<s>[INST] Causes of an Ear Infection [/INST] 
Ear infections occur when the eustachian tubes, which connect your middle ear to your upper throat, become inflamed or blocked. This infection causes fluid to build up in the middle ear. 

Illnesses such as colds and the flu can cause ear infections. Allergies are also a common cause. Sinus infections and an abundance of mucus can cause the eustachian tubes to swell. Ear infections happen whenever your health is compromised and a virus or bacterium finds a way into your middle ear.  Source: BASS MEDICAL GROUP . Link: https://www.bassmedicalgroup.com/blog-post/ear-infection-how-long-does-it-last-when-should-you-see-a-doctor. Field: Otolaryngology. Disease: Ear Infection </s>