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Brain tumour side effects

Brain tumours may cause side effects which can have an impact on your quality of life. They can affect different parts of the brain which control different functions. This means that any brain tumour side effects depend on the location, size and aggressiveness of the tumour.  

Here you can find out more information about the common brain tumour side effects. And, you can discover some of the strategies our community has found useful to cope with them. 

Personality changes

Brain tumours can cause personality changes such as anxiety and confusion.

Memory difficulties

Learn how brain tumours can affect memory and get tips for coping.

Communication difficulties

A brain tumour can cause difficulties with understanding or expressing language, or both.


Fatigue is the most common side-effect of brain tumours and their treatment.


Depression can be triggered by a diagnosis, treatment or by the impact on daily life.

Cognition (thinking skills)

Brain tumours and treatments can affect thinking skills, making aspects of daily life difficult.

Seizures (epilepsy)

Up to 60% of brain tumour patients will experience a seizure at least once.

Learning difficulties

It’s estimated that over half of children with a brain tumour will experience a learning difficulty.

Sight problems

Around 28% of people with a brain tumour report a vision problem, find out about sight problems.

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Whether you need more information on brain tumour side effects, or just want to talk to someone, we’re here to help. You can contact our helpful and approachable Support Team.

Brain tumour side effects and their causes

There are lots of different things that can cause brain tumour side effects. And, if you’d like to understand each of the side effects better, the links above will give you more complete information. But, the list below will give you a brief look at some of the things that cause these side effects.

Personality changes

Sadly, brain tumours can cause changes to someone’s personality. This can be because of where the tumour is in the brain, swelling in the brain, some medical treatments, or possibly the emotional side of being diagnosed.

Memory difficulties

People with brain tumours might have difficulty remembering things. If this happens, it could be because of the tumour affecting the parts of the brain that deal with memories. It could also be the effect of the treatment.

Communication difficulties

Brain tumours can sometimes make it hard for people to communicate. They could struggle with language, speech, or understanding. This might be because of the location of the tumour in the brain or the type of treatment being used.


People affected by brain tumours might feel tired, heavy, or weak, or all of these. This can sometimes be because of how the tumour affects the brain or the treatment being used. It could also be the strain of dealing with cognitive difficulties or anxiety, diet and dehydration, pain, seizures, or even higher levels of cytokines, which are immune system proteins.


Understandably, some people who are diagnosed with brain tumours can get depressed. There are lots of things that can cause depression, but it could be because of the tumour affecting the parts of the brain that regulate mood. It could also be because of the diagnosis, which can be a shock, or possibly the way the diagnosis affects the person’s life.

Cognitive difficulties

Brain tumours can sometimes make it hard for people to learn, plan, make decisions, concentrate, and make decisions. This might be because of the location of the tumour or its treatments. But, it could also be because of things that can come with brain tumours, like fatigue, epilepsy, depression or anxiety.


Seizures, or epilepsy, can start because of a brain tumour. This could be because of the brain tumour disorganising the electrical activity in the brain. Or, it could possibly because of the tumour creating a chemical imbalance in the brain.

Learning difficulties

Children who have brain tumours, or have even had them in the past, might struggle to learn things. This could apply to a few different things, like remembering, problem solving, processing, or paying attention. These difficulties could be because of the tumour itself in the brain or some of the other brain tumour side effects, like fatigue.

Sight problems

Brain tumours can cause sight difficulties like dry eyes, abnormal eye movements, light sensitivity, double vision, or loss of vision. This could be because of the position of the tumour in the brain, swelling of the optic disc, pressure on the optic nerve, or possibly the treatment being used.

Coping with brain tumour side effects

For more on how to cope with the individual side effects, please take a look at the information in the links near the top of this page.

But, for a personal account of living with one of the side effects of a brain tumour, you can take a look at this video: