The common cold is generally mild and self-limiting with most symptoms generally improving in a week. Half of cases go away in 10 days and 90% in 15 days. Severe complications, if they occur, are usually in the very old, the very young, or those who are immunosuppressed.
Types of sick sinus syndrome and their causes include: 1  Sinoatrial block. Electrical signals move too slowly through the sinus node, causing an abnormally slow heart rate. 2  Sinus arrest. The sinus node activity pauses.  Bradycardia-tachycardia syndrome.
Nasal congestion from a cold, allergy, sinus infection, or poor air quality is the most common cause of anosmia. Other anosmia causes include: 1  Nasal polyps -- small noncancerous growths in the nose and sinuses that block the nasal passage.  Injury to the nose and smell nerves from surgery or head trauma.