For three months, a 55-year-old woman had a dry cough she could not shake. Then she began coughing up large amounts of blood. Imaging showed a soft-tissue mass blocking the airway to the lower part of her left lung, and that section of lung had completely collapsed, a combination doctors often associate with lung cancer. The explanation her doctors eventually settled on was far more surprising: the concentrated peroxide gel used to whiten her teeth.
The case was published in January in Cureus by pulmonology and forensic medicine specialists at Laghouat Public Hospital in Algeria. The authors write that airway lesions caused by hydrogen peroxide exposure are exceedingly rare.
A Whitening Session That Went Badly
The woman had no history of smoking, chronic lung disease, or bleeding disorders. Her symptoms began shortly after a dental whitening procedure that used 35% hydrogen peroxide.
The procedure did not go smoothly. It was complicated by intense throat pain, ulcer-like sores, and severe coughing. The dry cough that followed lasted about three months and was accompanied by an earlier, smaller episode of coughing up blood. Her shortness of breath worsened until she was breathless even at rest, and then a massive bleeding episode brought her to the hospital. Her doctors identified the whitening exposure only in retrospect.
A Blockage with the Hallmarks of Cancer
Chest imaging showed complete collapse of the lower lobe of her left lung. The cause was a soft-tissue lesion sitting inside the airway, and there was also an area of consolidation, or filled-in lung tissue, nearby. A lingering cough, blood in the sputum, and a collapsed lobe can all point toward a tumor, which is why cases like this create real diagnostic uncertainty.
Doctors attempted a flexible bronchoscopy, threading a camera into her airways, but had to stop because of complications. Afterward, she coughed up thick mucus. She received etamsylate, a medication used to help control bleeding, and was monitored overnight. Because she stayed stable with no further bleeding, she went home the next day with advice to undergo a repeat bronchoscopy under general anesthesia at a referral center.
She never had it. Her recovery over the following months was uneventful, and she declined further invasive procedures. According to the full case report, a follow-up chest CT four months after her symptoms began showed the lesion had completely disappeared and her left lung had fully re-expanded, with only minor scarring. She had no recurrence of cough or bleeding.
Why Concentration Matters
Hydrogen peroxide is a powerful oxidizing chemical used widely in medicine and dentistry, for everything from disinfecting surfaces to bleaching teeth, and strength makes a large difference. The report notes that at-home whitening products typically contain 3% to 10%. The gel used on this patient was 35%. The Agency for Toxic Substances and Disease Registry says household hydrogen peroxide is usually 3% to 9%, and it warns that inhaling vapors from solutions stronger than 10% may cause severe lung irritation. Even household-strength 3% hydrogen peroxide can irritate the airways when inhaled, the agency notes.
International poison information guidance hosted by INCHEM similarly notes that inhaled hydrogen peroxide usually causes brief coughing and shortness of breath, while concentrated solutions can cause more severe irritation and inflammation of the airways.
The Algerian authors propose that some of the whitening solution was aspirated into her airways, injuring the lining and producing inflammation and thick secretions that built into a mass-like obstruction. Coughing up that material would help explain why the apparent tumor vanished without surgery or cancer treatment.
Hydrogen peroxide has caused lung trouble in other settings, too. Physicians at the University of Nevada, Las Vegas described acute pneumonitis in an 82-year-old man who had been adding hydrogen peroxide to the humidifier of his sleep apnea machine. He had started doing so on a friend's advice to prevent COVID-19, and his lung findings were initially thought to be COVID-19 pneumonia. He improved after treatment with steroid medication.
What One Case Can and Cannot Show
This is a single patient, and the evidence is circumstantial. The authors describe the whitening exposure as a plausible mechanism for her airway injury, not a proven cause. Because the bronchoscopy was interrupted and never repeated, the blockage was never fully examined, and other explanations cannot be completely excluded.
The report also stresses that hydrogen peroxide whitening is generally considered safe when applied under professional supervision. Nothing in the case suggests that routine whitening poses a common lung risk.
The authors' main message is aimed at clinicians: when a patient has unexplained bleeding from the airways or a collapsed section of lung, asking about recent exposures, including cosmetic dental procedures, could prevent an inflammatory blockage from being mistaken for cancer.
Anyone who develops severe throat pain, persistent coughing, or breathing trouble after a dental or cosmetic procedure should tell their doctor. Coughing up blood always warrants prompt medical attention.
Key Questions Answered
What happened to the patient?
After a whitening procedure with 35% hydrogen peroxide, she developed a lasting cough and later severe bleeding from her airways. Imaging showed a tumor-like blockage and a collapsed lung lobe.
Did she have lung cancer?
There was no evidence of cancer. The blockage cleared, and follow-up imaging four months after her symptoms began showed her lung had fully re-expanded.
How strong was the whitening gel?
It contained 35% hydrogen peroxide. The report notes at-home whitening products typically contain 3% to 10%.
Is teeth whitening dangerous for the lungs?
This is a single, unusual case, and the authors did not prove the whitening caused the injury. Professionally supervised whitening is generally considered safe.
What symptoms should prompt a doctor visit?
Severe throat pain, an ongoing cough, or shortness of breath after any dental or cosmetic procedure should be reported. Coughing up blood needs prompt medical care.
Published by Medicaldaily.com
