Ototoxic Medications That May Cause Hearing Loss

Ototoxicity refers to chemical-induced damage to the inner ear. The damage can either be permanent or temporary, causing hearing loss or balance disorders. While medications are taken for their established benefits, all medications have side effects that you should be aware of before taking. Hearing loss related to consuming an ototoxic medication is one reason that your healthcare provider may have you stop taking a drug in relation to lifestyle disturbance.

Hearing loss is most commonly associated with six different categories of medications. The following may be associated with permanent hearing loss:

• Aminoglycoside antibiotics
• Platinum-based chemotherapy

Medications that are more likely to cause temporary hearing loss:

• Loop diuretics
• Quinine
• Salicylates
• Vinca alkaloids

Many of the medications mentioned above can also harm the kidney (nephrotoxic) and require your healthcare provider to check your blood regularly to assess your kidney function. If you notice any changes in your hearing, you should always seek help from your prescribing physician.

Risk for Ototoxicity

The prevalence for having ototoxicity is not well documented, however, both temporary and permanent damage from ototoxicity is known. Certain medications will have more information than others and will be described in their subsequent sections.

Likewise, there is not much understanding of how to prevent ototoxicity from occurring. Some medications with increased risk for ototoxicity like some antibiotics will require blood work known as a "peak and trough" to be drawn.

The peak is the level of the drug when it should be at its highest concentration in the blood. A trough is the level of the drug when it should be at its lowest concentration. While closely monitoring this may help maintain the therapeutic effect, it does not guarantee that you will not have issues with ototoxicity.

Other factors that may contribute to ototoxicity include:

• Dose, length of treatment, and the overall amount received
• Kidney failure
• Taking other ototoxic medications at the same time
• Genetic predisposition to ototoxicity

Symptoms Related to Ototoxicity

The symptoms related to ototoxicity greatly depends on what part of the inner ear has been damaged. Damage to the inner ear can occur to either your cochlea (referred to as cochleotoxicity) or your vestibular complex (referred to as vestibulotoxicity). In both cases, the symptoms all relate to damaged sensory cells.

If your cochlea is damaged, your hearing will be impaired. The level of impairment directly correlates to the extent of damage resulting in mild tinnitus to complete hearing loss. Hearing loss can either affect one or both ears.

If the ototoxicity affects the vestibular complex, your balance will be affected. Like damage to your cochlea, damage can affect one ear or both ears. If the damage occurs rapidly to one ear, you will likely experience:

• Vertigo
• Vomiting
• Uncontrolled eye movement (nystagmus)

Symptoms that occur rapidly may cause you to be bed-bound until the symptoms resolve gradually. If the damage occurs to both sides of your ear, you may experience:

• Headache
• Ear fullness
• Imbalance affecting your ability to walk
• Blurred vision that appears jerky (oscillopsia)
• Intolerance to head movement
• Walking with a wide stance
• Difficulty walking in the dark
• Unsteadiness
• Lightheadedness
• Fatigue

If the damage to your vestibular complex is severe, oscillopsia and difficulty walking at night will not improve. The other symptoms will likely improve over time. With severe damage, you can recover from the majority of the balance-related symptoms because of your body's ability to adapt.

Aminoglycoside Antibiotics

Aminoglycoside antibiotics are an important group of medications for bloodstream and urinary tract infections as well as resistant tuberculosis. Medications include:

• Gentamicin
• Tobramycin
• Streptomycin

Aminoglycoside antibiotics have a risk of approximately 20% for developing hearing problems and approximately 15% risk for developing balance problems. The risk for developing problems related to ototoxicity increases if you are taking a loop diuretic (like Lasix) or vancomycin (an antibiotic) at the same time.

Loop Diuretics

Loop diuretics cause an increase in the volume of urine production. This is helpful in congestive heart failure, high blood pressure, and kidney failure. Common medications include:

• Lasix (furosemide)
• Bumex (bumetanide)

Loop diuretics have a generally low risk of ototoxicity but it may occur in as many as six out of every 100 people using the medication. It is generally assumed to occur at higher doses resulting in a blood concentration of about 50 milligrams (mg) per liter.

Platinum-Based Chemotherapy

Cisplatin and Carboplatin are two of the main chemotherapy drugs (antineoplastics) that are ototoxic. They are commonly used for the treatment of various cancers including:

• Ovarian and testicular cancer
• Bladder cancer
• Lung cancer
• Head and neck cancers

Quinine

Quinine is used to treat malaria and leg cramps. Longer treatments with this drug can result in high-frequency hearing loss, which is often considered permanent if hearing loss of normal conversation is experienced. Quinine also commonly causes hearing loss associated with a syndrome called cinchonism:

• Deafness
• Vertigo
• Ringing in your ears
• Headache
• Loss of vision
• Nausea

Salicylates

Salicylates such as aspirin have risk of ototoxicity at higher doses and may result in hearing loss commonly in the 30 decibels range, which is the equivalent of whispering. However, damage can range as low as mild tinnitus at lower doses of aspirin. Younger men, in particular, appear to be at risk for hearing loss related to aspirin use.

Vinca Alkaloids

Vincristine is a medication for the treatment of acute lymphocytic leukemia (ALL), Hodgkin lymphoma, and other cancers. This medication is particularly associated with a high risk for causing hearing loss when used concomitantly with aminoglycoside antibiotics.

Diagnosing Hearing Loss Related to Ototoxicity

You should see an audiologist for a baseline audiogram before undergoing therapy with medication at risk for ototoxicity. Your healthcare provider will then determine if a regularly scheduled audiogram will need to be performed or a simple self-assessment of your hearing. While this will not prevent hearing loss related to ototoxicity, it will help you identify problems early.

Treatment

There are not currently any treatments available to reverse permanent damage to the inner ear. The most important thing is to diagnose it early and stop the ototoxic medication immediately if possible.

If the hearing loss is in both ears, or on one side, and is mild, moderate, or severe, your healthcare provider may recommend hearing aids. If the hearing loss is on both sides and is profound, your healthcare provider may recommend a cochlear implant. Rehabilitation is commonly the treatment of choice if you are suffering from either temporary or permanent balance disorders.