In young adults, valproic acid is usually started at 5 to 12.5 milligrams (mg) per kilogram (kg, about 2.2. pounds) of body weight per day (typically 250 to 750 mg per day, in two to four doses). Each week, the amount can be increased by 5 to 10 mg/kg per day as required, if side effects are not troublesome.

When valproic acid is used alone (that is, as monotherapy), an average long-term dose for adults is 15 to 60 mg/kg per day (750 to 3,000 mg per day). This amount is usually given in two or three doses. Taking more than 4,000 mg per day is seldom recommended.

Patients over age 65 generally require a lower initial dose and particular caution with any increases. They usually need a smaller amount of valproic acid than younger adults.

Children may require higher doses (adjusted for weight) than adults.

The doctor occasionally may suggest checking the level of valproate in the blood to see whether it falls within the range that is usually considered appropriate for treatment ("therapeutic level"). The therapeutic blood level for valproate is generally considered to be 50 to100 mcg/mL (lower for seniors). Whether the amount prescribed needs to be adjusted generally depends on whether seizures or side effects are occurring, however.