Rarely, this medication has caused serious (sometimes fatal) liver problems, usually within the first 6 months of starting treatment. Lab tests should be performed before you start treatment and periodically during treatment, especially within the first 6 months, to monitor this side effect.

The risk of serious liver problems is increased in children younger than 2 years, especially if they have an inherited metabolic disorder, severe seizure disorder with mental retardation, organic brain disease, or if they take more than one seizure medication. Talk with the doctor about the risks and benefits of using this medication in children younger than 2 years.

Due to an increased risk for liver problems, people with certain inherited metabolic disorders (such as Alpers-Huttenlocher syndrome) should not use this medication. Children younger than 2 years who might have these disorders should not use this medication. Children older than 2 years who might have these disorders should be closely monitored during treatment with divalproex sodium. Talk to your doctor for details.

This medication has rarely caused severe (sometimes fatal) disease of the pancreas (pancreatitis). This may occur at any time during treatment and can quickly worsen.

Tell your doctor right away if you develop symptoms of liver problems or pancreatitis such as nausea/vomiting that doesn't stop, unusual tiredness, weakness, swelling of the face, stomach/abdominal pain, loss of appetite, dark urine, or yellowing eyes/skin.

Taking this medication during pregnancy can cause birth defects, may lower your child's IQ, and may increase the risk of your child having certain brain/mental disorders (such as autism, attention deficit/hyperactivity disorder). Men and women using this medication should discuss the risks and benefits of this medication, other treatment options, and use of reliable forms of birth control with their doctor. If you are planning pregnancy, or if you or your partner becomes pregnant or may be pregnant, immediately talk to your doctor. If you are taking divalproex sodium only to prevent migraine headaches, this medication must not be used during pregnancy. If you are taking divalproex sodium to treat seizures or mental/mood problems (such as bipolar disorder), do not stop taking this medication unless directed by your doctor. Untreated seizures and mental/mood problems (such as bipolar disorder) are serious conditions that can harm both a pregnant woman and her unborn baby.