If a gerbil is allergic to nuts how long would it take to have a reaction
It may take about two-three days to show the reaction depending on its immune system. If you notice it has a running nose, then that could be an indication that it has the allergy. You can however, consult a vet for more advice.
Well think about people and their reaction
It depends on how severe of an allergy it is. If it is a mild one it can take a while to show.