Contraindicated with hypersensitivity to barbiturates and primidone, porphyria, lactation (somnolence and drowsiness may occur in breast-feeding newborns).

Use cautiously with pregnancy (association between use of antiepileptics and an elevated incidence of birth defects; however, do not discontinue antiepileptic therapy in pregnant women who are receiving such therapy to prevent major seizures; discontinuing medication is likely to precipitate status epilepticus, with attendant hypoxia and risk to both mother and fetus; to prevent neonatal hemorrhage, primidone should be given with prophylactic vitamin K₁ therapy for 1 mo before and during delivery); sleep apnea, depression, history of substance abuse, renal or hepatic impairment.