Side effects and drug interactions from anti-epileptic drugs

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It is possible for children to experience side effects when on anti-epileptic drugs. These can include physical symptoms, like dizziness, and changes in mood.

Key points

  • Side effects from AEDs can range from sleep disturbance, problems with memory and dizziness to stomach upset, irritability and mood changes.
  • Side effects can be temporary or long-lasting and usually begin when a medication is started or changed.
  • If your child is experiencing severe side effects that interfere with their school or home life, speak to a member of the treatment team about changing the dose or AED.
  • AEDs can worsen an existing condition that is not related to epilepsy. For this reason, always tell your child's doctor about any other conditions or past drug interactions.

Different AEDs have different side effects. Some are more severe and some are less severe.

The side effects of AEDs may take the form of:

  • physical symptoms, including drowsiness, sleep disturbance, dizziness or stomach upset
  • changes or fluctuations in mood
  • problems with learning, concentration, attention or memory
  • behaviour problems, including hyperactivity or irritability
  • occasionally, more frequent seizures
  • rarely, dangerous reactions such as hypersensitivity (allergy) or liver failure.

Children sometimes experience different side effects than adults. For example, the same medication may cause drowsiness in adults while producing hyperactivity and irritability in children. Individual factors play a role as well: two children may react very differently to the same medication. This may be due to genetic differences in how their bodies treat the medication.

Because epilepsy itself may also have effects on learning, behaviour and mood, it can be difficult to tell whether the effects are caused by the AED or by epilepsy. Talk to the treatment team if you are concerned about a particular effect.

Ask your child's doctor or your pharmacist about possible side effects of your child's medication, including how to recognize potential problems.

the information we have about the side effects of AEDs comes from clinical trials and past experience. These tell us which side effects are more or less likely to happen, but they cannot tell us for certain what will happen to your child. The side effects of a given medication are not seen in all children treated with that medication, and it is usually impossible to predict beforehand whether a child will experience a particular side effect. Your child's doctor will consider the benefits and risks of all medications before prescribing one to your child.

Other medical conditions

In some cases, AEDs may worsen an existing condition that is not related to epilepsy. For example, some AEDs may make the symptoms of porphyria worse.

In other cases, an existing condition can interact with an AED to cause a side effect. For example, people with liver disease may have problems metabolizing an AED, causing it to build up to higher levels in the body, which may lead to dose-related side effects.

For these reasons, your child's doctor will need to know about any other medical conditions that your child has, and any drug reactions that they have had in the past.

Coping with side effects

Some side effects are only initial and temporary. They occur when a medication is first introduced and slowly improve. Other side effects will continue as long as the child is taking the medication. Ask your child's doctor or your pharmacist what to expect.

If your child is experiencing side effects that they cannot tolerate or that are interfering with their school or home life, speak to a member of the treatment team. It may be possible to lower the dose, try a different AED with a different side effect profile, or manage the side effects in other ways, such as changing dosage forms.

Dangerous side effects

There are some rare serious side effects that require immediate attention.

If you note any serious side effects, contact your child's doctor or take your child to the nearest hospital emergency department right away. Serious and potentially dangerous side effects include:

  • extreme lethargy or not waking up
  • problems with breathing
  • skin rash or swelling
  • extreme behaviour changes.

Your child is more likely to experience serious side effects if:

  • the AED is started at a high dose, rather than starting with a low dose and gradually increasing it
  • the dose changes rapidly
  • they are taking more than one AED, or an AED and one or more other medications
  • they have had a reaction, such as a rash, to another medication in the past.

Most serious side effects happen at the start of treatment or after a change in treatment. It is important to stay in contact with the treatment team in the early stages of a new treatment. If you are concerned about a side effect at any time, contact your child's doctor or your pharmacist.

Interactions between anti-epileptic drugs and other medications

Typically, anti-epileptic drugs are taken daily to help prevent seizures. Your child may be prescribed another medication, such as an antibiotic for an ear infection, that has the potential to interact with your child’s epilepsy medication. When two or more medications are used together, a clinically significant drug interaction may occur. For example:

  • The newly added medicine may raise the level of AEDs in the body, potentially causing side effects.
  • The newly added medicine may lower the level of AEDs in the body, potentially causing seizures.
  • The AED may reduce the effectiveness of the newly added medicine, including oral contraceptives.
  • The combination of two or more medications may cause unexpected side effects.

For this reason, never give your child any new medication, including non-prescription, homeopathic and herbal medications, unless they are approved by your child’s doctor or reviewed with a pharmacist. Make sure your pharmacist knows about all the medicines your child is taking.

Last updated: February 4th 2010