What Virus Causes Sudden Hearing Loss

Sudden hearing loss is frightening precisely because it arrives without obvious explanation. One morning everything sounds normal. By evening, one ear feels muffled, distant, or completely silent. No injury. No loud noise. No clear trigger. And yet something has changed, quickly and significantly, in the way the auditory system is functioning.

For a meaningful proportion of people who experience this, the answer lies not in the ear itself but in something the body has recently been fighting: a viral infection. Understanding what virus causes sudden hearing loss is not just medically interesting. It is clinically important, because identifying the cause shapes the treatment approach and the realistic expectation of recovery.

How Viruses Damage the Inner Ear

The inner ear is a remarkable and delicate structure. The cochlea, responsible for converting sound vibrations into electrical signals the brain interprets as hearing, contains thousands of microscopic hair cells that do not regenerate once damaged. The auditory nerve, which carries those signals to the brain, is similarly vulnerable.

Viruses can reach the inner ear through several routes. Some travel through the bloodstream and cross into the cochlear fluid directly. Others migrate along nerve pathways, reaching the auditory nerve or the structures surrounding it without ever entering the bloodstream in significant quantities. Once inside, they trigger an inflammatory response that damages hair cells, disrupts cochlear blood flow, or causes swelling along the auditory nerve itself.

The result can be a sudden, significant drop in hearing, often accompanied by tinnitus, a sensation of fullness in the ear, and occasionally dizziness if the vestibular system is also affected.

The Viruses Most Commonly Implicated

When asking what virus causes sudden hearing loss, the honest answer is that several have been identified, each operating through slightly different mechanisms:

Herpes Simplex Virus (HSV): Both HSV-1 and HSV-2 have been associated with sudden sensorineural hearing loss. The virus can remain dormant in nerve tissue for years and reactivate under conditions of stress or immune suppression, migrating along the auditory nerve and triggering inflammatory damage. It is among the most frequently cited viral causes in peer-reviewed literature.

Varicella Zoster Virus: The same virus responsible for chickenpox and, in its reactivated form, shingles. When shingles affects the facial nerve and ear, a condition known as Ramsay Hunt syndrome, it can cause sudden hearing loss alongside facial paralysis, ear pain, and a characteristic rash around the ear canal. This is one of the more clinically recognisable viral presentations.

Mumps: Before widespread vaccination, mumps was one of the leading identifiable causes of sudden unilateral hearing loss, particularly in children. The virus has a well-documented affinity for the cochlea and can cause rapid, severe, and often permanent hearing loss in the affected ear.

Cytomegalovirus (CMV): Particularly significant in congenital hearing loss when passed from mother to child during pregnancy, CMV is also associated with acquired sudden hearing loss in immunocompromised adults. It is one of the most common cause of hearing loss in newborns globally.

Epstein-Barr Virus: The virus behind infectious mononucleosis has been implicated in sudden hearing loss, though the mechanism is less clearly defined than in herpes-family viruses. Cases are documented but considered less frequent than HSV-related presentations.

COVID-19: Since 2020, an accumulating body of research has investigated links between SARS-CoV-2 infection and sudden auditory changes. The proposed mechanisms include microangiopathy affecting cochlear blood supply, systemic inflammation, and direct viral involvement in the inner ear. Evidence continues to develop, and the relationship is taken seriously by audiologists and ENT specialists internationally.

Hearing Loss Due to Cold and Upper Respiratory Infections

A question that comes up frequently in clinical practice is whether a common cold can cause genuine hearing loss. Hearing loss due to cold is real, though it typically involves a different mechanism than direct viral cochlear damage.

Upper respiratory infections cause congestion and inflammation that can block the Eustachian tube, the channel connecting the middle ear to the back of the throat. When this tube becomes blocked, fluid accumulates in the middle ear, creating a conductive hearing loss that is usually temporary and resolves as the infection clears.

However, hearing loss due to cold can occasionally involve the inner ear if the viral infection spreads beyond the upper respiratory tract. This is less common but more serious, and it is why sudden or significant hearing change during or shortly after a respiratory illness should always be evaluated rather than assumed to be purely congestion-related.

Jaw and Throat Pain as a Warning Sign

One symptom combination that is worth taking seriously is the simultaneous presence of ear-related symptoms alongside jaw and throat pain. This pairing can indicate several conditions relevant to hearing health.

Ramsay Hunt syndrome, mentioned earlier, often presents with deep ear pain that radiates toward the jaw and throat before the characteristic rash appears. Recognising jaw and throat pain alongside sudden hearing change as a potential sign of viral nerve involvement means faster diagnosis and faster access to antiviral treatment, which is most effective when started early.

Temporomandibular joint dysfunction, while not viral in origin, can also produce a combination of jaw pain and ear symptoms including tinnitus and a sensation of blocked or reduced hearing. The anatomical proximity of the jaw joint to the ear canal means that inflammation in one area frequently affects perception in the other.

The Most Common Cause of Hearing Loss Overall

It is worth placing viral sudden hearing loss in its broader context. While viruses represent a significant and important subset of cases, they are not the most common cause of hearing loss across the population as a whole.

Age-related hearing loss, known as presbycusis, holds that position by a considerable margin, affecting a significant proportion of adults over sixty and the majority of those over seventy-five. Noise-induced hearing loss, accumulating over years of occupational or recreational sound exposure, sits alongside it as a leading preventable cause. Genetic factors account for a substantial proportion of hearing loss present from birth or developing in early life.

Viral causes are particularly significant because they tend to produce sudden, dramatic, and often unilateral hearing change in people who had no prior hearing difficulty, making them disproportionately alarming even if they are not the numerically dominant cause across the whole population.

Why Acting Quickly Matters

Regardless of which virus is responsible, the treatment window for sudden sensorineural hearing loss is narrow. High-dose oral corticosteroids, started within 72 hours of onset, offer the best chance of partial or full recovery by reducing inflammation before permanent hair cell damage becomes established. Antiviral medications are added when a specific viral cause such as herpes zoster is identified or strongly suspected.

Waiting to see whether hearing returns on its own is the most common and most costly mistake people make. Every day of delay narrows the recovery window. If hearing changes suddenly and significantly in one ear, that is a same-day medical situation, not a wait-and-see one.

At Zenaud, we take sudden hearing change seriously as the clinical emergency it is. Our team is equipped to assess, investigate, and refer rapidly when time-sensitive intervention is needed.

Experiencing sudden hearing change? Do not wait. Contact Zenaud today for an urgent hearing assessment.

FAQs

Why have I gone deaf in one ear overnight?
Sudden deafness in one ear may be due to sudden sensorineural hearing loss, infection, or blockage.

Is there a virus that can cause hearing loss?
Yes, viral infections like mumps, measles, and COVID-19 can cause hearing loss.

What is sudden hearing loss called?
Sudden hearing loss is called sudden sensorineural hearing loss (SSNHL).

Can hearing loss come back?
Some types of hearing loss can improve or return with treatment, especially if treated early.