Our body’s defense system is in charge of checking the things that come into contact with us. It labels normal things as ‘safe’ and dangerous things that can harm you (like viruses), as ‘unsafe’. This defense system will protect us from harmful things by making antibodies to attack ‘unsafe’ things.
However, sometimes the defense system may make a mistake by considering something that is safe, as being unsafe, and will attack it. For example, if the skin was stung by a honey bee, the defense system will think the venom from the honey bee is unsafe and will attack it. The chemicals the defense system releases to fight against ‘unsafe things’ are called histamines. Histamines, along with other chemicals, cause the skin to itch, to redden, and to swell.
Histamine makes three major changes on the skin: redness, swelling and itchiness.
