• Oedema
• Anaphylaxis (Chapter 38)
• Angioedema – angiotensin-converting enzyme inhibitors, C1 inhibitor deficiency (Chapter 27)
• Post-extubation laryngeal oedema – typically a few hours after extubation

Extrinsic compression

• Thyroid masses – benign or malignant
• Lymphadenopathy of any cause
• Neck haematoma, for example arterial puncture complicating central venous access

Tumours of the airway

• Laryngeal carcinoma
• Tracheal carcinoma

Infection

• Retropharyngeal abscess
• Ludwig's angina
• Laryngitis and epiglottitis

Vocal cord paralysis

• Recurrent laryngeal nerve palsy of any cause
• Cricoarytenoid disease in rheumatoid arthritis

Trauma

• Acute laryngeal trauma
• Facial fractures and associated haemorrhage
• Thermal inhalation injury to mucosa
• Tracheal stenosis following intubation or tracheostomy

Foreign bodies