Runny Nose in Adults

Common Causes

• Allergies (allergic rhinitis) — Exposure to pollen, dust, or pet dander may trigger histamine release, leading to watery mucus in adults.
• Viral infections — Colds or flu viruses might irritate nasal linings, causing clear then thicker mucus as the body fights back.
• Nonallergic rhinitis — Irritants like smoke or strong smells could cause ongoing symptoms without an allergy.
• Sinus infections (sinusitis) — Blocked sinuses from bacteria or viruses may lead to thick, colored mucus.
• Gustatory rhinitis — Spicy or hot foods might stimulate nerves, resulting in a sudden runny nose.

Learn More

For a full overview of this symptom, including home remedies and when to see a doctor, read our complete guide on Runny Nose.