The use of valproate for migraine or bipolar disorder during pregnancy is contraindicated in the European Union, and the medicines are not recommended for epilepsy during pregnancy unless there is no other effective treatment available. Elderly
Valproate may cause increased somnolence in the elderly. In a trial of valproate in elderly patients with dementia, a significantly higher portion of valproate patients had somnolence compared to placebo. In approximately one-half of such patients, there was associated reduced nutritional intake and weight loss. Overdose and toxicity
Excessive amounts of valproic acid can result in somnolence, tremor, stupor, respiratory depression, coma, metabolic acidosis, and death. In general, serum or plasma valproic acid concentrations are in a range of 20–100 mg/L during controlled therapy, but may reach 150–1500 mg/L following acute poisoning. Monitoring of the serum level is often accomplished using commercial immunoassay techniques, although some laboratories employ gas or liquid chromatography. In contrast to other antiepileptic drugs, at present there is little favorable evidence for salivary therapeutic drug monitoring. Salivary levels of valproic acid correlate poorly with serum levels, partly due to valproates weak acid property (pKa of 4.9).In severe intoxication, hemoperfusion or hemofiltration can be an effective means of hastening elimination of the drug from the body. Supportive therapy should be given to all patients experiencing an overdose and urine output should be monitored. Supplemental L-carnitine is indicated in patients having an acute overdose and also prophylactically in high risk patients. Acetyl-L-carnitine lowers hyperammonemia less markedly than L-carnitine.
The sodium salt of the acid is sodium valproate and a coordination complex of the two is known as valproate semisodium. Medical uses
It is used primarily to treat epilepsy and bipolar disorder. It is also used to prevent migraine headaches. Epilepsy
Valproate has a broad spectrum of anticonvulsant activity, although it is primarily used as a first-line treatment for tonic–clonic seizures, absence seizures and myoclonic seizures and as a second-line treatment for partial seizures and infantile spasms. It has also been successfully given intravenously to treat status epilepticus. Mental illness
Bipolar disorder
Valproate products are also used to treat manic or mixed episodes of bipolar disorder. Schizophrenia
A 2016 systematic review compared the efficacy of valproate as an add-on for people with schizophrenia:

Dopamine dysregulation syndrome
Based upon five case reports, valproic acid may have efficacy in controlling the symptoms of the dopamine dysregulation syndrome that arise from the treatment of Parkinsons disease with levodopa. Migraines
Valproate is also used to prevent migraine headaches. Other
The medication has been tested in the treatment of AIDS and cancer, owing to its histone-deacetylase-inhibiting effects. Contraindications
Contraindications include:

Pre-existing acute or chronic liver dysfunction or family history of severe liver inflammation (hepatitis), particularly medicine related.