Some people also report having sore gums or their mouth going numb. This problem is cause primarily from unripe figs, often the case when they are picked too soon and – watch out – figs don’t ripen when stored. Try cutting an unripe fig and you will see a milk like liquid. This contains a proteolytic enzyme called ficin.
So aim for ripe figs and you should be OK every time. Unless you get greedy and eat too many! Ficin diminishes as the fruit ripens, it is there to protect the fruit from animals eating it too soon.
Another way to make sure you aren’t getting ficin is to cut the figs in half and eat just the red part, avoiding the skin and white parts. But bear in mind that ficin contributes to the fig’s laxative properties, so you might be defeating your primary purpose of eating them!