People with epilepsy may 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. Depending on the person and the medication, it can take many days or even weeks to reach your maintenance dose (the dose you’ll take long term).

What Are Anti-Seizure Drugs?

Anti-seizure medications (ASMs) — previously called antiepileptic drugs — don’t cure epilepsy. Instead, they’re used to help prevent seizures. ASMs work by lowering electrical activity in the brain that causes seizures.

Most seizure medicines are taken orally (by mouth). Once in the stomach, they’re absorbed into the bloodstream, eventually reaching the brain. Over time, your liver and kidneys slowly filter out the ASMs and break them down. This is why doses need to be taken regularly.

The goal with most ASMs is to maintain a certain level of medication in your blood and nervous system to prevent seizures. Blood tests help show how quickly your body processes your medication.

Side Effects of Anti-Seizure Medications

ASMs can be effective in controlling seizures. But they also have some common side effects, including:

• Drowsiness, dizziness, or unsteadiness
• Blurry vision
• Upset stomach
• Headaches
• Weight changes
• A lowered ability to fight infections
• Mood changes

ASMs can affect you physically, mentally, and emotionally. They can impair thinking and memory, making it difficult to focus or remember things. They can also lead to irritability or sadness. Watch for mood or behavior changes when taking ASMs. Increased risk of suicidal thoughts and behaviors is a rare but possible side effect that requires immediate medical attention.

Note: If you or someone you know needs help, you can contact the 988 Suicide & Crisis Lifeline by calling or texting 988 or chatting online.

Types of Anti-Seizure Medications

There are many different drugs that can help treat seizures. Your neurologist will consider several factors when choosing a treatment, including the type of epilepsy you have, your age, your overall health, and other medications you may be taking.

ASMs are typically divided into two groups: broad-spectrum and narrow-spectrum ASMs.

Broad-spectrum ASMs are used in a wider variety of seizures. 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 ASM.

Common examples of broad-spectrum ASMs include:

• Lamotrigine
• Levetiracetam
• Topiramate

Narrow-spectrum ASMs are used to treat specific types of seizures. Some examples of narrow-spectrum ASMs include carbamazepine and ethosuximide. Other narrow-spectrum medications are also available.

In some cases, your doctor may also prescribe a rescue medication for seizure clusters (also called acute repetitive seizures). Rescue ASMs are used to quickly stop seizures in emergency situations. Examples include diazepam, available as a rectal gel or nasal spray, and midazolam, available as a nasal spray.

Reaching a Maintenance Dose

Your doctor may start you on a low dose first. They can increase it over time to help your body adjust and achieve seizure control.

The following are some factors that affect how long it may take for an ASM to work.

The Medication’s Half-Life

The half-life is 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 often because they maintain more stable levels in the body over longer periods of time. It can take weeks to months to know whether it’s the right fit. It’s essential to maintain a constant level of medication in the body to see if it’s effective or not.

When increasing the dose of an ASM, you can multiply the half-life by five to estimate when the new dose reaches a steady state in your body. This means that if the half-life of your ASM is 24 hours, you should expect to see a change after about five days.

However, this can vary across ASMs, so talk to your doctor and pharmacist about what to expect.

The Form of the Medication

The form of anti-seizure medication can impact how quickly it starts to work. 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. They can have a relatively rapid onset of action, meaning they start working within hours of taking the medication.

Other ASMs come in extended-release or sustained-release formulations. These types release the medication slowly over a longer period of time. They may have a slower onset of action and take more time to start working. However, you don’t have to take them as often to maintain consistent levels in your blood.

Finally, some anti-seizure medications come in liquid or injectable forms. Rates of absorption may be different than tablet or capsule forms. For instance, injections usually work faster and may be used in emergencies to quickly control seizures.

The Type of Seizure Treated

For some types of seizures, medications may work quickly. Some people may have fewer seizures 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.

When You Take Your Medication

Anti-seizure medication timing may impact how quickly it starts to work and how effective it is at controlling seizures.

Most ASMs must be taken 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, the levels in your body will be off, and you may have side effects or seizures.

Some anti-seizure medications may work better if taken before bedtime or in the evening, as certain types of seizures are more likely during sleep.

Anti-seizure drugs can also interact with food in some cases. Be sure to follow instructions on whether to take the drug with or without food. Medications are absorbed more slowly when taken with food versus on an empty stomach.

Ask Your Healthcare Team

Everyone responds differently to medication. There’s no one-size-fits-all answer to how long it will take for your anti-seizure drug to work. Factors such as age, weight, and other medical conditions can affect your experience.

You may need to try different treatment options before discovering what works for you. Try keeping an epilepsy diary to track your medications, side effects, and seizures. Share this information with your healthcare providers to get their feedback and support.

Remember, missing doses or stopping medication abruptly can increase the risk of seizures. Always take your medication as prescribed and reach out to your doctor or pharmacist with any concerns. Seek support from your healthcare providers and a community of people who know what life is like with epilepsy. You’re not alone on this journey.

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