Sudden Hearing Loss: Why It Is a Medical Emergency and What to Do Immediately
- Vyas Prasad
- May 24
- 7 min read
Updated: 4 days ago
Sudden sensorineural hearing loss — a rapid drop in hearing within 72 hours — is a medical emergency
It originates in the inner ear, not from earwax or congestion
High-dose corticosteroids within 24–48 hours of onset give the best chance of recovery
Same-day specialist assessment is essential — delays reduce the likelihood of recovery
Sudden sensorineural hearing loss — a rapid, significant reduction in hearing in one ear occurring within 72 hours — is a medical emergency requiring same-day assessment and treatment. High-dose corticosteroids started within the first 24 to 48 hours of onset give the best chance of meaningful recovery; delays of even a few days significantly worsen outcomes.
Sudden sensorineural hearing loss — a rapid, unexplained deterioration in hearing in one ear — is one of the few genuine ENT emergencies. Unlike many conditions where a wait-and-see approach is reasonable, sudden hearing loss requires same-day assessment and treatment. The evidence is clear: the sooner treatment begins, the better the chance of meaningful recovery. Delays of even a few days significantly worsen outcomes.
This article explains what sudden hearing loss is, what causes it, why it demands urgent attention, and what treatment involves.
What Is Sudden Sensorineural Hearing Loss?
Sudden sensorineural hearing loss (SSNHL) is defined as a loss of 30 decibels or more across three consecutive frequencies on a hearing test, occurring within 72 hours. In practice, most patients notice a dramatic and obvious reduction in hearing — often upon waking — in one ear, sometimes accompanied by a sensation of fullness, tinnitus, or dizziness.
The word sensorineural distinguishes this from conductive hearing loss — which is caused by problems in the outer or middle ear such as earwax, a perforated eardrum, or fluid. Sensorineural hearing loss originates in the inner ear (cochlea) or the auditory nerve, and is a fundamentally different and more serious problem.
SSNHL occurs in approximately 5 to 20 cases per 100,000 people per year. It is most commonly unilateral — affecting one ear only — and in the majority of cases no definitive cause is identified (idiopathic SSNHL). However, several important causes must be excluded through investigation.
What Does Sudden Hearing Loss Feel Like?
Patients typically describe:
A sudden muffling or blockage of hearing in one ear — often noticed immediately upon waking
A sensation that the affected ear is "stuffed" or underwater
Tinnitus — ringing, buzzing, or hissing in the affected ear
A feeling of fullness or pressure in the ear
Occasionally, dizziness or vertigo
The onset may be instantaneous — like a switch being turned off — or may progress over hours. Some patients first notice it when trying to use the phone on the affected side, or when covering their good ear.
Why Is Sudden Hearing Loss an Emergency?
The cochlea is exquisitely sensitive to disruption of its blood supply and metabolic environment. Whatever the cause of sudden hearing loss — whether vascular, viral, inflammatory, or auto-immune — the window for effective treatment is narrow.
High-dose corticosteroids are the primary treatment for SSNHL and work by reducing cochlear inflammation and oedema. Studies consistently show that outcomes are significantly better when steroids are started within the first few days of onset. Treatment started beyond two weeks from onset is much less likely to result in recovery.
This is why sudden hearing loss should not be managed with a "wait and see" approach, or treated initially as earwax or Eustachian tube dysfunction without proper assessment. Any sudden reduction in hearing in one ear that is not immediately explained by an obvious cause such as earwax should be assessed as an emergency.
Causes of Sudden Hearing Loss
Idiopathic (Unknown Cause)
The majority — around 85 to 90% — of cases of SSNHL have no identifiable cause despite thorough investigation. This is termed idiopathic SSNHL. The leading hypothesis is that most idiopathic cases are caused by viral infection of the cochlea or auditory nerve, or by vascular disruption — but in most cases it is impossible to confirm this.
Viral Infection
Viral labyrinthitis — inflammation of the inner ear caused by viral infection — is one of the most commonly implicated causes. Viruses associated with SSNHL include herpes simplex, herpes zoster, cytomegalovirus, mumps, and measles. A preceding or concurrent viral illness is a common finding in patients with SSNHL.
Vascular Causes
The cochlea is supplied by the labyrinthine artery — a small end-artery with no collateral circulation. Disruption of blood flow to this vessel can cause sudden cochlear infarction. Vascular SSNHL is more likely in older patients with cardiovascular risk factors.
Acoustic Neuroma (Vestibular Schwannoma)
An acoustic neuroma — a benign tumour arising from the vestibulocochlear nerve — can present with sudden hearing loss in a small but important minority of cases. This is why MRI imaging is an important part of the investigation of SSNHL. The hearing loss associated with acoustic neuroma may be sudden or gradually progressive, and is typically accompanied by unilateral tinnitus.
Autoimmune Inner Ear Disease
In some patients — particularly those with a known autoimmune condition — the immune system attacks the inner ear, causing rapid bilateral or rapidly progressive hearing loss. This is an important diagnosis to consider as it may respond to immunosuppressive treatment.
Ménière's Disease
Ménière's disease can cause sudden drops in hearing as part of its characteristic episode of vertigo, hearing loss, tinnitus, and ear fullness. Repeated episodes of fluctuating hearing loss are characteristic.
Perilymphatic Fistula
A tear in the membranes separating the middle and inner ear, sometimes following barotrauma (straining, diving, or heavy lifting), can cause sudden hearing loss. This is a less common but important cause to consider in the right clinical context.
