The acute stage of an inflammation; pregnancy; scorbutus and purpura; infancy; debility; are conditions rendering their use improper and injurious.

The strangury produced by blisters is lessened by the free use of diluent drinks, and is relieved when it occurs by an enema of laudanum or the hypodermatic injection of a minute quantity of morphine. A decoction of uva-ursi freely drunk will, it is said, prevent strangury, but the effect of this remedy is, probably, not greater than that of an ordinary diluent.

The method of "firing" is sometimes very beneficial in neuralgia, spinal irritation, myalgia, etc. The effects can be regulated by the temperature of the hammer, and by the duration of the contact with the skin, and may vary in severity from the mildest rubefaction to vesication, and even destruction of the skin.