Drug labels routinely describe myriad potential side effects stemming from taking a given medication.

Yet, one newly recognized risk usually goes unmentioned: hearing loss. “There are a number of common medications that are ototoxic, which means harmful to the ears,” says Dr. Sharon Curhan, a physician and epidemiologist at the Channing Division of Network Medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston. That side effect isn't typically listed on drug labels, she says. "These are relatively new findings.”

Research by Curhan and others finds that some over-the-counter medications, acetaminophen (the generic name for Tylenol), ibuprofen and prescriptions, ranging from certain antibiotics to chemotherapy drugs, can damage hearing. In all, there are more than 200 known ototoxic medications on the market today, according to the American-Speech-Language-Hearing Association, which can also impact the ear's balance functions.

Curhan and colleagues previously found that women who took either ibuprofen or acetaminophen regularly – two days per week or more – had a higher risk of hearing loss, compared with women who took these medications less than once per week; and they found that the magnitude of risk tended be greater with increasing frequency of use. In another study, Curhan and fellow researchers observed a similar association in men, for whom taking aspirin two or more days a week was associated with a higher rate of hearing loss as well. “We didn’t observe any association between regular, moderate dose of​ aspirin use and hearing loss in women,” Curhan says.

However, she and other experts say high doses of aspirin – above recommended daily levels – are commonly associated with temporary, reversible hearing loss that typically subsides ​after a person stops taking aspirin.

And many drugs can cause permanent hearing loss by damaging the sensory hair cells that are used for hearing, located in the inner ear. The loss or death of those hair cells in the cochlea, a sensory organ that translates sound into nerve impulses that go to the brain, can impair hearing.​

Dr. David Haynes, professor of otolaryngology, neurosurgery and hearing and speech sciences at Vanderbilt University Medical Center in Nashville, Tennessee, says multiple factors may contribute to medication-related hearing loss. “But the ultimate is the death of the inner ear hair cells,” he says. “If you don’t have inner ear cochlear hair cells, you’ll have a significant reduction in your hearing. If you don’t have any ear [hair cells], you’ll be deaf.”

Until relatively recently – less than a decade ago by Haynes' reckoning – ear drops that medical providers routinely used in patients contained antibiotics called aminoglycosides, like neomycin​, which are now known to potentially cause hearing loss. “We’d put them directly into the ear because we needed to treat an organism in there called pseudomonas," he says, The hard-to-treat bacteria can cause everything from mild ear infections to more harmful, serious infections. ​ ​

Though it’s not known how many people’s hearing has been damaged by aminoglycoside-containing ear drops, Haynes says most agree the incidence of hearing loss seems to overall have been low. “If there is active infection, even with a hole in the eardrum, [using the ear drops is still]​ ​probably safe, as the round window to the inner ear is impermeable," he says.

Still, Haynes notes, other ear drop options now exist to treat ear infections without using drugs that are potentially harmful to hearing; and using those newer ear drops has become the standard of practice. Even so,​ he adds: “Some M.D.s will use eye drops off-label in the ear for ear infections; [those] that contain aminoglycosides​ ​are potentially ototoxic.”

In addition, aminoglycosides are still sometimes used to treat infections outside the ear,​ such as meningitis and bacterial infections resistant to other drugs. Experts say patients should be aware that those have the potential to cause hearing loss. As a result of the potential for these drugs, like gentamicin, to cause inner ear and kidney damage, among other side effects, doctors tend to use other less toxic antibiotics instead whenever possible.

For cancer patients, some chemotherapy drugs can also lead to hearing loss. But when treating a life-threatening illness, often there aren't any alternatives to drugs with serious side effects, says Dr. Marlan Hansen, an associate professor in the Department of Otolaryngology–Head and Neck Surgery ​and a neurologist, whose specialization includes treating disorders of the inner ear, at University of Iowa Hospitals and Clinics in Iowa City, Iowa.

For some patients, certain chemotherapy drugs, such as cisplatin or carboplatin, which are known to cause hearing loss, end up being exactly what the doctor ordered to kill the cancer. “Invariably, if you get enough cisplatin or​​ carboplatin, you’re going to have ... some degree of hearing loss,” Hansen says. “Better to lose some hearing than be dead.” However, he adds, depending on factors like the severity of the cancer, an oncologist may decide to alter dosing or the duration a patient receives the drug, or switch to a different drug that isn’t toxic to the ears.

Additionally, he notes that some prescription painkillers, such as Vicadin and Percocet, which contain acetaminophen, have also been linked to hearing loss, particularly in high doses and taken over a long period. “There’s a lot of people who [experience] sudden deafness, profound deafness, from taking significant doses of Vicadin over several months or years, and all of the sudden, one day – or within a day or two – they lose all hearing.”

He adds that while it hasn’t been proven, certain drugs taken to treat erectile dysfunction, such as Cialis and Viagra, may contribute to hearing loss. “Those may cause sudden hearing loss – in one ear, typically. We don’t understand the mechanism for that,” he says. “But that’s been reported and at least the [Food and Drug Administration has] come out with a warning about it.”

Fortunately, experts say, patients can take steps to reduce medication-related hearing loss, while still getting the treatment they need. Curhan’s research continues on modifiable risk factors for hearing loss through the ongoing CHEARS: Conservation of Hearing Study​​, for which she and her colleagues are examining data from three major ongoing studies based on nearly 200,000 participants.​

“Hearing loss is often considered to be an inevitable part of the aging process and one of the things that we found in our work is that much of hearing loss … can be prevented or at least its progression can be delayed,” she says. “There are actually a number of modifiable factors, which means things that we can change, to help prevent hearing loss.”

That’s in addition to factors, such as age and genetics, which can also affect hearing loss. “We found that maintaining a healthy weight, staying physically active, eating a healthy diet that includes fish ... not smoking and limiting the use of certain medications that can be harmful to your hearing" – such as over-the-counter pain relievers, including acetaminophen and ibuprofen – "​all of these are potentially modifiable lifestyle factors that can help reduce the risk of hearing loss,” Curhan says.

In addition, she notes that certain vitamins may also have a role to play. Based on a study of predominately non-Hispanic white women, she and fellow researchers concluded that higher intake of beta-carotene, beta-cryptoxanthin and folate, whether from diet and supplements or from diet alone, and avoidance of vitamin C supplements might ​help in the prevention of hearing loss. "It’s not yet known whether these findings will apply to other populations," she adds, and "merits further study."

In addition, she emphasizes the importance of talking with your health care provider about any medications – over-the-counter or prescription – you’re taking, and asking about the potential impact they could have on hearing.

“The bottom line here is that many of these medications clearly have benefits with short-term use and, when used as directed under the appropriate medical supervision, can be extremely effective forms of treatment,” Curhan says. “However, if individuals find a need to take these types of medications regularly, they should consult with their health care professional to discuss the risks and benefits and to explore other possible alternatives.” That includes non-drug treatments.

Experts also say it’s important to have your hearing monitored, if there’s concern that your medications could cause hearing loss – and to adjust treatment, if possible, to prevent further hearing loss if it occurs. Talk to your doctor about any issues with balance, too, which may similarly result from a drug’s effects on the inner ear.

“I think the biggest thing is open communication with their physician and pharmacist to make sure that those providers know all the medications that patients are taking,” adds Carly Brown, pharmacy operations manager for inpatient services with The University of Kansas Hospital in Kansas City, Kansas. “That’s very important because sometimes there can be additive [hearing] loss, and the physician will increase monitoring for those patients – doing auditory tests and balance tests – to make sure that they catch any declines in hearing early on and can possibly change medication regimens in order to prevent further loss.”