The affected region will most likely be red, swollen, and heated. You could see a pus-filled blister. If the paronychia has been present for a long period, the nail may change color. It could not have its regular form, or it can appear to be pulling away from the nail bed. Paronychia can be caused by any of the following conditions: Inflammatory diseases such as lichen planus or psoriasis. These conditions are treated with medications or light treatments (phototherapy). Nail infections. The skin around your nails functions as a kind of filter that helps protect you from bacteria found in your environment. When this protective mechanism is compromised, such as by cutting your nails too short, you put yourself at risk for developing skin infections under your nails. Prickly heat. This condition is characterized by red bumps that feel like small pimples and that are usually located on the face or upper body. Prickly heat can be caused by allergies or by using synthetic fabrics such as polyester or nylon clothing. The skin cells of people who suffer from prickly heat are damaged when they come into contact with chemicals used in these clothes. Smoking. Smoking is one of the most common causes of paronychia. Smoking reduces blood flow to the skin, causing it to become red, swollen, and sometimes painful.