Bacterial infections are another cause of acute laryngitis, and sometimes they can develop during or right after a viral infection - that's called a superinfection.
For chronic laryngitis, it's important to treat the underlying issue, for example, using allergy medication, avoiding irritating agents, and using gastroesophageal reflux medications.
In chronic laryngitis the normal columnar cells undergo dysplasia, which is when they transform into squamous epithelium to adapt to the chronic irritation.
Finally, there's overuse of the voice, like yelling or a really prolonged karaoke session involving the Beatles, that could lead to both acute and chronic laryngitis.
Another complication is when the reflux goes all the way back up to the pharynx, and then into the larynx, in which case it can cause laryngitis or even asthma.
In acute laryngitis, the goblet cells to over secrete mucus leading to congestion of the airway, and immune cells like neutrophils and macrophages release chemicals that cause pain and swelling.
Reflux laryngitis is another cause of chronic laryngitis and develops in people with severe gastroesophageal reflux disease where acid from the stomach goes all the way up the esophagus into the pharynx.