10 Reasons Why Your Cold May Not Go Away

4. You may have chronic postnasal drainage

The glands in your throat and nose are constantly making mucus, but you don’t usually notice it as it mixes with saliva and you swallow it. However, when your body produces more mucus than normal or when it’s thicker than usual, it becomes more noticeable.

The excess can run down the back of your nose to your throat—that’s postnasal drainage. According to doctors, if you have a productive cough with white or clear phlegm that persists, it may be due to chronic postnasal drip, which usually worsens at night when you’re lying down. Postnasal drainage is common after a cold, but it can also be triggered by weather changes, allergies, and other external factors.