Anticonvulsant Drugs

Drugs used to prevent and treat epileptic seizures and other types of seizures

Common drugs


  • Clonazepam

  • Diazepam

  • Lorazepam

    Other anticonvulsant drugs

  • Carbamazepine

  • Ethosuximide

  • Gabapentin

  • Lamotrigine

  • Phenobarbital

  • Phenytoin

  • Primidone

  • Sodium valproate

  • Topiramate

Anticonvulsant drugs are mainly used to prevent recurrent seizures caused by epilepsy and as an emergency treatment for prolonged seizures. Left untreated, prolonged seizures may cause brain damage. Rarely, an anticonvulsant drug is used for seizures not due to epilepsy, such as febrile convulsions, which can occur in children. Some anticonvulsant drugs are used to treat pain due to nerve damage, such as trigeminal neuralgia, which causes severe pain on one side of the face.

How do they work?

Anticonvulsants have a direct effect on electrical activity in the brain. A seizure occurs when excessive electrical activity spreads from one part of the brain to other areas, causing uncontrolled stimulation of nerves supplying many parts of the body. Anticonvulsants reduce these abnormally high levels of electrical activity and thereby prevent or reduce the muscle spasms that are characteristic of a seizure. The mechanism by which anticonvulsants relieve nerve pain in disorders such as trigeminal neuralgia is not clearly understood.

How are they used?

If you have recurrent seizures, you are likely to need anticonvulsants for a prolonged period to reduce the frequency and severity of your seizures or, if possible, to prevent them altogether. Your doctor will initially prescribe a single drug that is appropriate for the type of seizure that you have. For example, if you experience absence (petit mal) epileptic seizures, in which brief periods of detachment from reality occur, your doctor will usually give you either ethosuximide or sodium valproate. If seizures are tonic-clonic (characterized by uncontrolled movement of the limbs and trunk) or partial (involving minor twitching movements), your treatment may be with sodium valproate, lamotrigine, or carbamazepine. Drugs such as gabapentin may be used if other anticonvulsants do not control seizures or cause severe side effects.

If a seizure is prolonged, diazepam may be given by intravenous injection, or as a liquid that is administered into the rectum. Once the seizure has been brought under control, intravenous infusions of phenytoin or another drug may be given for a few hours afterwards to prevent seizures from recurring.

The dose of an anticonvulsant is adjusted so that the drug is effective without causing unwanted side effects. You may find that you have occasional seizures while taking anticonvulsants. If this is the case, your doctor may try another drug, either as an alternative or as an additional treatment.

If you have epilepsy you will probably be given a card, bracelet, or pendant giving the details of your condition and treatment. It is advisable to carry this identification with you at all times for others to refer to if you have a seizure.

Diazepam in liquid form may also be given into the rectum during an isolated seizure that is not due to epilepsy, such as a febrile convulsion. Trigeminal neuralgia may need long-term treatment with an oral anticonvulsant.

What are the side effects?

Anticonvulsants can affect memory and coordination and may induce lethargy and impair concentration. You should consult your doctor immediately if you develop signs of a hyper-sensitivity reaction, such as rash, fever, mouth ulcers, and swollen glands, or develop an infection, because some anticonvulsants reduce the effectiveness of the immune system. If you are planning to become pregnant, you should also arrange to see your doctor to discuss your treatment needs during pregnancy.


  • If you are taking anticonvulsants, you should consult your doctor immediately if you develop a rash, fever, mouth ulcers, swollen glands, sore throat, bruising, or bleeding.

  • Do not stop taking or alter the dose of an anticonvulsant without first consulting your doctor. Stopping the drug abruptly could cause withdrawal symptoms and a recurrence of the original problem.

  • Anticonvulsants can harm a developing fetus. If you are planning a pregnancy, you should discuss this with your doctor.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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