intractable epilepsy

What are the cases of side effects caused by epilepsy drugs?

The drug may have other beneficial effects on the body, apart from the therapeutically effective effects. All medications have side effects, and epilepsy medications are no exception.

However, the types and timing of side effects vary from person to person, and some people do not have side effects. In general, the following are cases where side effects are likely to occur with epilepsy drugs.

  • When you start taking medicine
  • High dose
  • When you suddenly stop taking the medicine at your own discretion
  • Due to an allergic reaction

When taking a medicine for the first time, it is often the case that the dose is gradually increased from a small amount while checking the effect of the medicine and the presence or absence of side effects.

Also, if you suddenly stop taking the drug at your own discretion just because the symptoms have disappeared, the blood concentration of the drug will change rapidly and side effects will be more likely to occur.

Types of side effects seen with antiepileptic drugs

The types of side effects seen with antiepileptic drugs are:

  • Psychiatric symptoms
  • emotional instability
  • Cognitive decline
  • Weight gain

I will explain each in turn.

Psychiatric symptoms

Because epilepsy is caused by abnormal excitement of the cranial nerves, treatments for epilepsy are also designed to act on the cranial nerves. Therefore, the use of epilepsy medications may cause psychiatric symptoms.

For example, a “depressed state” in which one feels depressed and is bound by pessimistic thoughts, which reduces the motivation to act and the feeling of having fun, hallucinations in which non-existent voices are heard, and hallucinations in which non-existent objects are seen occur. There is a “hallucinating delusional state” in which delusions that make you believe that it is not a fact appear.

These side effects are hard to notice on your own and should be noted by family and friends around you.

emotional instability

Apart from depression and hallucinatory delusions, some people have emotional instability.

Due to the characteristics of epilepsy drugs that suppress abnormal excitement in the brain, there are also drugs that have the effect of adjusting mood, and there are some that calm the frustrated mood and others that make the mood depressed.

If the drug works in the wrong direction, it may make you feel more depressed and lead to depression. In addition, you may become frustrated and aggressive, or you may not be able to stop sudden actions and behave abnormally when viewed from the surroundings.

Hyperactivity may also occur in children.

Cognitive decline

Epilepsy medications not only reduce the abnormal excitement of the brain, but can also reduce it to normal functioning.

Ability related to understanding, judgment, memory, calculation, learning, language, etc. is called cognitive function. Deterioration of these functions will cause major problems in daily life such as studying at work or school, and talking with friends and family.

It should be noted that elderly people may be mistaken for dementia.

Weight gain

There is a part of the brain called the appetite center that regulates appetite. Some epilepsy medications stimulate this appetite center.

By stimulating the appetite center, you may get fat because your appetite does not stop.

Conversely, if it acts in a direction that suppresses the appetite center, it may cause loss of appetite and weight loss.

There are various other side effects such as drowsiness, dizziness, nausea, light-headedness, weakness, swelling of the gums (gingival overgrowth), and urinary stones.

Drugs that may exacerbate epilepsy symptoms and seizures

Some epilepsy medications can make or induce epilepsy. It is strange that epilepsy drugs induce epilepsy, but while it works for certain epilepsy, other epilepsy-inducing patterns and overdose can induce epilepsy.


It may induce mild tonic seizures, such as opening eyes during sleep and disturbing exhalation. Please note that it may be left unattended during the day because it is difficult to notice.


May induce absence seizures and myoclonic seizures.

Absence seizures are seizures that cause loss of consciousness for tens of seconds without convulsions.

Myoclonic seizures are seizures in which the muscles of the whole body or some of the limbs contract, and when severe, they may fall or throw what they have.

High concentration phenytoin

Although the frequency of occurrence is not high, it has been reported to increase the frequency of seizures.


Overdose may induce absence seizures.

In addition to the above, there are various epilepsy drugs that induce epilepsy, but if you suddenly stop taking the drug just because you have symptoms, you will have withdrawal seizures, so gradually. It is necessary to reduce it.

How to deal with side effects and how to deal with them

Even if you take epilepsy medicine and have side effects, it is important not to stop at your own discretion and consult your doctor immediately. Stopping taking the drug can trigger seizures.

In addition, if seizures occur repeatedly, it may be difficult to lead a daily life, or the progress of symptoms may be fatal, so even if side effects occur, the balance between the therapeutic effect and side effects You may need to continue taking it while watching.

Even small changes can be a precursor to side effects. Knowledge of the side effects of epilepsy drugs can help you notice even the smallest things.

Talk to your doctor right away if you have any concerns.


Side effects of antiepileptic drugs – Aichi Prefectural Blue Bird Medical Care Center

Hideki Hotta, Shinichiro Hamano, Kiyomi Fukushima (1990) “Weight gain and nocturnal urine due to valproic acid”: Epilepsy research J-STAGE

Emotional Impact of Antiepileptic Drugs-Epilepsy Information Center

Psychiatric symptoms associated with conversion-Epilepsy Center, Osaka University Children’s Survival Hospital

Cognitive function e-health net



September 2023