Reviewed by: HU Medical Review Board | Last reviewed: November 2021 | Last updated: July 2022
Sometimes epilepsy is not controlled with anti-seizure drugs. About 1 in 3 adults and about 1 in 4 children with epilepsy are thought to have drug-resistant epilepsy. That adds up to about 400,000 people in the United States. You may also hear drug-resistant epilepsy called refractory, uncontrolled, or intractable epilepsy.1,2
What is drug-resistant epilepsy?
The International League Against Epilepsy (ILAE) sets the standards for epilepsy treatment. The ILAE says someone has drug-resistant epilepsy if they tried 2 anti-seizure drugs and did not become and stay seizure-free. These 2 drugs may be tried 1 after another or both at the same time.1-3
Some people have epilepsy that is drug-resistant from the start. Others find their epilepsy is better controlled at some times in their life than others.
Reasons for drug-resistant epilepsy
There are 4 main reasons why someone’s seizures may not be controlled:2
- Their diagnosis is wrong and they do not have epilepsy.
- Their treatment is not right for the type of seizure they have.
- Triggers and lifestyle may play a bigger role in their epilepsy and need more control.
- A different dose of their current anti-seizure drugs or other treatments such as surgery are needed.
For example, someone may find their anti-seizure drugs work if they get regular sleep. Another may find they have been misdiagnosed with epilepsy when they really have narcolepsy or panic attacks. One study in England found that about 1 out of 10 people referred to doctors for drug-resistant epilepsy were misdiagnosed.2
Sometimes it takes time to find the right medicine to control a person’s seizures. Some people have been given the wrong anti-seizure medicine. Others find they are taking the right medicine at the wrong dose.
Not all anti-seizure drugs work for all types of seizures. For example:1,4
- Carbamazepine (Tegretol®) often helps with focal (partial) seizures but can make absence and myoclonic seizures worse.
- Ethosuximide (Zarontin®) usually works for absence seizures but does not work for focal (partial) seizures.
- Some people need higher doses of a drug to become seizure-free. Others need lower doses.
Risks for drug-resistant epilepsy
It is hard for doctors to predict who will have drug-resistant epilepsy. More than half of people respond to the first anti-seizure drug they are prescribed. After that, another 1 in 5 becomes seizure-free on the next drug tried. The more anti-seizure drugs that fail, the more likely the person will continue to have seizures.1,2
Other risks of developing drug-resistant epilepsy include having:1
- A large number of seizures before being diagnosed and treated for epilepsy
- Hard-to-treat childhood epilepsy syndromes including early (neonatal) myoclonic encephalopathy, early infantile epileptic encephalopathy, Lennox-Gastaut syndrome, and Rasmussen encephalitis
- Focal (partial) seizures in children
- Family history of epilepsy
- Status epilepticus (a seizure that lasts more than 5 minutes, or 2 or more seizures in a 5-minute period without recovering in between)
- A recent change in anti-seizure medicines
- A history of complex febrile seizures
- A history of recreational drug use
Some studies say that age at first seizure predicts how likely someone will be to have drug-resistant (refractory) epilepsy. In these studies, seizures that begin in late childhood or the teen years seem to be more likely to become drug-resistant. Seizures that begin after age 65 seem less likely to become drug-resistant. However, other studies have not found this to be the case.1
Complications of drug-resistant epilepsy
Drug-resistant epilepsy is serious. People with this type of epilepsy have higher rates of death and injuries due to accidents. It is hard to perform well at school or work with uncontrolled epilepsy. It also leads to more isolation, stigma, fear, depression, and anxiety.1
More research is needed to understand the causes of drug-resistant epilepsy and how to treat it.
In addition to drug-resistant epilepsy, epilepsy complications may also occur. These include: