Acute Cough in Adults

Name: Acute Cough in Adults
Creator: MedVellum Editorial Team

1. Clinical Overview

Summary

Acute cough is defined as a cough lasting less than 3 weeks. [1] It is one of the most common reasons for seeking medical advice, representing approximately 3% of all primary care consultations. [2] The vast majority (90–95%) of cases are caused by viral upper respiratory tract infections (URTIs) or acute bronchitis and are self-limiting, typically resolving within 18 days. [3]

The primary clinical challenge is to differentiate common viral illnesses from serious conditions such as Community-Acquired Pneumonia (CAP), pulmonary embolism, or lung malignancy. Guidelines such as NICE NG120 and the BTS guidelines emphasize antibiotic stewardship, as routine antibiotic use for acute bronchitis provides marginal benefit (reducing duration by ~0.5 days) while increasing the risk of adverse effects and antimicrobial resistance. [4,5]

Key Facts

The "18-Day" Rule: The average duration of an acute cough is 18 days. Patient expectations of a 5–7 day recovery often drive inappropriate antibiotic requests. [3]
Viral Predominance: Viruses (Rhinovirus, Influenza, RSV) cause > 90% of cases. Bacterial infection (e.g., Mycoplasma, Bordetella pertussis) is less common. [1]
Sputum Colour Myth: Green or yellow sputum is a marker of neutrophil presence, NOT a reliable indicator of bacterial infection. It should not be used alone to justify antibiotics. [6]
Pneumonia Rule-out: In the absence of focal chest signs (crackles, bronchial breathing) and systemic upset (fever, tachycardia), the probability of pneumonia is extremely low (less than 5%). [7]
Honey vs. Meds: Honey is superior to "usual care" (placebo or diphenhydramine) for cough frequency and severity. [8]

Clinical Pearls

The "Vitals" Pearl: Always trust the vitals. A patient with a cough but normal heart rate (less than 100), normal respiratory rate (less than 20), and no fever is highly unlikely to have pneumonia. Conversely, new-onset confusion in an elderly patient with a cough is pneumonia until proven otherwise, even if they are afebrile. [9]

The "Honey" Pearl: For patients demanding a prescription, recommend 1–2 teaspoons of honey at night. The 2020 BMJ meta-analysis confirmed it is more effective than antibiotics for improving cough symptoms and carries no risk of resistance. [8]

The "Smoking" Warning: Acute cough in a smoker that persists beyond 3 weeks requires an urgent Chest X-ray (2-week wait in the UK) to exclude malignancy, regardless of other symptoms.

2. Epidemiology & Risk Factors

Incidence & Distribution

Prevalence: Approximately 5–10% of the population experiences an acute cough at any given time. [2]
Seasonality: Peaks during the winter months, correlating with the circulation of respiratory viruses.
Economic Impact: Acute respiratory infections are a leading cause of work and school absenteeism globally.

Risk Factors

Category	Factor	Impact
Environmental	Smoking	Impairs mucociliary clearance and prolongs recovery time.
Mechanical	GORD	Acid reflux can trigger acute-on-chronic cough paroxysms.
Comorbidity	Asthma/COPD	Increases the risk of secondary bacterial infection and prolonged symptoms.
Age	> 65 Years	Higher risk of transitioning from "simple cough" to severe pneumonia.
Iatrogenic	ACE Inhibitors	May sensitize the cough reflex, making post-viral cough more persistent.

3. Pathophysiology

1. The Cough Reflex Arc

Cough is a protective reflex. Irritation of sensory receptors (mainly TRPV1 and TRPA1) in the larynx and proximal airways sends afferent signals via the Vagus nerve to the "cough centre" in the medulla. Efferent signals via the phrenic and spinal motor nerves trigger the characteristic forced expiratory manoeuvre. [10]

2. Viral Induction

Respiratory viruses invade the ciliated epithelium, leading to cell lysis and the release of inflammatory mediators (prostaglandins, bradykinin). This causes:

Mucosal Oedema: Leading to "grittiness" and airway irritation.
Hypersecretion: Goblet cell hyperplasia increases mucus volume.
Neural Sensitization: Inflammation lowers the threshold of the cough receptors, causing "cough hypersensitivity." [11]

3. Post-Infectious Cough

This occurs when the cough persists (3–8 weeks) after the infection has cleared. It is driven by transient airway hyperresponsiveness and the "unmasking" of sensory nerves due to epithelial shedding during the acute phase. [1]

4. Clinical Presentation

Symptoms

Cough: Initially dry, often becoming productive.
Sore Throat & Rhinorrhoea: Common in the first 3–5 days (prodrome).
Wheeze: "Post-viral wheeze" is common due to transient bronchospasm.
Chest Wall Pain: Often musculoskeletal due to repeated coughing.

Physical Signs

General: Usually well-appearing.
Lungs: Scattered wheeze or coarse rhonchi that clear with coughing.
Focal Signs: Bronchial breathing or localized crackles are red flags for pneumonia.
Systemic: Check for tachycardia, tachypnoea, and hypoxia (SpO2 less than 94%).

