Tinnitus, or ringing in the ear, is the perception of sound that has no objective source external to the patient's body. It is a common disorder affecting 10%-25% of people. It is often described as a humming, hissing, static, or roaring sound, which can be present bilaterally or unilaterally.

There are two broad categories of tinnitus: objective and subjective. Objective tinnitus comes from a source within the body that can technically be perceived by someone other than the patient. Subjective tinnitus, the more common of the two, can only be perceived by the patient. Tinnitus can also be distinguished via pulsatile or nonpulsatile symptoms. Although many people with tinnitus acclimate to the perceived sound over time, it severely impacts quality of life in 1%-7% of the population.

Risk factors for tinnitus include hearing loss, older age, and male sex. Those with occupational noise exposure are at a greater risk. Although the prevalence is higher in older populations, the condition can occur in younger patients. Studies have demonstrated that tinnitus is more common in those with hearing loss and can similarly resolve with hearing restoration. Of note, the disease process is highly variable and can worsen, improve, or even resolve entirely with time.

Limited reports of tinnitus have been documented in association with Pfizer-BioNTech, Moderna, and AstraZeneca shots, as well as COVID-19. These reports suffer from a number of limitations including recall bias, nocebo effect, and survey methodology. Causality has not been determined and studies that include control groups, audiometric data, and more accurate patient reporting are needed. A plausible mechanism of action involving the vestibulocochlear nerve has been suggested if causality is ultimately proven.