It’s been calculated that highly sensitised individuals can react to as little as 1/2000th of a single peanut. In research studies of adults with a known peanut allergy the amount varied from one tiny fragment to two peanuts.

If there is ongoing exposure, even to small amounts, it can take less and less to cause a reaction as time goes by. This is because repeated exposure boosts the immune response, and the IgE antibody levels rise. The size of the allergy skin test is a rough guide to a person’s antibody levels.