Several viruses can cause hearing loss in adults, but the most common culprits are varicella zoster (the shingles virus), cytomegalovirus, mumps, HIV, and SARS-CoV-2. Viral infections are one of the leading suspected causes of sudden hearing loss, though pinpointing the exact virus responsible in a given case is often difficult. Most sudden hearing loss cases are classified as idiopathic, meaning no definitive cause is identified, but viral infection of the inner ear remains one of the top theories.
How Viruses Damage Your Hearing
Your inner ear contains tiny sensory cells called hair cells that convert sound vibrations into electrical signals for the brain. These cells are fragile and do not regenerate once destroyed. When a virus infects the inner ear, it doesn’t always attack hair cells directly. Instead, research shows that the virus often infects the supporting cells surrounding the hair cells. Those infected supporting cells then produce a signaling molecule that triggers the hair cells to die through a process called necroptosis, a form of inflammatory cell death.
Hair cells carry specific receptors for this death signal on their surface, while the surrounding support cells mostly do not. This explains why viral infections can wipe out the sensory cells responsible for hearing while leaving nearby tissue relatively intact. Corticosteroids, the primary treatment for sudden hearing loss, appear to work in part by preventing these infected support cells from transforming into immune-like cells that amplify the damage.
Viruses can also harm the blood supply to the inner ear, damage the nerve that carries sound signals to the brain, or trigger an inflammatory immune response that causes collateral destruction. The specific pattern depends on the virus involved.
Varicella Zoster and Ramsay Hunt Syndrome
The varicella zoster virus, which causes chickenpox in childhood and shingles in adults, is one of the most clearly documented viral causes of hearing loss. After a childhood chickenpox infection, the virus lies dormant in nerve clusters near the brain. When it reactivates, it can travel along the facial nerve and affect the nearby hearing and balance nerve due to their close proximity inside the skull.
This reactivation is called Ramsay Hunt syndrome. It typically causes a painful rash on or around the ear, facial paralysis on one side, and hearing problems. In one large case series, 43% of patients with Ramsay Hunt syndrome had sensorineural hearing loss, 51% experienced vertigo or imbalance, and 20% had tinnitus. The hearing loss occurs because the virus causes severe inflammation and swelling of the nerve inside a narrow bony canal in the skull, physically compressing and injuring the nerve fibers.
Ramsay Hunt syndrome is more common in older adults and people with weakened immune systems. The hearing loss can range from mild to profound and is not always reversible.
COVID-19 and Hearing Loss
SARS-CoV-2 has emerged as a significant concern for hearing health. A large study using insurance claims data found that people who had COVID-19 developed hearing loss at roughly 3.5 times the rate of uninfected individuals (11.9 versus 3.4 cases per 10,000 person-months). The risk of sudden hearing loss specifically was also about 3.5 times higher in the COVID group.
Young adults appeared particularly vulnerable, especially those with diabetes or abnormal cholesterol levels. Among young adults with diabetes who had COVID, the risk of hearing loss was more than four times higher than in uninfected peers. The exact biological mechanism is still being studied, but the virus’s known ability to cause inflammation in blood vessels and nerve tissue likely plays a role, since the inner ear depends on a delicate blood supply.
HIV and Hearing Damage
HIV affects hearing through multiple pathways, making it one of the more complex viral causes. The virus itself is neurotropic, meaning it targets nerve tissue, and researchers have identified viral particles directly inside structures of the inner ear in HIV-positive patients with hearing loss. These particles were found in the membrane that sits on top of the hair cells, along with visible damage to the inner ear lining.
Beyond the virus itself, people living with HIV face hearing threats from opportunistic infections like cytomegalovirus, tuberculosis, and fungal infections that can damage the ear. Some of the medications used to treat both HIV and these secondary infections carry their own risk of hearing damage. Studies of HIV-positive individuals consistently find high-frequency hearing loss, the type that affects the ability to understand speech clearly, especially in noisy environments. The hearing loss in HIV is generally considered multifactorial: a combination of the virus, secondary infections, and medication side effects.
Mumps in Adults
Mumps is often thought of as a childhood disease, but adults who were never vaccinated or whose immunity has waned can still contract it. Mumps-related hearing loss is almost always sudden, usually affects one ear, and is typically permanent. A nationwide survey in Japan from 2015 to 2016 identified 348 confirmed cases of mumps-related deafness, 16 of which were bilateral (affecting both ears). Unilateral hearing loss from mumps can range from moderate to complete deafness in the affected ear, and there is currently no effective treatment to reverse it.
Other Viruses Linked to Hearing Loss
Cytomegalovirus (CMV) is best known for causing hearing loss in newborns, but it can also affect adults with compromised immune systems, such as organ transplant recipients or people undergoing chemotherapy. In these individuals, CMV can reactivate and damage the inner ear.
Measles, though rare in vaccinated populations, can cause hearing loss through direct inner ear damage or secondary ear infections. Herpes simplex virus types 1 and 2 have also been implicated in sudden hearing loss, though proving a direct causal link is difficult because these viruses are so common in the general population.
Sudden Hearing Loss and the Treatment Window
Viral hearing loss in adults most often presents as sudden sensorineural hearing loss: a rapid decline in hearing, usually in one ear, that develops over hours to a few days. You might notice muffled hearing when you wake up, a popping sensation, or new ringing in the ear. Some people also experience dizziness or a sense of fullness in the ear.
This is a medical urgency. High-dose oral steroids are the standard treatment and work best when started as soon as possible, ideally within the first two weeks of symptom onset. Treatment can be attempted up to six weeks after onset, but the chances of meaningful recovery drop significantly after that window. Beyond six weeks, there is little chance of success with steroid therapy. Recovery depends heavily on how severe the initial hearing loss is.
Diagnosing the specific viral cause is often impossible in practice. Blood tests can sometimes detect recent infections, and MRI can reveal nerve inflammation, but in most cases of sudden hearing loss, no definitive cause is found. Treatment with steroids proceeds regardless of whether a specific virus is identified, because the goal is to reduce inner ear inflammation before permanent damage sets in.
Who Is Most at Risk
Your risk of virus-related hearing loss increases with age, since immune function naturally declines over time. People with diabetes, high cholesterol, or any condition that affects blood vessel health face higher risk because the inner ear’s blood supply is already more vulnerable. Immunocompromised individuals, whether from HIV, cancer treatment, organ transplantation, or autoimmune medications, are at particular risk because latent viruses like CMV and varicella zoster are more likely to reactivate when immune surveillance drops.
Vaccination remains the most effective prevention for the viruses where vaccines exist. The shingles vaccine significantly reduces the risk of varicella zoster reactivation and Ramsay Hunt syndrome. MMR vaccination prevents mumps-related deafness. For viruses without vaccines, prompt attention to any sudden change in hearing gives you the best chance of preserving it.