The most common cause of laryngitis is an infection with one of the viruses that cause upper respiratory tract infections. Less commonly, it may be caused by bacterial infection, or may be a symptom of another infection (e.g. measles, mumps or chicken pox), or an autoimmune disease (e.g. rheumatoid arthritis).
Other causes may include irritation of the larynx due to:
- Over-using the voice (e.g. singing or yelling loudly or for long periods)
- Cigarette smoke or other inhaled toxins (e.g. air pollution)
- Use of asthma inhalers
- Gastric acids in reflux disease.
The loss of voice occurs because when the voice box becomes inflamed, the vocal chords are unable to vibrate as they usually do, and consequently are incapable of producing sound, or can only produce limited sounds.