A previously healthy 7-month-old child was treated with homeopathic preparations of thuja, a potentially convulsant compound, for the purpose of providing a calming effect around times of immunizations. The child developed eight generalized tonic-clonic seizures with no other obvious cause, in the context of normal electroencephalograms and a normal brain magnetic resonance imaging scan. Seizures stopped after discontinuation of thuja and brief treatment with phenobarbital. The epileptogenic potential of plant-derived essential oils and other herbal remedies should be recognized by practitioners providing neurologic care to children.