Other Causes
Less commonly, sudden hearing loss may result from multiple sclerosis, stroke affecting the auditory pathways, syphilis, or certain medications (ototoxic drugs including some chemotherapy agents, aminoglycoside antibiotics, and loop diuretics in high doses).
Assessment of Sudden Hearing Loss
History
A detailed history establishes the timeline of onset, any preceding illness, noise exposure, barotrauma, medication use, and associated symptoms — particularly tinnitus, vertigo, and ear fullness. A history of autoimmune disease, cardiovascular risk factors, or previous ear conditions is relevant.
Examination
Otoscopy to examine the ear canal and eardrum — to exclude simple mechanical causes such as earwax or a perforated eardrum. Tuning fork tests (Rinne and Weber) to characterise the nature of the hearing loss.
Audiometry
Formal pure tone audiometry is essential to document the degree and pattern of hearing loss and provide a baseline against which recovery can be measured. This should be performed urgently — on the same day or the following day where possible.
Blood Tests
Depending on the clinical picture, blood tests may include full blood count, inflammatory markers, syphilis serology, autoimmune screen, and thyroid function.
MRI Imaging
MRI of the internal auditory canals with gadolinium contrast is recommended in all patients with SSNHL to exclude an acoustic neuroma. This does not need to be performed on the day of presentation but should be arranged within the following weeks.
Treatment of Sudden Hearing Loss
Systemic Corticosteroids
High-dose oral prednisolone is the primary treatment for SSNHL. A typical regimen is prednisolone 1mg/kg/day (up to 60mg) for one to two weeks, followed by a taper. Treatment should begin as soon as possible after diagnosis — within 24 to 48 hours of onset where feasible.
Patients with diabetes or other contraindications to systemic steroids require careful consideration of the risk-benefit balance.
Intratympanic Steroid Injections
Steroid can be injected directly through the eardrum into the middle ear, where it diffuses into the inner ear. Intratympanic steroid injection (IT-steroid) is used:
As primary treatment in patients who cannot take systemic steroids
As salvage treatment in patients who have not responded to systemic steroids
In combination with systemic steroids in some protocols
The injection is performed in clinic under local anaesthetic and is well tolerated by most patients.
Other Treatments
Hyperbaric oxygen therapy has some evidence supporting its use in SSNHL, particularly as an adjunct to steroids or as salvage therapy for patients who have not recovered with steroid treatment. Access to hyperbaric facilities is limited but it is worth discussing where available.
Antiviral medication (aciclovir or valaciclovir) is sometimes prescribed alongside steroids where a viral aetiology is suspected, though the evidence for antivirals alone is less robust than for steroids.
Bed rest, reduced stress, and avoidance of loud noise during the recovery period are generally advised.
Prognosis
The prognosis of SSNHL is variable and depends on several factors:
Favourable prognostic factors:
Mild to moderate hearing loss (rather than profound loss)
Low-frequency hearing loss pattern
Absence of vertigo
Early treatment
Younger age
Unfavourable prognostic factors:
Profound hearing loss at presentation
High-frequency hearing loss pattern
Presence of significant vertigo
Delayed treatment
Older age and cardiovascular comorbidities
Overall, approximately one-third of patients recover fully, one-third recover partially, and one-third have little or no meaningful recovery. These figures reinforce the importance of early treatment — even partial recovery is a meaningful outcome that makes a significant difference to quality of life.
What If Hearing Does Not Recover?
For patients with significant permanent unilateral hearing loss, rehabilitation options include:
CROS or BiCROS hearing aids — devices that pick up sound from the deaf ear and transmit it to the hearing ear, improving awareness of sound from the affected side.
Bone-anchored hearing aids (BAHA) — a surgically implanted device that conducts sound through bone directly to the hearing cochlea.
Cochlear implantation — in selected patients with severe to profound unilateral hearing loss who are not adequately helped by conventional amplification, cochlear implantation may be considered.
Frequently Asked Questions
I woke up this morning with muffled hearing in one ear. What should I do?
Seek assessment today. Do not wait to see if it improves. Contact your GP or ENT clinic urgently, or attend an emergency department if same-day ENT assessment is not available. Early treatment significantly improves the chance of recovery.
Could it just be earwax?
Earwax can cause a muffled sensation, particularly if it becomes compacted after water exposure. However, earwax should not be assumed to be the cause without examination. If earwax is found and removed but hearing does not immediately improve, SSNHL should be considered.
Can sudden hearing loss happen in both ears?
Bilateral sudden hearing loss is much less common than unilateral and raises greater concern for systemic causes — autoimmune disease, bilateral acoustic neuromas (associated with neurofibromatosis type 2), or vascular causes. It requires urgent investigation.
Will I need a hearing aid permanently?
This depends on the degree of recovery. Many patients recover sufficient hearing that amplification is not needed. Those with significant permanent loss are assessed for the most appropriate rehabilitation strategy.
Is sudden hearing loss related to stress?
There is some evidence that psychological stress may be a risk factor for SSNHL, possibly through its effects on immune function and the vascular supply to the inner ear. However, stress alone does not cause sudden hearing loss in most people, and many patients have no identifiable stress-related precipitant.
Book an Urgent Assessment
Sudden hearing loss is a medical emergency. If you are experiencing it now, contact Dr Vyas Prasad immediately — same-day assessment is available.
Dr Vyas Prasad consults at Camden Medical Centre, 1 Orchard Boulevard, #09-08, Singapore. WhatsApp: +65 8060 8079. Email: camden.mmc@gmail.com.
Great advice