Dry, crusty mucus in the nose can be caused by upper respiratory infections, the common cold or rhinitis, which is inflammation in the nasal cavity lining, according to the Children's Health Network. Allergies, both seasonal or perennial, also can cause dry, crusty mucus to form.
Dry and crusty mucus forms when infections and cold viruses are spread from person to person through sneezing, coughing and hand contact, according to the Children's Health Network. Environmental changes also cause mucus to form, especially during harsh temperatures when people breath cold air, a condition known as vasomotor rhinitis. Cold temperatures cause the nose to run and dry up approximately 15 minutes after returning to warmer temperatures.
Decongestant nose drops or sprays used excessively can cause dry and crusty mucus to form, according to the Children's Health Network. As a result, chemical rhinitis develops, and the nose is often dry, stuffy and crusty.
Over-the-counter saline nasal sprays and mists are recommended to diminish dry and crusty mucus and reduce nasal congestion, according to the American Academy of Otolaryngology. Some medications for anxiety and depression may contribute to dry mouth and nasal cavities. It is important to treat nasal congestion, symptoms of allergies and rhinitis to prevent lung issues and problems from worsening.