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Health condition · Clinically reviewed

Deafness in one ear, the causes that matter, the scan you need and the rehab that works.

Sudden or gradual, unilateral hearing loss deserves a proper answer. A time-critical steroid window for SSNHL, an MRI to rule out acoustic neuroma, and modern devices that restore useful hearing.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BAOHNS and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including MRI IAM protocols, high-dose steroids for SSNHL and CROS, BAHA and cochlear implant rehabilitation.

Key facts

Deafness in one ear at a glance.

The essentials, in plain English - what it is, the emergency pattern, and how it is worked up in the UK today.

  • What it is

    Hearing loss in one ear with normal or near-normal hearing in the other, ranging from mild asymmetry to single-sided deafness (SSD).

  • Sudden vs gradual

    Sudden sensorineural hearing loss (SSNHL) is an emergency. Gradual loss usually points to slow-growing causes such as acoustic neuroma.

  • The emergency pattern

    A drop of 30 dB or more across three contiguous frequencies within 72 hours needs urgent ENT within 2 weeks - steroids are time-critical.

  • The scan that matters

    MRI of the internal auditory meati with gadolinium is the gold standard for any unexplained asymmetric sensorineural hearing loss.

  • Rehabilitation works

    CROS/BiCROS aids, bone-anchored hearing aids and cochlear implants can restore useful hearing and spatial awareness in SSD.

  • It is not just hearing

    Unilateral loss affects speech in noise, localisation, fatigue and confidence - a full plan addresses all of it.

Why this guide matters

Three things that shape a good outcome.

Unilateral hearing loss is common, and the way it is worked up in the first few weeks decides much of what follows.

  • SSNHL is time-critical

    A sudden drop in hearing is an emergency. Steroids given within 2 weeks give the best chance of recovery - do not wait for a routine appointment.

  • MRI IAM is non-negotiable

    Any asymmetric sensorineural hearing loss deserves an MRI of the internal auditory meati to rule out acoustic neuroma and other CPA lesions.

  • Rehabilitation restores function

    CROS aids, bone-anchored hearing aids and cochlear implants have transformed what is possible for single-sided deafness.

How the diagnosis is made

From first noticing to a clear plan.

The steps a UK GP, audiologist or ENT surgeon will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and onset

    Sudden or gradual, tinnitus, vertigo, aural fullness, discharge, noise exposure, trauma, ototoxic drugs and family history.

  2. 02

    Assessing

    Otoscopy and tuning forks

    Wax, tympanic membrane, effusion or perforation. Rinne and Weber (256 Hz and 512 Hz) separate conductive from sensorineural loss.

  3. 03

    Assessing

    Cranial nerve exam

    Facial nerve, balance and neurological screen - important for CPA lesions and Ramsay Hunt.

  4. 04

    Confirming

    Pure tone audiometry

    The core test - with tympanometry, otoacoustic emissions and speech audiometry to map the pattern and severity.

  5. 05

    Confirming

    MRI IAM with gadolinium

    Mandatory for asymmetric sensorineural hearing loss - rules out acoustic neuroma, CPA lesions and retrocochlear pathology.

  6. 06

    Confirming

    CT temporal bone when needed

    For conductive loss, trauma, cholesteatoma, otosclerosis or congenital anomalies.

  7. 07

    Acting

    Urgent ENT for SSNHL

    A sudden drop needs same-day ENT input - steroids and imaging are most effective inside the first 2 weeks.

Typical timeline: urgent for sudden loss, weeks for gradual work-up.

Symptoms

What one-sided hearing loss feels like.

More than just quieter sound on one side - tinnitus, aural fullness, poor localisation and listening fatigue often travel together.

  • Muffled hearing in one ear

    Voices, television or phone calls sound dull on one side - the classic first symptom.

  • Tinnitus

    Ringing, buzzing or hissing in the affected ear - often the loudest warning sign.

  • Vertigo or imbalance

    Spinning, unsteadiness or a pull to one side - points to labyrinth, vestibular nerve or CPA involvement.

  • Aural fullness

    A blocked or pressurised feeling in one ear - common in Meniere's, effusion and SSNHL.

  • Trouble hearing in noise

    Restaurants and group conversations become exhausting - a hallmark of single-sided deafness.

  • Loss of sound localisation

    Difficulty telling which direction a sound came from - a functional signature of unilateral loss.

  • Otorrhoea or otalgia

    Discharge or ear pain suggests middle ear disease, chronic otitis media or cholesteatoma.

  • Red flag - sudden loss

    A sudden drop in hearing over hours to days is an emergency - do not wait for a routine appointment.

Treatment

How deafness in one ear is treated in the UK.

Treat the cause first - then rehabilitate. Modern options span steroids, surgery, radiosurgery and a range of devices from CROS aids to cochlear implants.

  • Treat the underlying cause

    Everything starts here - wax removal, antibiotics for infection, steroids for SSNHL, surgery for cholesteatoma, imaging for tumours.

  • High-dose steroids for SSNHL

    Oral prednisolone (typically 1 mg/kg to 60 mg for 7 days then taper) within 2 weeks of onset. Intratympanic steroids may be added or used as salvage.

  • Acoustic neuroma pathway

    Observation, stereotactic radiosurgery (gamma knife) or microsurgical resection - a specialist skull base MDT decision.

  • CROS or BiCROS hearing aids

    Contralateral routing of signal - a microphone on the deaf ear sends sound to the better ear. A non-surgical solution for SSD.

  • Bone-anchored hearing aid (BAHA)

    An osseointegrated implant transmits sound through bone to the working cochlea - fitted by an ENT and audiology team.

