Symptoms of concussion

What is a concussion?

A concussion is a mild traumatic brain injury that occurs when the brain is subjected to a strong impact or sudden movement. This can happen due to a fall, a traffic accident, sports, or a blow to the head.

Although the concussion is classified as mild, this does not necessarily mean the symptoms are mild. For some, they last only a few days, while others find that they affect their daily life for weeks or months.

Most concussions occur without loss of consciousness, and a normal CT or MRI scan does not rule out a concussion.

What happens in the brain during a concussion?

When the head or body is subjected to a strong impact, the brain is set in motion inside the skull. This leads to a temporary disruption of the brain's normal function.

In the first hours and days after the injury, a series of changes occur in the brain. Nerve cells release signaling substances, energy consumption increases, blood flow changes, and the brain uses extra resources to restore normal balance. At the same time, the long nerve connections between brain cells can be temporarily affected.

It is this temporary imbalance that can lead to symptoms such as headache, dizziness, fatigue, difficulty concentrating, and sensitivity to light or sound.

For the vast majority, the brain gradually restores balance over the first few weeks, but the speed varies from person to person.

Symptoms of a concussion

Concussion symptoms vary from person to person. Some experience only a few symptoms, while others are affected in several areas at the same time.

Physical symptoms

The most common physical symptoms are:

• Headache or pressure in the head
• Dizziness or balance problems
• Nausea or vomiting
• Blurred or double vision
• Sensitivity to light
• Sensitivity to sound
• Fatigue and lack of energy
• Neck pain

Cognitive symptoms

A concussion can also affect the brain's ability to process information.

This can manifest as, among other things:

• Difficulty concentrating
• Memory problems
• Slower thinking
• Difficulty finding words
• The experience of "brain fog"
• Confusion or disorientation

Many describe it as a feeling that the brain is working slower than usual.

Emotional symptoms

It is also common to experience emotional symptoms after a concussion.

These can include:

• Irritability
• Mood swings
• Anxiety or worry
• Feeling down
• Short temper
• Feeling overwhelmed

These symptoms are common and do not necessarily mean that you have a mental health disorder. They are often a natural reaction to both the injury and the limitations it may cause.

Sleep problems

Many people experience changes in their sleep after a concussion.

Some have difficulty falling asleep, while others sleep significantly more than usual. Sleep problems can contribute to worsening other symptoms such as headaches, fatigue, and difficulty concentrating.‍

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Can concussion symptoms appear later?

Yes.

Symptoms usually appear within the first few hours or the first to second day after the injury, but for some, they develop gradually over several days. As a rule of thumb, concussion symptoms occur within seven days of the injury.

This is partly because the biological changes in the brain develop over time, and because the body in the acute situation may be affected by adrenaline and other stress hormones, which temporarily mask the symptoms.

If you develop a headache, dizziness, nausea, or other symptoms in the days following a blow to the head, you should contact a doctor for an assessment.

Is it normal for symptoms to fluctuate?

Yes.

One of the most characteristic features of a concussion is that symptoms can vary from day to day or even from hour to hour.

You may experience days where you feel almost recovered, followed by days where the headache or fatigue flares up again.

This does not necessarily mean that your condition has worsened.

Often, it is a sign that the brain has been subjected to more strain than it could handle at that time. The strain can be physical, mental, or social, and therefore treatment is often about gradually finding an activity level where symptoms are only minimally affected.

How long do concussion symptoms last?

This is one of the questions we are asked most often.

The short answer is that it varies from person to person.

For most people, symptoms begin to subside gradually over the first few days, and many are symptom-free within two to four weeks. However, this does not mean that symptoms necessarily improve a little every single day. It is completely normal for them to fluctuate along the way.

Some experience an uncomplicated recovery, while others need more time before the brain can once again handle the stresses of everyday life without reacting with symptoms.

There is no one-size-fits-all timeline. Factors such as previous concussions, migraines, stress, sleep, and overall load can affect how quickly you recover.

When symptoms do not go away

For some people, symptoms last longer than expected.

If you continue to experience symptoms after four weeks, it may be relevant to get a more specialized assessment.

This does not necessarily mean that a new injury has occurred or that the brain cannot recover. Often, there are several different factors that contribute to maintaining the symptoms. Therefore, a good assessment is not just about the brain, but also about factors such as sleep, headaches, neck issues, stress, physical activity, worries, and daily functioning.

Read also: Long-term effects of concussion

When should you seek specialized help?

Most people with a concussion are well-supported by their own GP and the natural recovery that occurs in the first few weeks.

However, a specialized assessment may be relevant if:

• symptoms last more than four weeks
• symptoms worsen instead of gradually improving
• headaches, dizziness, or fatigue limit your daily life
• you have difficulty managing work or studies
• you are unsure how to return to activity
• you find that symptoms keep flaring up

The sooner you gain a better understanding of what affects your symptoms, the easier it often is to create a plan that suits you individually.

Concussion treatment

There is no single treatment that helps everyone with a concussion.

Treatment depends on which symptoms you have, how long they have lasted, and how they affect your daily life.

Previously, total rest in a dark room was often recommended. Today, research shows that most people benefit more from relative rest for the first 24-48 hours, followed by a gradual and controlled return to physical, mental, and social activity.

For people with long-term symptoms, treatment may include:

• gradual increase in physical activity
• treatment for headaches or migraines
• management of dizziness and balance issues
• advice on workload in work or studies
• treatment for sleep problems
• support for managing anxiety and uncertainty
• interdisciplinary treatment when multiple symptoms interact

The goal is not to push the brain back to normal faster. The goal is to create the best conditions for it to gradually regain its normal function.

Read more about our concussion treatment → (internal link to treatment page)

Good advice for the first period after a concussion

There is a lot you can do yourself to support the brain's recovery.

The first few days are about finding a good balance between activity and rest.

For example, it can be a good idea to:

• get a good night's sleep
• take breaks throughout the day
• avoid activities that significantly worsen symptoms
• start with light physical activity when symptoms allow
• gradually return to work, studies, or school
• accept that symptoms may fluctuate along the way

Many people feel uncertain when symptoms flare up. This is often a natural part of the process and does not necessarily mean you are back to square one.

Frequently asked questions

Can you have a concussion without losing consciousness?

Yes.

The vast majority of concussions occur without loss of consciousness.

Can symptoms appear the day after?

Yes.

Symptoms typically appear within the first few hours or the first to second day, but for some, they develop gradually over several days. As a rule of thumb, symptoms occur within seven days of the injury.

Is it normal to feel worse after activity?

Yes.

Many people find that symptoms temporarily increase after physical or mental exertion. This is a common part of a concussion and does not necessarily mean you have damaged your brain. Often, it is about finding an activity level where symptoms are only affected to a limited extent.

When can I start exercising again?

That depends on your symptoms.

Most people can start with light physical activity once the initial acute symptoms have subsided. The exertion should then be increased gradually and adapted to how your body reacts.

When should I contact a specialist?

If your symptoms persist beyond four weeks, or if they significantly affect your daily life, work, or studies, it may be relevant to get a specialized assessment.