Choice will depend on clinical condition, and should primarily be based on suitability for the patient, rather than safety during breastfeeding.
Whilst sodium valproate  is a suitable choice for use during breast feeding, current  MHRA advice states that it should not used in women of child bearing age unless Pregnancy Prevention Programme is in place, and only if other treatments are ineffective or not tolerated.
Combination therapy may pose an increased risk to the infant, especially when adverse effects, such as drowsiness, are additive.
All infants should be monitored for sedation, poor feeding, adequate weight gain, and developmental milestones. Withdrawal effects may occur in infants if a mother suddenly stops breastfeeding, particularly if she is taking phenobarbital, primidone, or lamotrigine.
Measurement of an infant’s serum level might help rule out toxicity if there is a concern.