Table 2.

Main side effects of valproic acid

GI disorders: an increase of liver enzymes is common, particularly in early treatment, and it may be transient. Nausea and diarrhea occur frequently at the beginning of treatment, but disappear after a few days without discontinuing treatment. Rare cases of pancreatitis have been reported

Nervous system disorders: transient side effects such as dizziness, headache, tremor, diplopia and sedation have been evaluated and they can lead to the reduction or the discontinuation of the drug

Weight gain: being overweight at the beginning of treatment may be a significant predictor of further weight gain with VPA

Blood dyscrasias: different studies demonstrated the association of VPA with pro and anticoagulatory effects and they are dose-dependent

Endocrinological disorders: there is a correlation between hypothyroidism and treatment with VPA in monotherapy; moreover, VPA increases the synthesis of Testosterone and decreases its conversion to Estradiol, leading to the PCOS with amenorrhea and irregular periods

Hair loss: it is usually transient and sometimes dose-related. Regrowth normally begins within 6 months after the end of the therapy

Hypersensitivity: this effect is rare and dose, time, frequency-independent

Teratogenicity: despite VPA can induce teratogenic effects during pregnancy, United States Food and Drugs Administration considers acceptable the risk/benefit ratio. The most common teratogenic effect is the delay/impaired development

VPA: Valproic acid; PCOS: Polycystic ovary syndrome.