Post-nasal drip is often caused by viral or bacterial infections, but can also be due to allergies or irritation. The most common causes of post-nasal drip are:
Viral Causes
Viruses are one of the most common causes of post-nasal drip. Viruses that can lead to post-nasal drip include:
- Common cold
- Influenza
- Respiratory syncytial virus (RSV)
- Rhinovirus
- Coronavirus
When you get a viral infection like a cold, your body produces excess mucus as a way to try to flush out the virus. This excess mucus drips down the back of your throat, leading to post-nasal drip.
Bacterial Causes
Bacterial infections can also cause post-nasal drip. Some examples include:
- Sinusitis – Often caused by bacteria like Streptococcus pneumoniae or Haemophilus influenzae
- Strep throat – Caused by Streptococcus bacteria
- Pertussis (whooping cough) – Caused by Bordetella pertussis bacteria
Bacterial infections stimulate the body’s immune response, which causes increased mucus production. The excess mucus accumulates in the nose and sinuses and drips down the throat.
Allergies
Allergic rhinitis, also known as hay fever, is another common cause of post-nasal drip. When you breathe in allergens like pollen or dust, it triggers an allergic reaction. This causes inflammation in the nasal passages and increased mucus production. The mucus then accumulates and drips down the throat.
Irritants
Irritants like smoke, pollution, dry air, or chlorine in swimming pools can also irritate the nasal lining and cause post-nasal drip. The irritants trigger increased mucus production as a protective response. This mucus then collects in the back of the throat.
How to Tell if Post-Nasal Drip is Viral or Bacterial
It can sometimes be difficult to determine if post-nasal drip is caused by a virus or bacteria based on symptoms alone. However, there are some clues that can help differentiate between the two:
| Viral Post-Nasal Drip | Bacterial Post-Nasal Drip |
|---|---|
| Starts with cold/flu-like symptoms (runny nose, congestion, sneezing, sore throat) | Symptoms get progressively worse over time |
| Low-grade fever (less than 101°F) | High fever (over 101°F) is common |
| Green or yellow mucus may be present | Thick, dark yellow or green mucus |
| Sinus pain/pressure less common | Facial pain and sinus pressure more common |
| Cough is mild or absent | Cough is common, may be severe |
| Symptoms improve in 7-10 days | Symptoms persist beyond 10 days without improvement |
As shown in the table, viral post-nasal drip is more likely to start suddenly with cold symptoms while bacterial tends to get worse over time. Thick, colored mucus, high fever, severe cough, sinus pain and persistent symptoms also point more to a bacterial cause.
How to Find Relief from Post-Nasal Drip
Whether viral or bacterial, post-nasal drip can be annoying and uncomfortable. Here are some tips to help find relief:
- Use saline nasal sprays or rinses – This helps thin mucus and flush out irritants.
- Try over-the-counter medications – Antihistamines, decongestants and cough suppressants can provide symptom relief.
- Use a humidifier – Adding moisture to the air can help loosen thick mucus.
- Drink plenty of fluids – Staying hydrated helps thin out mucus.
- Get extra rest – This allows your body to focus energy on fighting infection.
- Avoid irritants like smoke, dust or strong scents – This minimizes added nasal irritation.
If post-nasal drip symptoms are severe or last beyond 10 days, see your doctor. They can determine if antibiotics are needed for a bacterial sinus infection. For chronic cases, prescription nasal sprays or allergy treatment may be recommended.
When Post-Nasal Drip Might Signal a Bigger Problem
While post-nasal drip is most often caused by a temporary viral or bacterial infection, persistent symptoms could potentially indicate another health condition. See your doctor promptly if you experience:
- Frequent or chronic post-nasal drip lasting more than a few weeks
- Blood in mucus
- Severe pain or pressure in the sinus area
- Fever over 101°F that lasts more than 3 days
- Severe headaches or facial pain
- Vision changes
- Swollen eyelids or eye swelling
- Green or brown nasal discharge
These types of symptoms could potentially indicate a more serious issue like a severe sinus infection, structural abnormality in the nose or throat, or rarely, a tumor or other condition. It’s important to get evaluated by an ENT (ear, nose and throat) doctor to determine the underlying cause.
When to See a Doctor
You should make an appointment with your doctor if:
- Symptoms last more than 10 days without improvement
- You have a high fever over 101°F
- Your symptoms are severe or worsening rapidly
- You have recurrent or chronic post-nasal drip
- You have blood in your mucus
- You have a weakened immune system
- You have asthma, COPD, or another lung disease
Seeking prompt medical treatment is recommended if you have any symptoms or risk factors that point to a potentially serious problem. Your doctor can examine your nose, throat and sinuses and conduct testing to determine if antibiotics or other specific treatments are needed.
Conclusion
Post-nasal drip can result from viral colds and influenza, bacterial sinus infections, allergies, or irritants. Pay attention to your specific symptoms and see your doctor if they are severe, persist beyond 10 days, or are accompanied by warning signs like high fever or blood in mucus. With proper treatment, most cases of post-nasal drip can be effectively managed for your comfort and health.