seizure on one side

Overview

A seizure on one side happens when abnormal electrical activity starts in a single area of the brain. This can cause symptoms only on one side of the body, such as twitching, stiffness, or odd sensations. These are called focal seizures (or partial seizures). They do not involve the whole brain like generalised seizures.

Seizures on one side are fairly common. Focal seizures are the most common type of seizure in adults. Many people with epilepsy have focal seizures.

Focal seizures can happen at any age, but they are more common in older adults and people with certain brain conditions (like stroke or brain injury). Children can also have focal seizures, especially if they have a brain abnormality or infection.

Symptoms

Common symptoms

• Twitching or jerking in one arm, leg, or side of the face.
• Numbness, tingling, or a 'pins and needles' feeling on one side.
• A strange taste or smell that comes suddenly.
• A feeling of déjà vu (something feels familiar) or jamais vu (something feels unfamiliar).
• Stiffness or weakness in one limb.
• Staring blankly or being unresponsive for a few seconds.

Symptoms in children

• Children may have brief moments of staring or confusion.
• They may describe odd feelings like 'a funny tummy' or 'a weird taste'.
• Sometimes focal seizures cause vomiting or complaints of a strange smell.
• Younger children may not be able to describe their symptoms, so watch for sudden behaviour changes.

Symptoms in older adults

• Older adults may experience confusion or memory lapses without obvious convulsions.
• Focal seizures can be mistaken for signs of dementia or a stroke.
• They may report feelings of dizziness, numbness, or weakness on one side.
• Sometimes the only sign is a brief period of unresponsiveness or staring.

Causes

Main causes

• Epilepsy – a brain condition that causes recurrent seizures.
• Brain infection (meningitis, encephalitis).
• Stroke or brain tumour.
• Head injury (traumatic brain injury).
• Abnormal blood vessels in the brain (arteriovenous malformation).
• Chemical imbalances (low sodium, low blood sugar, liver failure).

Risk factors

• Family history of epilepsy.
• Previous head trauma (including concussions).
• Stroke or other vascular disease.
• Brain infections in the past.
• Alcohol or drug misuse (especially withdrawal).
• Sleep deprivation or high fever.

When to see a doctor

See a doctor urgently if:

• First seizure ever – see a doctor within 24 hours or go to the emergency department.
• Seizure that lasts more than 2 minutes (call emergency services).
• Seizure after a head injury or fall.
• Seizure along with fever or stiff neck.
• Sudden weakness, speech problems, or numbness after a seizure (could be a stroke).

Book a routine appointment if:

• You have been diagnosed with epilepsy and have a seizure despite taking medication – make a routine appointment with your neurologist.
• You notice a change in the pattern of your seizures (different symptoms, longer duration).
• You experience side effects from seizure medication that bother you.
• You are thinking about starting a family and have epilepsy.

Diagnosis

Your doctor will start with a detailed history of the event and ask about your symptoms. They will also perform a neurological exam to check your strength, sensation, and reflexes.

Tests that may be done

• Electroencephalogram (EEG) – records brain activity; can show abnormal patterns typical of seizures.
• Brain imaging (MRI or CT scan) – looks for tumours, strokes, or structural problems.
• Blood tests – to check for infections, chemical imbalances, or genetic conditions.
• Sometimes a longer video-EEG monitoring in hospital if seizures are hard to capture.

What to expect at your appointment

The diagnosis process may take time. You might need to see a neurologist (a brain and nerve specialist). They will want to know exactly what happens during your seizures, so keeping a seizure diary is helpful. Most tests are painless, and you will be supported throughout.

Treatment

Treatment aims to stop or reduce seizures. The right plan depends on the cause, severity, and your overall health. Most people with epilepsy are treated with daily medication.

Self-care at home

• Take your medication exactly as prescribed – never stop without talking to your doctor.
• Get enough sleep – lack of sleep can trigger seizures.
• Limit alcohol and avoid recreational drugs.
• Manage stress with relaxation techniques like deep breathing or yoga.
• Wear a medical alert bracelet so others know you have seizures.

Medical treatments

The main treatment is anti-seizure medication (also called antiseizure drugs or anticonvulsants). Many types are available, and your doctor will choose one based on your seizure type, age, and other health conditions. Sometimes two medications are needed. If medications do not control seizures, other options include a special diet (ketogenic diet) or nerve stimulation (vagus nerve stimulation).

When is surgery considered?

If seizures come from a specific small area of the brain that can be removed safely, surgery may be an option. This is usually considered only after medications have failed. A thorough evaluation with MRI and EEG is needed first.

Living with this condition

Living with seizures means planning ahead. Tell close family, friends, and coworkers what to do if you have a seizure. Avoid activities where a sudden seizure could be dangerous, like driving (unless your seizures are controlled and local laws allow it), swimming alone, or working at heights.

Lifestyle tips

• Maintain a regular sleep schedule – go to bed and wake up at the same time each day.
• Take your medication at the same time daily – use pill organisers or phone alarms.
• Keep a seizure diary: note when seizures happen, how long they last, and any triggers.
• Learn first aid for seizures: time the seizure, protect the person from injury, do not put anything in their mouth.
• If you drive, check your country's rules – many require a seizure-free period of 6–12 months.

Diet and exercise

A balanced diet is good for overall brain health. Some people benefit from a ketogenic diet (high fat, low carb) – but this must be done under medical supervision. Regular exercise like walking, swimming, or cycling is generally safe, but avoid overexertion that could trigger seizures. Always stay hydrated.

Mental health and emotional wellbeing

Seizures can be frightening and may cause anxiety, depression, or low self-esteem. It is normal to worry about when the next seizure will happen. Talking to a therapist or joining a support group can help. If you have thoughts of harming yourself, get help immediately – call your local emergency number or a crisis line.

Prevention

Not all seizures can be prevented, but you can reduce the risk of some causes. Avoiding head injuries (wearing seatbelts, helmets during sports) can help. Treating underlying conditions like stroke risk factors (high blood pressure, diabetes) may lower the chance of developing seizures.

Vaccines

Some brain infections that can cause seizures (like meningitis) are preventable with vaccines. Check with your doctor if you are up to date on recommended vaccines.

Screening programmes

There is no routine screening test for seizures. If you have a known brain condition (like a tumour or arteriovenous malformation), regular check-ups may catch problems early.

Complications

If left untreated

• Seizures may become more frequent or severe.
• Risk of injury during a seizure (falls, burns, drowning).
• Status epilepticus – a seizure lasting more than 5 minutes, which is a medical emergency.
• Memory and thinking problems over time if seizures are not controlled.
• Increased risk of depression and anxiety.

Long-term outlook

With the right treatment, about 7 out of 10 people with epilepsy become seizure-free or have very few seizures. Many people can stop medication after several years without seizures. Even if you need long-term treatment, most people with focal seizures live full, active lives. Work with your healthcare team to find the best plan for you.

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