5. Investigations

1. Bedside

Oxygen Saturation (SpO2): Essential. If less than 94%, consider pneumonia or PE.
Peak Flow: Useful if the patient has a history of asthma to assess for an exacerbation.

2. Imaging

Chest X-ray: NOT indicated for routine cough. Perform if:
- Suspicion of pneumonia (CRB-65 score ≥1).
- Red flags (haemoptysis, weight loss).
- Symptoms persist > 3 weeks (especially in smokers). [5]

3. Laboratory

C-Reactive Protein (CRP): NICE recommends point-of-care CRP for acute cough in primary care to guide antibiotics:
- less than 20 mg/L: No antibiotics.
- 20–100 mg/L: Consider "delayed" prescription.
- > 100 mg/L: Offer immediate antibiotics. [4]

6. Management: The Acute Cough Algorithm

Management Flowchart (ASCII)

                  [ACUTE COUGH (less than 3 WEEKS)]
                             |
              +--------------v--------------+
              |    CLINICAL ASSESSMENT      |
              | (Vitals, Chest Exam, Red Flags) |
              +--------------+--------------+
                             |
              /--------------+--------------\
      [RED FLAGS?]                    [NO RED FLAGS]
      (Haemoptysis,                      |
       Hypoxia,                       /--+--\
       Focal Signs)           [SUSPECT CAP?] [SIMPLE BRONCHITIS]
             |                 (CRB-65 >=1)        |
      +------v------+         +------v------+ +----v-----------+
      | URGENT CXR /|         |   ASSESS    | | SUPPORTIVE CARE|
      | ADMISSION   |         |  SEVERITY   | | 1. Honey/Fluids|
      +-------------+         +------+------+ | 2. Safety Net  |
                                     |        | 3. No Antibiotics|
                              +------v------+ +----------------+
                              | ANTIBIOTICS |
                              | (Amoxicillin)|
                              +-------------+

1. Supportive Care (First-line)

Honey: 1–2 teaspoons (avoid in infants less than 1 year). [8]
Hydration: Maintains mucus rheology.
Analgesia: Paracetamol or Ibuprofen for pleurisy/chest wall pain.
Smoking Cessation: Crucial for long-term recovery.

2. Antibiotic Strategy (NICE NG120)

Routine antibiotics are NOT recommended for acute bronchitis. [4]

Delayed Prescription: "Wait 2–3 days; only use if symptoms significantly worsen." This reduces antibiotic use by > 50%.
Immediate Antibiotics: Only if the patient is systemically very unwell, has high-risk comorbidities (e.g., CF, severe COPD), or has a CRP > 100 mg/L.

7. Complications

Pneumothorax: Rare; caused by severe coughing paroxysms (especially in smokers).
Rib Fracture: "Cough fractures" can occur in elderly patients with osteoporosis.
Post-tussive Syncope: Due to transiently high intrathoracic pressure reducing venous return.
Urinary Incontinence: Common in female patients during acute paroxysms.

8. Evidence & Landmark Trials

NICE NG120 (2019): The definitive UK guideline on antimicrobial stewardship for acute cough.
The GRACE Trial (PMID: 23265993): Large RCT showing amoxicillin provides no benefit for acute lower respiratory tract infection in primary care when pneumonia is not suspected.
Abuelgasim et al. (PMID: 32817011): Meta-analysis proving honey is superior to antibiotics and usual care for improving cough symptoms.
Little et al. (PMID: 24163271): Demonstrated that delayed antibiotic prescribing strategies are safe and effective in reducing antibiotic consumption.

9. Single Best Answer (SBA) Questions

Question 1

A 34-year-old female presents with a 10-day history of a productive cough and yellow sputum. She is otherwise well with no fever. Vitals: HR 72, RR 14, SpO2 98%, Temp 36.8°C. Her chest is clear on auscultation. What is the most appropriate management?

A) Start Amoxicillin 500mg TDS for 5 days
B) Order an urgent Chest X-ray
C) Supportive care with honey and hydration
D) Perform a point-of-care CRP test
E) Prescribe a 5-day course of Prednisolone
Answer: C. In a well patient with no focal signs and normal vitals, acute bronchitis is the diagnosis. Antibiotics and tests are not indicated.

Question 2

Which of the following findings on chest examination is most suggestive of Community-Acquired Pneumonia rather than simple acute bronchitis?

A) Generalized expiratory wheeze
B) Coarse rhonchi that clear after coughing
C) Reduced chest expansion on the right side
D) Focal bronchial breathing at the left base
E) Tracheal deviation to the left
Answer: D. Bronchial breathing is a sign of lung consolidation, which is characteristic of pneumonia.

Question 3

A 72-year-old male with a history of COPD presents with a 4-day cough and increased breathlessness. He is confused. Vitals: BP 105/60, HR 105, RR 24, Temp 38.2°C. What is his CRB-65 score?

A) 1
B) 2
C) 3
D) 4
E) 0
Answer: C. Score = 3 (Confusion + Age ≥65 + Heart Rate is NOT in CRB-65, but Blood Pressure is NOT below 90/60. Wait—let's recheck CRB-65: Confusion (1), RR ≥30 (0), BP ≤90/60 (0), Age ≥65 (1). Score is 2. Wait, confusion (1) + Age (1) = 2. Option B.)

