Abstract: A therapeutic fingernail treatment device which injects active ingredients via a specially-designed nozzle, to remedy fingernail fungus infections. In a preferred embodiment, the device is constructed as a spray nozzle which attaches to the fingernail, and which is enclosed in a sleeve sealed around the fingernail. By developing cyclical high and low pressure conditions in the sleeve, active ingredients are injected into the space between the fingernail and the fingertip, to achieve the desired therapeutic effects. Thus, fingernail fungus infections can be treated and eliminated. Advantages of the invention include conservation of the usage of active ingredients by recycling them, contrary to existing techniques. The use of a sealed sleeve eliminates wastage of ingredients. The provision of a contoured spray nozzle insures increased efficiency by providing good contact between the active ingredients and the entire fingernail area.