Lilacs are not poisonous to cats. These plants, or shrubs, are popular in people's gardens and do no harm if pets lick or ingest them.
Lilacs stems, flowers and leaves pose no health threat to cats or dogs. Cats that get into gardens do become ill after ingesting other popular plants such as begonias, daffodils, daisies and ivy. Signs of plant toxicity in cats include vomiting, lethargy, diarrhea and seizures.
A cat that displays any of these signs needs medical attention. The sooner the cat receives treatment after ingesting toxic plants, the better the chance for a positive outcome. Treatment for toxicity includes oral medications, intravenous medications, hospitalization, the induction of vomiting and supportive home care. Homes with cats should be free of toxic plants.