Platinum-based chemotherapy drugs are the most common cause of chemotherapy-related hearing loss, with cisplatin being the worst offender. More than a third of adults and up to 60% of children treated with cisplatin develop some degree of hearing impairment. Carboplatin, the other widely used platinum drug, also carries risk, particularly at higher doses or when combined with radiation therapy.
Cisplatin: The Highest-Risk Drug
Cisplatin is used to treat a wide range of cancers, including testicular, ovarian, bladder, head and neck, and lung cancers. It is also the chemotherapy drug most strongly linked to permanent hearing loss. Roughly 36% of adult patients treated with cisplatin develop measurable hearing impairment. In children, that number climbs to 40% to 60%, partly because pediatric patients are monitored more closely, catching cases that might go unnoticed in adults.
The hearing loss cisplatin causes typically starts in the highest-pitched sounds and works its way down to lower frequencies with continued treatment. Because standard hearing tests only measure up to 8,000 Hz, the earliest damage often goes undetected on a conventional audiogram. Tinnitus, a persistent ringing or buzzing in the ears, is frequently the first warning sign. Some patients also experience dizziness or balance problems.
What makes cisplatin-induced hearing loss especially concerning is that it’s usually permanent. The drug kills sensory hair cells in the inner ear, the tiny structures that convert sound vibrations into electrical signals your brain can interpret. Humans don’t regenerate these cells. Cisplatin also damages the tissue that maintains the chemical environment inside the inner ear (called the stria vascularis), which further disrupts normal hearing function.
How Cisplatin Damages the Inner Ear
Once cisplatin enters the cells of the inner ear, it triggers a cascade of destructive events. The drug binds to DNA and other molecules inside the cell, causing direct structural damage. It also floods the cell with harmful molecules called reactive oxygen species by activating an enzyme that is especially abundant in the inner ear. This oxidative stress overwhelms the cell’s defenses, damages its energy-producing structures, and ultimately triggers cell death through several different pathways. The inner ear also has a blood-tissue barrier similar to the blood-brain barrier, and cisplatin can compromise its integrity, making the ear even more vulnerable to damage over time.
Carboplatin and Other Platinum Drugs
Carboplatin is generally considered less ototoxic than cisplatin at standard doses, but it still poses a risk. High-dose carboplatin regimens, particularly those used in bone marrow transplant protocols, can cause significant hearing loss. The risk also increases substantially when carboplatin is combined with cranial radiation, a scenario common in pediatric brain tumor treatment.
Oxaliplatin, a third platinum-based drug used primarily for colorectal cancer, appears to carry a lower hearing loss risk than either cisplatin or carboplatin, though isolated cases have been reported.
Non-Platinum Drugs With Hearing Risks
Platinum drugs get the most attention, but they aren’t the only chemotherapy agents linked to hearing problems. Vincristine, a drug commonly used in childhood leukemia and lymphoma, is a known ototoxin. Other drugs in the same family, called vinca alkaloids, including vinorelbine and vinblastine, are suspected ototoxins as well, though the evidence is less definitive.
The risk compounds when these drugs are given alongside cisplatin. Lab studies have shown that combining cisplatin with vincristine or vinorelbine produces synergistic damage to hair cells, meaning the two drugs together are far more destructive than either one alone. Nitrogen mustard derivatives, an older class of chemotherapy drugs, are also recognized ototoxins.
Hearing Loss Can Progress After Treatment Ends
One of the more unsettling findings about chemotherapy-related hearing loss is that it doesn’t always stop when treatment does. In one study of children treated with cisplatin, about 24% of ears showed worsening hearing thresholds during follow-up testing after chemotherapy was already complete. This post-treatment decline was most significant at 4,000 Hz, a frequency critical for understanding speech. Children who already had some hearing damage at the end of treatment were the most likely to experience further deterioration.
If you also received radiation to the head or neck alongside chemotherapy, hearing loss can continue to progress for a year or two after treatment. This delayed progression is one reason audiologists recommend continued monitoring well beyond the last chemotherapy cycle.
Who Faces the Greatest Risk
Several factors influence how severely chemotherapy affects your hearing. The specific drug matters most, but cumulative dose plays a major role as well. Higher total doses of cisplatin are associated with more severe and more widespread hearing loss. How the drug is administered also matters: the rate and schedule of infusions can influence ototoxicity.
Age is a significant factor. Young children are particularly vulnerable, and the consequences are more far-reaching because hearing loss during critical developmental windows can delay speech, language, and cognitive development. Reduced kidney function increases risk too, since the kidneys are responsible for clearing platinum drugs from the body. When clearance is impaired, the drug lingers longer and reaches higher concentrations in the inner ear. Prior noise exposure and pre-existing hearing loss also lower the threshold for additional damage.
Monitoring During Treatment
The American Academy of Audiology recommends a baseline hearing test before the first dose of any platinum-based chemotherapy. Follow-up testing should happen before each subsequent treatment cycle, after any temporary hearing changes have had time to stabilize. High-frequency audiometry, which tests above the standard 8,000 Hz range, is especially valuable for catching the earliest signs of damage before it reaches the frequencies you rely on for conversation.
Because hearing loss can develop or worsen after chemotherapy ends, a follow-up hearing test a few months after the final dose is standard practice. If radiation to the head or neck was part of your treatment plan, monitoring for one to two additional years is advisable. Any time a shift in hearing is detected, a full audiologic evaluation helps confirm whether the change is related to the chemotherapy or something else, like fluid buildup in the middle ear.
Protection and Management Options
In September 2022, the FDA approved sodium thiosulfate (sold as Pedmark) to reduce the risk of cisplatin-related hearing loss in children aged one month and older who have localized, non-metastatic solid tumors. This is currently the only FDA-approved protective agent for chemotherapy-induced hearing loss, and its use is limited to specific pediatric populations. No equivalent protection has been approved for adults.
For hearing loss that has already occurred, the standard options are hearing aids and, in severe cases, cochlear implants. The grading systems doctors use to classify the severity of chemotherapy-related hearing loss help guide these decisions. Loss is typically graded on how far down the frequency range the damage extends and how loud sounds need to be before they’re detected. When hearing thresholds exceed 50 decibels at the frequencies important for everyday speech (1,000 Hz and above), a cochlear implant may be considered.
If you’re currently receiving platinum-based chemotherapy and notice ringing in your ears, a sense of fullness, difficulty hearing in noisy environments, or trouble following conversations, these are worth reporting to your treatment team promptly. Catching ototoxicity early gives your oncologist the option to adjust dosing, switch agents, or alter the treatment schedule before the damage becomes more severe.