Lidocaine, xylocaine, or lignocaine is a common local anesthetic chemical used in surgeries. Lidocaine is extremely effective used topically to relieve itching, burning and pain from skin inflammations. Sufferers of Eczema can get relief from itching from Lidocaine cream. Opiate use also increases histamines which triggers the itching reaction rapidly, on higher doses this itching side effect can become more than an annoyance and even lead to infected skin (from scratching). Lidocaine cream at higher strengths is an effective counter to these side effects on top of anti-histamine use.
Most creams come with a small amount of Lidocaine which is not effective for the type of under the skin itching Eczema (and other related skin ailments) and Opiate use causes.