to do than ever before – especially online – so it may not always be obvious that someone is doing this.

Some people who have developed an addiction to gambling have told us they would steal money in order to gamble or to finance an expensive lifestyle.


This is a focus on sexual feelings and thoughts. Sexual impulses become more intense and might be felt at inappropriate times and towards people other than a partner. This can be really distressing for the person and those around them.

It may also result in an increase in using the internet to access explicit websites. This may happen in secret, perhaps in the middle of the night.

Some people may experience changes in sexual orientation, or start wearing clothes usually worn by the opposite sex.

There is also a risk that someone will behave in a way that is socially unacceptable, or may even break the law.

Binge eating

Impulsive and compulsive behaviour can drive people to eat large amounts of food in a short period of time. This is because they can't control their appetite, so they could gain a lot of weight.

People with this impulse may eat alone because they're embarrassed or they feel guilty about the amount of food they’re eating.

Obsessive shopping

Some people become obsessed with buying things. They will feel an irresistible need to buy more than they need or can afford. This can lead to financial problems.


This is when someone does things such as continually handling and sorting objects. They may be fascinated with taking technical equipment apart or collecting a type of object.

This behaviour can mean people don't get enough sleep. It can also cause social problems with family or at work.

If someone collects objects or takes machinery apart without knowing how to put it back together, it can also have a big financial impact, as they will need to spend money to buy new objects or replace dismantled appliances or other equipment.

Some people also experience other behaviours, such as compulsive singing, smoking, reckless driving, or walking around for no reason and with no purpose.

Addiction to Parkinson’s medication

When someone has the compulsion to take more medication than is needed to control their Parkinson's symptoms, this is known as dopamine dysregulation syndrome. This is a type of impulsive and compulsive behaviour.

If someone is taking too much levodopa, this can lead to more side effects, such as severe involuntary movements (dyskinesia) and hallucinations.

If a person is taking too much medication and their healthcare professional attempts to reduce it back to the levels they are supposed to take, this may cause unpleasant feelings, anxiety and cravings.

A person may refuse to accept this, sometimes resulting in aggression, secret hoarding or requests for repeat prescriptions.

Some people who are switched to levodopa-based treatment after experiencing impulsive and compulsive behaviour on other medication may develop dopamine dysregulation syndrome. So it's important your treatment is monitored by your healthcare professional.

When should I talk to my doctor or nurse about these side effects?

It's important that you are assessed for any potential risk of impulsive and compulsive behaviour by your healthcare professional before you start taking your medication for Parkinson's.

This can be done using the Impulsive and compulsive behaviour in Parkinson's checklist (PDF, 29KB).

If you are already taking Parkinson's medication, we encourage you to talk to your specialist about these potential side effects, especially if you have a family history of these types of behaviour. This may give you some peace of mind and will help you to monitor any potential changes in your behaviour together.

How do I spot signs of impulsive and compulsive behaviour in someone close to me?

Sometimes people who experience impulsive and compulsive behaviour may not realise they have a problem. So if you are a carer or family member and you notice any unusual behaviour, talk to the person with Parkinson's and seek support from your healthcare professional.

It is important to understand that many behaviours are kept secret, or may not be apparent even to close family and friends. The person experiencing this behaviour may not realise the effect it is having.

NHS guidelines state that healthcare professionals, carers and family members of people with Parkinson's need to monitor behaviour over a long period of time. This is because these behaviours can develop after years of treatment without any problems.

If you’re concerned about someone with Parkinson's, look out for any of the following signs:

  • Have they recently put on weight? There may be a number of reasons for this, but you might want to look for the signs of binge eating.
  • Are they being more protective than usual about their finances?
  • Are they being more secretive, perhaps with phone calls or their use of the internet?
  • Have they started collecting or organising certain objects?
  • Have you noticed them carrying out certain tasks repeatedly?
  • If the person with Parkinson's is your partner, have you noticed an increase in their sex drive or a change in their sexual behaviour, either towards you or anyone else?
  • Are they going shopping more often than usual?
  • Are they spending more money, or have they started to lead a more expensive lifestyle?
  • Are they spending more time than usual on their computer (perhaps on shopping or gambling websites, or websites with sexual content)? This may be during the night or the early hours of the morning, so you may not even be aware this is happening.
  • Are they taking more of their Parkinson's medication than they should?
  • Have you noticed an increase in any aggressive behaviour?

It can be upsetting to realise that this may be happening to someone you love, but remember that this behaviour doesn't reflect badly on them or you.

What should I do if I'm experiencing impulsive and compulsive behaviour, or I think someone else is?

People with Parkinson's, carers, family members and friends should be alert for any changes in behaviour, and work with healthcare professionals to monitor this.

Our Impulsive and compulsive behaviour in Parkinson's checklist (PDF, 29KB) may help during your appointments.

If you think you’re experiencing this behaviour, the first step is to speak to your specialist or Parkinson's nurse. It can be upsetting to realise this is happening to you, but seeking medical advice is the first step to addressing it.

Some of this behaviour may be embarrassing and you may feel uncomfortable talking to a healthcare professional about the difficulties you are having. Remember they will have spoken to others with similar problems before and everything you tell them will be treated confidentially.

If you find it difficult to talk about, try writing your thoughts or questions down and giving them to the healthcare professional you’re seeing. You may prefer to attend appointments with your partner or carer, a friend or a relative, so you are not alone and can discuss the issues together.

If you have any questions about Parkinson's drugs and impulsive and compulsive behaviour call our free confidential helpline on 0808 800 0303.

Can impulsive and compulsive behaviour be controlled?

Yes. Treatment can involve reducing the daily dose of Parkinson's medication, or changing a dopamine agonist prescription to levodopa or another type of medication.

We don't advise anyone to stop taking or to change their Parkinson's medication without the advice of their specialist or Parkinson's nurse. Any changes have to be made slowly and gradually, and should always be carried out and reviewed by a specialist, because of the risk of side effects and withdrawal symptoms.

Dopamine agonist withdrawal syndrome can happen when someone stops taking dopamine agonists very suddenly. It can lead to symptoms such as depression, anxiety and pain.

You may also find other practical measures useful, such as asking a trusted family member to keep your credit cards safe, setting up internet blocks on gambling or explicit websites, and having voluntary 'bans' from bookmakers.

You should also talk to your specialist or Parkinson's nurse about having a general mental health assessment with a qualified professional. This is because certain problems, such as depression, may increase the risk of developing impulsive and compulsive behaviour. Treating mood problems may also help to control the behaviour.

Our Impulsive and compulsive behaviour in Parkinson's checklist (PDF, 29KB) can help you talk about this issue with your specialist or Parkinson's nurse.

Download this information

Impulsive and compulsive behaviour in Parkinson's (PDF, 177KB)

Impulsive and compulsive behaviour checklist (PDF, 26KB)

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This information is being updated

We review our information every 3 years to make sure it is still accurate. As part of this process we are currently updating this page. Please check back soon for the latest version.


"I was becoming happier each day, and with that I started buying more and more things."

We hear from 3 different people on how impulsive and compulsive behaviours affected their lives. 

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Helpline and local advisers

Our helpline and Parkinson's local advisers are here to answer any questions you have about impulsive and compulsive behaviour.

Call us on 0808 800 0303.

Helpline and local advisers
Angela, who works for the helpline, answering a phone call

Last updated June 2015. We review all our information within 3 years. If you'd like to find out more about how we put our information together, including references and the sources of evidence we use, please contact us at [email protected].