How do you stop waking up with phlegm in your mouth in the morning?

Waking up with phlegm in your mouth can be caused by Allergies, post-nasal drip, or dehydration. To reduce this, consider using a humidifier in your bedroom to keep air moist, staying well-hydrated throughout the day, and avoiding allergens like dust and pet dander. Additionally, elevating your head while sleeping may help prevent mucus accumulation. If the problem persists, consult a healthcare professional to rule out underlying conditions.