Ototoxic drugs: Medications that may harm hearing

When illness finally starts to fade, the last thing anyone expects is for their hearing to go with it. But for many people, the road to recovery takes an unexpected turn when the medication that helps them heal causes hearing loss or tinnitus (ringing in the ears) as a side effect.

The phenomenon is called ototoxicity. Combining "oto" (meaning "ear") and "toxicity" (meaning "poisoning"), the term describes inner ear damage resulting from drug side effects that can affect hearing and sometimes balance.

Often the changes are irreversible, so it's wise to learn which medications can lead to these effects, says Dr. James Naples, an otolaryngologist (ear, nose, and throat specialist) at Harvard-affiliated Beth Israel Deaconess Medical Center.

"It's very uncommon over all, but there are a growing number of drugs that have ototoxicity as a known side effect," Dr. Naples says.

Drugs linked to tinnitus and hearing loss

What drugs are on the list? Medications more likely to cause ototoxicity include

• macrolide antibiotics such as azithromycin and clarithromycin, when prescribed for a long period of time, especially at high doses
• aspirin and other salicylates in high doses
• certain chemotherapy drugs such as cisplatin and carboplatin (Kyxata)
• loop diuretics such as furosemide (Lasix), which are used for conditions such as heart failure and kidney disease
• some biologics, which are derived from living organisms and include immunotherapy, gene therapy, and disease-modifying drugs.

Notably, cases of ototoxicity are likely to grow in the years ahead as biologics are increasingly prescribed for an array of conditions, from melanoma to thyroid eye disease, Dr. Naples says. "We are learning recently that many of the newer biologic agents have ototoxicity occurring as a side effect," he says.

Damaging effects

Who's vulnerable to ototoxicity? It depends not only on the type of medication, but in some cases the dose and how long you've been taking it. Using a combination of ototoxic drugs also increases the odds of hearing issues, Dr. Naples says. For example, taking cisplatin and furosemide together might cause much greater hearing loss than taking either drug alone.

Regardless, most of the offending drugs are given in high doses, and often while someone is hospitalized. "Many of these drugs aren't something a lot of people take day to day," he says, "although this may change with the use of more biologic agents."

When ototoxicity happens, the damage is typically noticed quickly - "during the administration of the drug or just after," Dr. Naples says. "Usually someone's getting chemo, for instance, and shortly afterward they report this effect. It's not six months down the road."

Many ototoxic drugs damage hearing by injuring the hairlike projections in the inner ear that convert sound vibrations into electrical signals the brain can interpret. "But different drugs have different likelihoods of affecting different parts of the inner ear," Dr. Naples says.

Ototoxic drugs can also affect balance by damaging the vestibular system - the part of the inner ear that senses motion and helps us stay oriented in space.

Because the damage might not be reversible, doctors may prescribe a corticosteroid drug like prednisone in addition to stopping the offending drug. Corticosteroid drugs help reduce inflammation in the inner ear and protect the delicate structures there before more are harmed.

Stemming the effects

Managing ototoxicity is a delicate dance. Most doctors choose medication dosing to maximize a drug's benefits while minimizing potentially ototoxic side effects. And since many of these medicines treat serious conditions, it's not always possible to find an alternative.

"The caveat to that is that someone may lose so much hearing they can't communicate or navigate their world, but that's very uncommon," Dr. Naples says. "Usually we can adjust the dosing of the medication a little to try to avoid any worsening."

If you suspect a problem, don't stop taking a medication on your own - talk to your doctor immediately. Describe your symptoms, and ask if your dose can be adjusted or if you can take an alternative drug.

But the most important thing, Dr. Naples says, is to get your hearing checked (usually by an audiologist) before, during, and after taking a known ototoxic medication.

"It's the only way to address the problem," he says. "Otherwise you're playing catch-up, and it becomes difficult to know which effects are from the medication and which are possibly due to prior hearing loss."

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