Complications: Epilepsy Drug Side Effects

Reviewed by: HU Medical Review Board | Last reviewed: November 2023 | Last updated: November 2023

Anti-seizure drugs help control epilepsy seizures, but they can also create unwanted side effects. Sometimes these side effects are minor and last a short time. This is most common for the newer medicines, when someone is taking a low dose or only 1 anti-seizure drug.1

For other people, the side effects are long-lasting and impact the ability to learn in school or hold a job. This is most common when taking some of the older medicines, large doses, or multiple anti-seizure drugs.1

There are many drugs prescribed for epilepsy and side effects vary by drug.

Common side effects of epilepsy medications

The most common side effects of anti-seizure drugs can be divided into physical and mental issues. The side effects you get will depend on the drug you are taking. Physical side effects include:1-4

  • Headaches
  • Tiredness
  • Dizziness
  • Blurry vision
  • Changes in sleep
  • Stomach upset (nausea)
  • Weight gain or weight loss
  • Shaking or tremor
  • Hair loss or unwanted hair growth
  • Skin rash
  • Swelling
  • Heart conduction issues

Mental side effects include problems with:1-4

  • Thinking (brain fog)
  • Memory
  • Attention and concentration
  • Finding the right words
  • Changes in behavior
  • Depression, anxiety, agitation, or other mood changes

Many of the most common side effects occur in the first few weeks of taking the medicine. To reduce the chances of these side effects, your doctor may start you on a low dose and slowly increase the amount you take. Eventually, you and your doctor will find the right dose to control your seizures while also minimizing side effects. These common side effects often go away over several weeks or months.

Talk to your doctor right away if you get a rash, vision changes, or have thoughts of killing yourself. These are both rare but serious reactions to your medicine.1

Drug interactions

Some anti-seizure drugs interact poorly with other medicines you might be taking. This may make it harder to manage your other health conditions.

Other prescriptions, over-the-counter drugs, and supplements may make epilepsy medicine more or less effective. This can lead to more seizures or more unwanted side effects. Make sure your doctor and pharmacist are aware of all the medicines and supplements you take to prevent this from happening.1

Birth control, HRT, pregnancy, and breastfeeding

Family planning may be more complicated if you have epilepsy. Some anti-seizure drugs may make birth control or hormone replacement therapy (HRT) less reliable. And, birth control and HRT can make anti-seizure medicine less effective at controlling seizures. This is why some women need to take a higher dose of these drugs to prevent pregnancy or control menopause symptoms.5

Some types of epilepsy and some anti-seizure drugs contribute to polycystic ovary syndrome (PCOS). Having PCOS can make it harder to get pregnant.6

It is important to plan your pregnancies if you have epilepsy. Some drugs need to be stopped weeks or months before getting pregnant to prevent harm to the baby. Other drugs may require a higher dose during pregnancy to remain effective. You will also need to take folic acid during pregnancy.5

Women who are pregnant or nursing often need to make changes to their anti-seizure drugs or dosing. Some of these drugs should not be taken while pregnant or breastfeeding because they can harm the baby.5,7

Long-term side effects of epilepsy medications

Taking anti-seizure drugs long-term can contribute to:4

  • Bone disease (osteopenia and osteoporosis)
  • Liver and kidney damage
  • Bone marrow problems (including aplastic anemia)
  • Gastrointestinal issues (pancreatitis, nausea, vomiting, diarrhea)
  • Skin rashes (rarely life-threatening rashes, namely Stevens-Johnson Syndrome), and Changes in mental health

Bone disease

Anti-seizure drugs may increase the risk of developing osteopenia and osteoporosis. This happens when the epilepsy drugs interfere with how the body processes vitamin D. Vitamin D is important to maintain bone health.8

Osteopenia and osteoporosis are conditions in which there is bone thinning or loss of bone mass. This makes the bones more fragile and break more easily. This risk is highest for those who take multiple anti-seizure drugs for many years.8

People with epilepsy should have regular bone scans and take vitamin D and calcium supplements. This helps counteract the effects of anti-seizure drugs. This may be even more important for women with epilepsy since women are at higher risk of developing bone disease.8

Monitoring for side effects

Anyone taking anti-seizure medicines needs regular follow-up to monitor for side effects. It is common for someone to get blood tests once a year. A complete blood count and complete metabolic panel are common. More frequent follow-up may be needed if the person also has other chronic health conditions such as liver or kidney disease, chronic infections (such as HIV), or cancer.4,5

Never stop taking or change the dose of your anti-seizure medicine without talking to your doctor first.

In addition to drug side effects, other complications may also occur with epilepsy. These include:

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Treatment results and side effects can vary from person to person. This treatment information is not meant to replace professional medical advice. Talk to your doctor about what to expect before starting and while taking any treatment.