When I was a kid my father made me help him in his lobster boat during the summers.
Ichthammol was the only thing that would draw out the fish poison in my hands and fingers when I would get poked with old rotten fish bones.
The finger/s would swell up and nothing the doctor prescribed would work.
Which included soaking in Epsom Salt and some other stuff.
One day my mother pulled a tube of Ichthammol from the medicine cabinet and it worked like a charm.