Valproic acid belongs to the class of medications called anticonvulsants. It is used to manage and control 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.

The recommended dose of valproic acid is based on body weight. The dose of medication is usually started at a low level (15 mg per kg of body weight per day) to minimize side effects, and increased gradually until seizures are controlled with a minimum of side effects. The maximum recommended dose is 60 mg per kg of body weight per day.

The capsules should be swallowed whole. Do not chew or puncture the capsules. Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons. Valproic acid may be taken with food or on an empty stomach, however taking this medication with food may help to reduce stomach upset.

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, 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 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 systemic primary carnitine deficiency (SPCD) and your carnitine levels are low
• have porphyria
• have certain metabolic disorders (urea cycle disorders)
• are or may become pregnant and there is no suitable alternative treatment for your epilepsy
• are not able or willing to use effective birth control while taking this medication

Valproic acid should not be used by pregnant women if there is a suitable alternative 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.

• diarrhea
• dizziness
• fatigue or tiredness
• headache
• indigestion
• nausea
• sedation
• vomiting
• weakness
• weight gain due to increased appetite

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

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

• changes in hair (hair loss or increased hair on face, chest, and back)
• difficulty reading, speaking, or understanding
• hallucinations (seeing or hearing things that aren't there)
• decreased level of consciousness, increasing tiredness and weakness with behaviour changes (extreme irritability, combativeness)
• nausea or vomiting (continuing)
• not wanting to eat meat or high protein-containing foods
• signs of behavioural problems (e.g., hyperactivity, difficulty concentrating, abnormal behaviour, learning disorders [more common in children])
• 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 kidney problems (e.g., change in the amount or colour of urine, increased urination at night, blood in the urine, swelling in the feet or legs)
• 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 low body temperature (e.g., shivering; slurred speech; slow, shallow breathing; confusion; low energy; memory loss)
• 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
• symptoms of low carnitine levels (e.g., fatigue, muscle weakness, pain)
• symptoms of decreased health of brain cells (brain atrophy; e.g., memory loss, decreased motor skills, seizures, difficulty speaking, reading or understanding)
• tremor
• urinary incontinence

Seek immediate medical attention if any of the following occur:

• increased frequency of seizures or new types of seizures
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• symptoms of Fanconi syndrome (e.g., passing a large amount of urine, feeling thirsty, bone pain, weakness)
• 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
• thoughts of self-harm or suicide

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.

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 the medications you 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, severe seizure disorders accompanied by mental retardation, or organic brain disease. Liver function tests should take place before starting treatment with valproic acid.

Symptoms that can occur before serious liver problems include seizure control, malaise (generally feeling unwell), 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.

Low carnitine levels: Carnitine is a chemical that is made by the body to help turn body fat into energy. Low levels of carnitine in the body contribute to an inability of the body to clear other chemicals, primarily ammonia, out of the body. The resulting build-up of ammonia can be dangerous, causing damage to organs and preventing the body from working as well as it should.

Valproic acid can cause a decreased amount of carnitine in the body and result in liver damage, low blood sugar levels, enlargement of the heart muscle, and muscle damage. If you experience decreased coordination, decreased consciousness, or vomiting, seek immediate medical attention.

Mental health: Some people taking this medication, particularly children, have experienced behavioural changes including aggression, difficulties with maintaining attention, and the development of learning disorders. These changes can also occur in children from the use of valproic acid during pregnancy. If you notice any mental changes while taking this medication, let your doctor know immediately.

Multi-organ hypersensitivity reaction: A severe allergic reaction has occurred on rare occasions for some people with the use of valproic acid, as well as other medications to treat seizures. This reaction involves a number of organs in the body and may be fatal if not treated quickly. Stop taking the medication and get immediate medical attention if you have symptoms of a severe allergic reaction, including fever, swollen glands, yellowing of the skin or eyes, or flu-like symptoms with skin rash or blistering.

Pancreatitis: Cases of life-threatening pancreatitis (inflammation of the pancreas) have been reported for both children and adults. This 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.

Seizures: Some people experience an increase in seizures or new types of seizures when taking valproic acid. If you experience a change in your seizures, contact your doctor as soon as possible.

Stopping the medication: Valproic acid should not be stopped suddenly, as this can cause seizures to increase in frequency and severity. If you need to stop taking this medication, it should be reduced gradually. Talk to your doctor about the best way to stop this medication.

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 serious birth defects for a child whose parent takes valproic acid during pregnancy. Valproic acid may cause a defect of the spine called spina bifida, cleft palate, heart defects, autism, hearing problems, or slowed or reduced mental development. People who could become pregnant must use effective birth control while taking valproic acid. Your doctor may require you to do a pregnancy test before starting this medication to make sure you are not pregnant.

Before becoming pregnant, people with epilepsy should speak to their doctor about other 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. If it is necessary to stop taking this medication, your doctor will advise you of the best way to reduce or change the medication.

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

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other 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.

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.