What is sudden hearing loss and why does it happen?

Sudden hearing loss (also known as sudden sensorineural hearing loss or SSHL) is the term for hearing loss that occurs all of a sudden, or over the course of just a few days. It can be a frightening and disorienting experience that warrants immediate medical attention.

According to research published in The Hearing Journal, 1 out of 5,000 adults experience sudden-onset hearing loss annually, though that number could be much higher due to the number of cases that go unreported and undiagnosed.

Sudden hearing loss is a medical emergency

If you or a loved one has suddenly developed hearing loss, see your doctor or make an appointment with an ENT physician right away as early intervention can improve the chances that you recover your hearing. 

Sudden hearing loss that occurs alongside symptoms like weakness, dizziness, or difficulty speaking may indicate a stroke and requires emergency medical attention.

Symptoms of sudden hearing loss

Sudden hearing loss usually only affects one ear. Some people wake up to find their hearing has changed overnight. Others don’t notice a difference until they hold the phone up to the affected ear or try to listen to headphones.

In some cases SSHL is preceded by a very noticeable “pop," which can be quite alarming.

Afterward, some patients feel a fullness in the affected ear. People may also notice a strange feeling on that side of the head, sometimes accompanied by sudden ringing in the ear (tinnitus) and dizziness. This is sometimes called "aural fullness."

Testing for sudden hearing loss

See a medical provider right away. They will check your ears, go over your symptoms, and possibly run blood and imaging tests, as well as a hearing test. Doctors will diagnose SSHL if a hearing loss of at least 30 decibels occurs in at least three connected frequencies.

If any of your healthcare providers are unwilling to thoroughly investigate your sudden hearing loss, don't hesitate to seek a second opinion.

Treatment with steroids may restore hearing

The primary treatment for sudden hearing loss are steroids called prednisolone and dexamethasone, which help reduce inflammation and swelling in the inner ear.

Usually administered in pill form, steroids also can be given through an injection behind the eardrum, or intravenously (into a vein).

While sometimes doctors give high doses of steroids, the latest research indicates that standard doses are likely just as effective while causing fewer side effects.

In addition to steroids, hyperbaric oxygen therapy is emerging as a potential treatment that may help restore hearing.

Batroxobin is another treatment that is sometimes used in cases sudden hearing loss. It is an enzyme derived from snake venom which can help improve blood flow and reduce clotting. While recent research has been promising, more needs to be done to determine its overall effectiveness.

If an underlying cause for your SSHL is identified—such as an infection—additional treatments, like antibiotics, may be necessary.

Don't delay getting help

The window to restore hearing typically closes within two to four weeks after the onset of sudden hearing loss. After that short window, the hearing loss is likely to become permanent and irreversible.

While the good news is that about 50% of people will spontaneously recover some or all of their hearing within one to two weeks, seeking prompt medical attention maximizes the chances of recovery for those who don’t naturally regain their hearing.

What if my hearing doesn't come back?

Unfortunately, some cases of SSHL do turn into permanent hearing loss. In about 15% of cases, permanent single-sided deafness is the outcome, even with treatment. If the damage to your hearing is permanent, your treatment will shift towards amplifying any remaining hearing ability you might have in the affected ear.

Depending on the degree of hearing loss, treatment options include:

• Hearing aids
• Bone anchored hearing aids (BAHAs)
• CROS hearing aids if the hearing loss is profound or severe.

While none of these treatments can return your hearing to as it was before, they can help make it easier to process sounds and communicate with others.

Potential causes

It's often not clear what causes sudden hearing loss. In fact, only 10-15% of diagnosed cases will have a clear cause. However, there are some known risk factors, including:

• Bacterial and viral infections
• Inner ear disorders, especially Meniere's disease
• Migraines
• Tumors (e.g. acoustic neuroma)
• Certain medications
• Neurologic diseases or disorders (e.g. multiple sclerosis)
• Head injury or trauma
• Autoimmune inner ear disorder and other autoimmune diseases
• Thyroid problems
• Circulation issues (e.g. vasculitis)

Researchers suspect a link to viral infections

Researchers think that in cases of sudden hearing loss where no obvious cause can be identified, a mild viral infection may have been to blame. This is because people often report having a head cold or respiratory infection in the days and weeks before they lost their hearing.

How would it do this? The virus itself—or the resulting inflammation—somehow damages the inner ear's delicate hair cells and/or the blood supply.

Any number of viruses may be responsible, including some that may not produce many symptoms, meaning a person is unaware they're sick until they experience hearing loss. This is an area of emerging research.

Quite a few more serious viruses, some of them life-threatening, can cause hearing loss, either gradual or sudden. Many of them can be prevented by vaccines, including measles, mumps and rubella, and chickenpox (varicella). Because these illnesses often produce widespread severe symptoms, these cases are easier to catch and treat earlier.

Connect with a hearing specialist near you

Most hearing loss comes on gradually instead of suddenly. While it doesn't require emergency treatment, early intervention still makes a big difference.

Seeing a hearing specialist can help identify the cause, discover treatment options, and improve your quality of life. If you or a loved one notice changes in hearing, don’t wait—find a hearing clinic near you and take the first step toward better hearing health.