It’s common for people with epilepsy to wonder how long it will take their bodies to adapt to medications. One MyEpilepsyTeam member asked, “Whether you’re increasing or decreasing any of your meds, how long do you feel it takes your body to adjust to the new dosage?”
This question often comes up when a doctor starts you on a new epilepsy medication or changes your dose. There’s no definitive timeline as to how long it will take for a new medication to start bringing you symptom relief — it can sometimes take weeks or months to reach your maintenance dose (the dose you’ll take long term). Many contributing factors are at play, including the type of medication you’re prescribed, the type of seizures you experience, and how well you follow your prescribing guidance.
In this article, we’ll explore how long it can take for antiepileptic drugs (AEDs) to begin working in your body.
Antiepileptic drugs — also known as anti-seizure drugs or anti-seizure medications — are used to treat seizures and epilepsy. They work by reducing the spread of abnormal electrical activity in the brain that causes seizures. Known as seizure propagation, this abnormal activity can affect different parts of the brain and cause a variety of symptoms.
Most AEDs are taken orally (by mouth). Once in the stomach, they’re absorbed into the bloodstream, where they move around the body until they reach the brain. Over time, your liver and kidneys slowly filter out the AEDs and break them down. This is why you have to take more medication after a certain amount of time.
The goal with most AEDs is to maintain a certain level of medication in your blood and nervous system to prevent seizures. You might have to undergo blood tests to see how quickly a medication is removed from your blood.
Although AEDs can be effective in controlling seizures, they can also have side effects. Some common side effects include:
AEDs can affect you in other ways, including mentally and emotionally. They can impair thinking and memory, making it difficult to focus or remember things. They can also cause mood changes, leading to irritability or sadness.
AEDs and epilepsy itself can have a significant impact on your everyday life. It’s important to have access to resources, such as counseling or support groups, to help manage these challenges.
There are many different drugs that your doctor may prescribe to help treat your epilepsy. When choosing which drug or group of drugs to prescribe, your doctor will consider what type of epilepsy you have, as well as other factors such as your age and medical history.
Seizure medications are typically divided into two groups — broad-spectrum and narrow-spectrum AEDs. Broad-spectrum AEDs are meant to treat or prevent seizures in more than one part of your brain. If you experience more than one type of seizure or don’t know what’s causing your seizures, your doctor may put you on a broad-spectrum AED. Examples of broad-spectrum AEDs include:
Your doctor also may prescribe what’s called a rescue AED. These help stop seizures quickly in emergency situations, such as status epilepticus — when a seizure lasts longer than five minutes. Examples of rescue AEDs are diazepam (Diastat AcuDial, Valium) and midazolam (Nayzilam).
It’s important to work closely with doctors and pharmacists to find the best medication and dosage for each individual. They can also help manage any side effects and provide support for the potential social and economic challenges that can come with taking AEDs.
It can take several weeks or months to reach the dose you will take long term, also known as the maintenance dose. Often, your doctor will start you on a low dose, then increase it over time to help your body adjust to the medication so you can achieve seizure control.
Following are some factors that affect how long it may take for an AED to work.
Medication half-life is an important factor to consider when assessing how long it will take for the medication to work. Half-life refers to the time it takes for your body to eliminate half of the medication.
Medications with shorter half-lives need to be taken more frequently. Those with longer half-lives can be taken less frequently and maintain more stable levels in the body over longer periods of time. Taking these medications regularly is essential to maintaining a constant level in the body, which helps control seizures. Still, it can take several months of regular use to tell whether the medication is working.
When increasing the dose of an AED, you can multiply the half-life by five to estimate how long it will take for the new dose to take effect. This means that if the half-life of your AED is 24 hours, you should expect to see a change after about five days.
The form of anti-seizure medication can impact how quickly it starts to work, as different forms reach your bloodstream at different speeds.
For example, some anti-seizure medications come in immediate-release tablet or capsule form. These medications release the drug into your bloodstream quickly after you consume them. Because of this, they can have a relatively rapid onset of action and may start to work within hours of taking the medication.
Other AEDs come in extended- or sustained-release formulations, which release the medication slowly over a longer period of time. These forms can have a slower onset of action and may take longer to start working, but they can provide more consistent blood levels of the medication and may require less frequent dosing.
Finally, some anti-seizure medications come in liquid or injectable forms, which can have different rates of absorption compared to tablet or capsule forms. Injectable options, for example, typically start to work faster and may be used in emergency situations to quickly control seizures.
For some types of seizures, such as absence seizures, medications may work quickly. In these cases, individuals may experience a reduction in seizure frequency within days or weeks of starting the medication. For other types of seizures, it may take several weeks for the medication to build up in your blood and brain to levels that can effectively control the seizures.
The time at which you take your anti-seizure medication can impact how quickly it starts to work and how effective it is at controlling seizures.
For most AEDs, it’s important to take them at the same time each day to maintain a consistent level of the medication in the body. If you miss a dose or take it at a different time than usual, it may change the drug levels in your bloodstream and brain. This may reduce how well your medication works and potentially increase your risk of side effects.
The time of day you take your medication can also impact how quickly it starts to work. For example, some anti-seizure medications may work better if taken before bedtime or in the evening, as some seizures are more likely to occur while you sleep.
Some anti-seizure drugs can also interact with food, so be sure to follow any instructions regarding whether to take the drug with or without food. Taking the medication with food can sometimes slow down absorption. On the other hand, taking medication on an empty stomach can sometimes speed up absorption and lead to a more rapid onset of action.
Everyone responds differently to medication, and there is no one-size-fits-all answer to how long it will take for your anti-seizure drug to work. You should always talk to your provider and ask any questions you have about how quickly your medications will take effect.
Factors such as age, weight, overall health, and other medications can all impact how quickly or effectively the drug works. For this reason, you may need to try multiple medications or combinations of them to find the best treatment option. You may find it helpful to keep an epilepsy diary where you keep track of when you take your medications, the side effects you’re experiencing, and when you have seizures.
It’s important to take your medication exactly as prescribed by your health care provider, as missing doses or stopping medication abruptly can increase the risk of seizures. Check in with your neurologists and pharmacists so they can keep track of any changes or side effects you may be experiencing. They can provide guidance on when to expect the medication to take effect and what to do if it doesn’t seem to be working.
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