Poisoning is a status effect acquired either through touching a Crown of Thorns Starfish, Sea Urchin, Sea Snake, skinning or touching an alive Lionfish, or by being bitten by a Snake. Poisoning can only be cured by an Antidote consumable.
Without the antidote, it will slowly deplete Health over three days. If you were otherwise healthy, and remain well fed and hydrated, it is possible to survive.
The cure is made from 2 pipi and a coconut flask so always keep a eye out for it. They spawn in the patches of vines/plants in the sand. They have yellow flowers.