How does this medication work? What will it do for me?

Valproic acid belongs to the class of medications called anticonvulsants. It is used to manage and control of certain types of seizures. It works on the central nervous system (CNS) in the brain to reduce the number and severity of seizures.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?


Each colourless liquid filled, opaque, orange, soft gelatin capsule imprinted "APO 250" in red ink, contains 250 mg valproic acid. Non-medicinal ingredients: ammonium hydroxide, corn oil, FD&C Yellow No. 6, gelatin, glycerin, isopropyl alcohol, methylparaben, n-butyl alcohol, pharmaceutical glaze, propylene glycol, propylparaben, simethicone, synthetic red iron oxide, and titanium dioxide.

Oral solution

Each 5 mL of bright orange-red liquid with a distinctive strawberry aroma contains the equivalent of 250 mg valproic acid, as the sodium salt. Non-medicinal ingredients: artificial strawberry flavor, FD&C Red No. 40, glycerin, methylparaben, propylparaben, purified water, sodium hydroxide, sorbitol, and sucrose.

How should I use this medication?

The recommended dose of valproic acid is based on body weight. The dose of medication is usually started at a low level (15 mg/kg/day) and increased gradually to reduce side effects. The final dose is determined by the control of seizures with a minimum of side effects. The maximum recommended dose is 60 mg/kg/day.

The capsules should be swallowed whole and can be taken with food to avoid stomach upset. Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take valproic acid if you:

  • are allergic to valproic acid or any ingredients of the medication
  • have liver disease or significant reduction in liver function
  • have Alpers syndrome or Alpers-Huttenlocher syndrome, conditions caused by nervous system breakdown
  • have porphyria
  • have certain metabolic disorders (urea cycle disorders)

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal or stomach cramps (mild)
  • diarrhea
  • dizziness
  • headache
  • indigestion
  • nausea
  • sedation
  • vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • abdominal or stomach cramps (severe)
  • changes in hair (hair loss or increased hair on face, chest, and back)
  • continuous, uncontrolled "back and forth" or rolling eye movements
  • hallucinations
  • increase in seizures
  • increasing tiredness and weakness with behaviour changes (extreme irritability, combativeness)
  • nausea or vomiting (continuing)
  • signs of bleeding (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • signs of muscle damage (e.g., muscle pain, tenderness or weakness, or brown or discoloured urine) – especially if you also have a fever or a general feeling of being unwell
  • tremor

Seek immediate medical attention if any of the following occur:

  • signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
  • symptoms of a serious allergic reaction, including angioedema (e.g., hives; swelling of the face, mouth, hands, or feet; and difficulty breathing)
  • signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood clotting: This medication may make it more difficult for the blood to clot. If you take anticoagulant (blood thinning) medications, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Take appropriate precautions and ensure that all doctors involved in your care are aware of all medication use. Tests for blood clotting should take place before any surgery. Platelet count and coagulant tests should take place before starting treatment with valproic acid.

Drowsiness/reduced alertness: Valproic acid may affect the mental or physical abilities needed to drive or operate machinery. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver failure has occurred infrequently for people taking valproic acid, usually during the first 6 months of treatment. Children under 2 years of age who take valproic acid together with other epilepsy medications are at greatest risk (nearly 20 times greater) of developing serious liver problems. These children typically have other medical conditions such as congenital metabolic disorders, mental retardation, or organic brain disease. Liver function tests should take place before starting treatment with valproic acid.

Serious liver problems may be preceded by symptoms such as loss of seizure control, malaise, weakness, lethargy, loss of appetite, and vomiting. People who take valproic acid should tell their doctor at once if they experience these symptoms. Increases in the levels of ammonia in the blood, with or without lethargy or coma, have been reported and may be present despite normal liver function tests.

Pancreatitis: Cases of life-threatening pancreatitis (inflammation of the pancreas) have been reported for both children and adults. These can occur at any time during the use of valproic acid. If you experience signs of pancreatitis such as abdominal pain on the upper left side, back pain, loss of appetite, nausea, fever, chills, rapid heartbeat, or swollen abdomen contact your doctor immediately.

Sedation: Valproic acid may cause sedation, especially when combined with another sedating drug such as alcohol.

Suicidal thoughts: There is a small risk that this medication may result in thoughts of suicide. If you experience these symptoms or any other behaviour change while taking this medication, contact your doctor immediately. Family members or caregivers of people who are taking this medication should contact the person's doctor immediately if they notice unusual behaviour changes.

Pregnancy: There is an increased risk of birth defects for a child whose mother takes valproic acid during pregnancy. Although rare, valproic acid may cause a defect of the spine called spina bifida or slowed or reduced mental development.

Before becoming pregnant, women with epilepsy should speak to their doctor about options for seizure medications. If you become pregnant while taking this medication, contact your doctor immediately.

People who need medications to prevent major seizures should not stop taking them.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking valproic acid it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. As a general rule, women who are taking valproic acid should not breast-feed.

Children: If valproic acid is given to children 2 years old or younger, it should be used with extreme caution and as a single medication. The benefits of seizure control should be weighed against the risk.

Seniors: People over the age of 65 may be more at risk of developing side effects from this medication and may require lower dosages.

What other drugs could interact with this medication?

There may be an interaction between valproic acid and any of the following:

  • acarbose
  • alcohol
  • ASA
  • benzodiazepines (e.g., diazepam, lorazepam, clonazepam)
  • bismuth subsalicylate
  • carbamazepine
  • chlorpromazine
  • cimetidine
  • cosyntropin
  • ertapenem
  • ethosuximide
  • guanfacine
  • HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
  • imipenem
  • irinotecan
  • isoniazid
  • lamotrigine
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • mefloquine
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
  • meropenem
  • olanzapine
  • oxcarbazepine
  • paliperidone
  • phenobarbital
  • phenytoin
  • primidone
  • rifampin
  • risperidone
  • rufinamide
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
  • tolbutamide
  • topiramate
  • tricyclic antidepressants (e.g., amitriptyline, nortriptyline)
  • trihexylphenidyl
  • vorinostat
  • warfarin
  • zidovudine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.