Itchiness is the sensation that causes a person the desire or reflex to scratch at their skin. At lower levels, itchiness can occur as a subtle and minor annoyance which is easy to ignore. However, at higher levels, itchiness can become so intense that is incredibly uncomfortable and can even result in the person damaging their skin through repetitive scratching motions. Itchiness is most commonly induced under the influence of heavy dosages of opioid compounds, such as heroin, fentanyl, tramadol, and kratom. This is due to the way in which opioids activate histamine receptors and trigger histamine release. An effective technique for counteracting itchiness in cases of substance use is to take an antihistamine such as diphenhydramine (DPH, Benadryl).