Most pharmacies carry it, Walmart where the antacids are.
Another reason I like Activated charcoal I can use it and I give it to my dogs when they eat something they shouldn't[you know how dogs are]
Epsom salt is also used as a flush if ingested a toxin but it can dehydrate them. I rec Activated charcoal that is all I have ever used.
https://www.backyardchickens.com/threads/flushes-for-aiding-in-toxin-removal.700526/