"The Cough, Isn't it a Cold!?"—The True Nature of "Allergic Cough" that Persists Without Fever or Phlegm

1. What the Report from Brazil Taught Us

The UOL VivaBem article dated June 13 detailed cases where allergies are behind "persistent coughs without fever or phlegm." Otolaryngologist Cicero Matsuyama stated, "Coughing is originally a defensive reaction to expel foreign substances. The problem lies in a body that overreacts to allergens," pointing out that chemical detergents, paints in living environments, and mites lurking in old books and clothes are the main causesuol.com.br.

2. Voices of Sympathy Spreading on Japanese Social Media

After the article spread, posts with tags like <#PersistentCough> and <#AllergyCough> increased on X (formerly Twitter).

• Dr. Makoto Nagata from Saitama Medical University explained, "80% of coughs lasting more than three weeks are due to allergic mechanisms. If cough suppressants are ineffective, consider cough variant asthma or atopic cough," and recorded over 20,000 impressionstwitter.com.

• Harumachizaka Heart Clinic informed, "On days with high PM2.5, worsening of cough and asthma is noticeable"twitter.com.

• In Brazil, there are also numerous accounts like "At the UPA (emergency), they said it was 'just an allergy,' and I suffered for three months"twitter.com.

Replies to these posts include experiences of home care, such as "dramatic improvement with nasal irrigation" and "a futon dryer worked better than a Dyson," forming a community for information exchange.

3. What is Allergic Cough?

An allergic reaction stimulates the airway nerves, characterized by a dry and continuous cough. Unlike viral infections, there is no fever or fatigue, and it tends to worsen at night, early morning, or in dry airuol.com.br. The Japanese Respiratory Society recommends consulting a specialist if symptoms persist for four weeks or become chronic for more than eight weeks.

3-1 Five Steps Occurring in the Airway

1. Inhalation ─ Inhaling pollen, dust mites, pet dander, chemicals, etc.

2. IgE Antibodies Overreact

3. Histamine Release Causes Airway Mucosa Swelling

4. Postnasal Drip (Nasal Discharge Drips into Throat)

5. Airway Reflex Activates, Causing Repeated Coughing

4. Japan-Specific Environmental Factors

• Spring to Early Summer: Cedar and Cypress Pollen

• Autumn: Ragweed and Mugwort Pollen

• Yellow Sand & PM2.5: Peak Arrival from March to May

• High Humidity Rainy Season: Mold and Dust Mite Breeding Period
  Additionally, there are suggestions that the spread of remote work has increased exposure to "allergens lurking at home."

5. Three Pillars of Measures Recommended by Specialists

6. Over-the-Counter Medications and Self-Care Q&A

Q1: Do Over-the-Counter Cough Medicines Work?
A: Central antitussive drugs are less effective for allergic coughs. Syrups containing antihistamines or extracts of Hedera helix are considered to have some effect.uol.com.br.

Q2: Are Masks Effective?
A: They are essential not only for outdoor pollen and PM2.5 but also for house dust control during cleaning.N95 equivalent is ideal.

7. Checklist for Medical Consultation

• ✅ Cough persists for 4 weeks or worsens at night

• ✅ Wheezing sound or shortness of breath

• ✅ No improvement with over-the-counter medication

• ✅ Accompanied by other symptoms such as fever, weight loss, or bloody sputum

If any of these apply, consult a pulmonologist or allergist.

8. Summary

Assuming "persistent dry cough = cold" is dangerous. Reassess environmental factors and consider “cough as the body's SOS signal”, and partner with a specialist early. Combining the wisdom of everyday people from social media with medical knowledge should help you regain a cough-free, comfortable life.