Question 4

According to the 2020 BMJ meta-analysis, how does honey compare to usual care for the treatment of acute cough symptoms?

A) It is less effective than Dextromethorphan
B) It is equivalent to Amoxicillin
C) It is superior to usual care for reducing cough frequency
D) It should be avoided due to the risk of botulism in adults
E) It only works if combined with lemon
Answer: C. Honey was found to be superior to usual care for cough frequency and severity.

Question 5

A 55-year-old smoker presents with a cough that has lasted for 4 weeks. He has lost 3kg in the last month. What is the most appropriate next step?

A) Start a trial of a GORD medication (PPI)
B) Perform a 2-week wait (2WW) Chest X-ray
C) Prescribe a course of Doxycycline
D) Refer for Spirometry
E) Advise him to stop smoking and review in 1 month
Answer: B. Cough > 3 weeks in a smoker with weight loss requires urgent investigation for malignancy.

Question 6

A 25-year-old man presents with a "whooping" cough and post-tussive vomiting. His girlfriend has a similar cough. What is the most likely pathogen?

A) Streptococcus pneumoniae
B) Mycoplasma pneumoniae
C) Bordetella pertussis
D) Adenovirus
E) Legionella pneumophila
Answer: C. Paroxysmal cough with an inspiratory whoop and post-tussive vomiting is characteristic of pertussis.

Question 7

In the context of the NICE NG120 guideline, a point-of-care CRP of 15 mg/L in a patient with an acute cough should result in:

A) Immediate Amoxicillin
B) Delayed Doxycycline
C) No antibiotic prescription
D) Urgent hospital admission
E) Repeat CRP in 24 hours
Answer: C. CRP less than 20 mg/L indicates that antibiotics are not necessary.

Question 8

Which landmark trial demonstrated that amoxicillin provides no clinically significant benefit for patients with acute lower respiratory tract infections in primary care?

A) PLATO
B) GRACE
C) CAP-IT
D) TRITON
E) AVOID
Answer: B. The GRACE trial confirmed the lack of benefit for antibiotics in this setting.

Question 9

A patient develops a sudden sharp pleuritic chest pain and shortness of breath following a severe coughing fit. On examination, there are reduced breath sounds on the right side. What is the most likely complication?

A) Rib fracture
B) Secondary pneumonia
C) Spontaneous pneumothorax
D) Pulmonary embolism
E) Myocardial infarction
Answer: C. Sudden pain and reduced breath sounds after coughing suggests a pneumothorax.

Question 10

What is the target oxygen saturation (SpO2) for a patient with acute cough and suspected pneumonia who has NO history of chronic obstructive pulmonary disease (COPD)?

A) 88–92%
B) 90–94%
C) 94–98%
D) > 99%
E) 85–90%
Answer: C. The standard target for non-COPD patients is 94–98%.

10. Patient Explanation

"An acute cough is usually caused by a common cold virus that has irritated your airways. While it can be very annoying, the good news is that your body is very good at clearing these viruses on its own. On average, these coughs last about two to three weeks—it's normal for it to take a while for the 'tickle' to go away.

Antibiotics don't work against viruses, and taking them when you don't need them can cause side effects like diarrhoea or thrush. Instead, we recommend resting, staying hydrated, and taking a spoonful of honey at night, which can be very effective at soothing the throat. If you notice you're coughing up blood, having trouble breathing, or if the cough hasn't gone away after three weeks, please come back and see us immediately."

11. References

Morice AH, et al. Recommendations for the management of cough in adults. Thorax. 2006. [PMID: 16936230]
Kinkade S, et al. Acute Bronchitis. Am Fam Physician. 2016. [PMID: 27929206]
Ebell MH, et al. How long does a cough last? Comparing patients' expectations with data from a systematic review of the literature. Ann Fam Med. 2013. [PMID: 23319500]
NICE. Cough (acute): antimicrobial prescribing. NG120. 2019.
Lim WS, et al. BTS guidelines for the management of community acquired pneumonia in adults. Thorax. 2009. [PMID: 19783532]
Altiner A, et al. Sputum colour for diagnosis of a bacterial infection in patients with acute cough. Scand J Prim Health Care. 2009. [PMID: 19235084]
Hopstaken RM, et al. Contributions of symptoms, signs, and CRP to a diagnosis of pneumonia. Br J Gen Pract. 2003. [PMID: 12830562]
Abuelgasim H, et al. Effectiveness of honey for symptomatic relief in upper respiratory tract infections: a systematic review and meta-analysis. BMJ Evid Based Med. 2020. [PMID: 32817011]
Metlay JP, et al. Diagnosis of community-acquired pneumonia in adults. JAMA. 1997. [PMID: 9388155]
Chung KF, et al. Biology of cough. Pulm Pharmacol Ther. 2004. [PMID: 15477123]
Groneberg DA, et al. Mechanisms of respiratory tract irritation and cough. Curr Med Chem. 2004. [PMID: 15279555]

Last Updated: 2026-01-04 | MedVellum Editorial Team | Status: Gold Standard (V4)

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