  • Cochlear implant for SSD

    An emerging and effective option for severe-to-profound single-sided deafness - restores true binaural input and localisation.

  • Middle ear surgery

    Tympanoplasty, mastoidectomy for cholesteatoma or stapedectomy for otosclerosis - restores conductive hearing where possible.

  • Rehabilitation and support

    Vestibular therapy, tinnitus retraining, lip reading, assistive listening devices and workplace adjustments through Access to Work.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, audiologist or ENT surgeon knows your history and audiogram, and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Hearing loss in adults: assessment and management (NG98).

  • British Association of Otorhinolaryngology - Head and Neck Surgery (ENT UK/BAOHNS). Sudden sensorineural hearing loss guidelines.

  • British Society of Audiology. Recommended procedures for pure tone audiometry and tympanometry.

  • Royal National Institute for Deaf People (RNID). Patient information on single-sided deafness and hearing loss.

Red flags

When one-sided hearing loss needs urgent attention.

Most cases can be worked up routinely. These are the situations that cannot wait - and where specialist input is needed quickly.

  • Sudden sensorineural hearing loss

    A drop of 30 dB or more over 3 contiguous frequencies within 72 hours is an emergency - urgent ENT and steroids within 2 weeks.

  • Unilateral loss with tinnitus and imbalance

    Slowly progressive one-sided loss with tinnitus or unsteadiness needs an MRI IAM to exclude an acoustic neuroma.

  • Ramsay Hunt syndrome

    Facial weakness, ear pain and vesicles in or around the ear with hearing loss - urgent antivirals and steroids.

  • Cholesteatoma

    Persistent foul-smelling ear discharge with hearing loss - can erode surrounding structures. Needs ENT and often surgery.

  • Meningitis or intracranial signs

    Fever, neck stiffness, altered consciousness or severe headache with hearing loss - call 999.

  • Head or temporal bone trauma

    Any hearing loss after a significant head injury needs urgent assessment for temporal bone fracture and nerve damage.

  • Unilateral loss in a child

    Congenital or acquired one-sided loss in a child needs specialist paediatric audiology and MRI - early support protects speech and learning.

  • Autoimmune inner ear disease

    Rapidly progressive bilateral or fluctuating loss with systemic features - Cogan syndrome and AIED need rheumatology input.

  • Ototoxic exposure

    Recent aminoglycosides, platinum chemotherapy, high-dose aspirin or loop diuretics - stop or review under specialist advice.

Living with it

A treatable condition, with modern options.

Four things that make the biggest difference day to day - acting fast on sudden loss, choosing the right device, managing listening fatigue and knowing where to turn for support.

A quiet reminder

Rehabilitation is as important as diagnosis.

A named audiologist, a device that suits your life and a workplace plan can do as much for wellbeing as any single treatment.

  1. 01 Act fast

    Sudden loss is time-critical

    If hearing drops over hours or days, seek same-day ENT input. Steroids work best inside the first 2 weeks.

  2. 02 Rehab

    The right device changes everything

    CROS aids, BAHA and cochlear implants can restore usable hearing and spatial awareness - ask for an audiology-led plan.

  3. 03 Noise

    Manage listening fatigue

    Choose seating with your good ear towards conversation, use hearing loops, and take short breaks in noisy places.

  4. 04 Support

    You do not have to do this alone

    RNID, Hearing Link, the Meniere's Society and Acoustic Neuroma UK offer peer support, advice and workplace guidance.

Frequently asked

Everything we get asked about deafness in one ear.

Quick answers on SSNHL, MRI IAM, acoustic neuroma and the devices that restore useful hearing.

  • What causes deafness in one ear?

    Common causes include wax impaction, middle ear infection or effusion, sudden sensorineural hearing loss (SSNHL), acoustic neuroma, Meniere's disease, labyrinthitis, cholesteatoma, otosclerosis, trauma and ototoxic drugs. Any unexplained one-sided hearing loss needs an audiogram and usually an MRI of the internal auditory meati.

  • Is sudden hearing loss in one ear an emergency?

    Yes. Sudden sensorineural hearing loss (SSNHL) - a drop of 30 dB or more across three contiguous frequencies within 72 hours - is an ENT emergency. High-dose oral prednisolone started within 2 weeks of onset gives the best chance of recovery, and an MRI is needed to rule out acoustic neuroma.

  • What is single-sided deafness (SSD)?

    Single-sided deafness is severe-to-profound hearing loss in one ear with normal or near-normal hearing in the other. People with SSD struggle with hearing in noise, sound localisation and listening fatigue. Rehabilitation options include CROS aids, bone-anchored hearing aids and cochlear implants.

  • Why do I need an MRI for one-sided hearing loss?

    An MRI of the internal auditory meati (IAM) with gadolinium is the gold standard for asymmetric sensorineural hearing loss. It rules out acoustic neuroma (vestibular schwannoma), other cerebellopontine angle tumours and retrocochlear pathology. UK BAOHNS guidance recommends it in almost all unexplained cases.

  • Can hearing come back in the deaf ear?

    It depends on the cause. Wax, middle ear effusion and some conductive causes reverse completely. SSNHL recovers partially or fully in a proportion of patients if treated early with steroids. Acoustic neuroma-related loss rarely improves, but rehabilitation with CROS, BAHA or a cochlear implant can restore useful hearing.

  • What is a CROS hearing aid?

    CROS stands for contralateral routing of signal. A microphone worn on the deaf ear picks up sound and transmits it wirelessly to a hearing aid on the better ear. It is a non-surgical option for single-sided deafness that reduces the head shadow effect and improves hearing in noise.

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