Skin is a protective covering meant to guard the internal systems from infection. When skin develops a break, your body will take measures to isolate the break and fight bacteria by forming a film or crust. This is true regardless of what caused the break in the skin. A crusty bump can be the result of many conditions. Allergies cause a skin rash known as dermatitis, hair follicles fill with dead skin cells and oil to form folliculitis, an infection of the pore. Even dry skin can form a type of crust. Treat the area with standard first aid to heal the skin. Once you have the situation under control, you can take measures to determine the cause of the irritation.
Wash the afflicted area with warm water and soap. If possible, avoid using a cloth and just use your hand. Fabric may further irritate the skin. Dampen the area by spraying or dripping water over the bumps or hold the skin under a running tap. Place a small amount of soap on your fingertips to cleanse the sore. Rinse off the soap debris and any dirt or crust from the irritation.
Examine the clean area of skin. Look for red streaking, bruising or swelling. If you have any of these symptoms or feel sick or feverish, see your doctor immediately. Try to determine the cause of the rash. For instance, is it an allergic reaction or a bug bite? Think about the time before the rash started, were you exposed to poison ivy or anything that might cause irritation? Have you been around anyone with chicken pox?
Apply an antibiotic ointment to the area if you cannot determine the cause. A break in the skin is open to bacteria. The ointment will protect the area. Apply the ointment to any area with discharge, pus or an open sore. If the skin is itchy, apply a hydrocortisone cream or ointment if the area does not have discharge or an opening in the skin. Itchy skin with an open sore may need both medicines.
Monitor the region for one or two days. Clean it again if the crust reforms. If after one to two days, there is no improvement, go to the doctor, you may need oral antibiotics. If the rash becomes chronic, meaning that it heals and then breaks out again, see the doctor. Mild skin irritation with an indeterminate cause may heal on its own, once it is clean.