Which red flag symptoms should prompt immediate further investigation in a patient with a chronic cough?

Red flag symptoms that should prompt immediate further investigation in a patient presenting with a chronic cough include:

• Age 40 years and over with unexplained haemoptysis (coughing up blood) — urgent chest X-ray and suspected cancer referral recommended ¹,⁴.
• Unexplained cough in people aged 40 and over who have ever smoked or have been exposed to asbestos, especially if accompanied by fatigue, shortness of breath, chest pain, weight loss, or appetite loss — urgent chest X-ray within 2 weeks is advised ¹,⁴.
• Persistent or recurrent chest infections in people aged 40 and over — consider urgent chest X-ray ¹.
• Chest signs consistent with lung cancer or pleural disease, or finger clubbing in people aged 40 and over — urgent chest X-ray recommended ¹,⁴.
• Severe clinical features indicating serious illness such as respiratory rate >30/min, tachycardia >130 bpm, systolic BP <90 mmHg, oxygen saturation <92% or central cyanosis, altered consciousness, use of accessory muscles of respiration, or signs of pulmonary embolism or pneumothorax — arrange emergency admission ².
• Persistent and unexplained hoarseness in people aged 45 and over — consider suspected cancer pathway referral ¹.

These red flags warrant urgent or immediate investigation to exclude serious underlying pathology including lung cancer, mesothelioma, or other life-threatening conditions ¹,²,⁴.