For many individuals with asthma, exposure to some odors – such as perfume – can increase inflammation of the airways. But according to a new study by researchers from the Monell Chemical Senses Center in Philadelphia, PA, just believing an odor will cause harm, even if it contains no irritants, can have the same effect.

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Does perfume worsen your asthma? Researchers say it could be the fear that an odor can be harmful, rather than the odor itself, that can trigger airway inflammation in asthmatics.

The research team, led by Cristina Jaén, PhD, a physiologist at Monell, recently published their findings in the Journal of Psychosomatic Research.

Asthma – a chronic lung disease characterized by inflammation and narrowing of the airways – affects more than 25 million people in the US. Symptoms of the disease include coughing, wheezing, shortness of breath and chest tightness.

Because the airways of asthmatics are sensitive, symptoms can be caused by certain “triggers,” including dust, pollen, allergens and chemical irritants.

According to Jaén and colleagues, many health organizations cite that certain scents and fragrances – such as perfume or hairspray – can trigger symptoms of asthma. They note that this can cause patients to worry that their asthma will flare up when they are exposed to such odors.

The team wanted to determine whether anxiety surrounding exposure to odors may contribute to the development of asthma symptoms.

For their study, the researchers enrolled 17 participants with moderate asthma and exposed them to an odorant called phenylethyl alcohol (PEA) for 15 minutes.

According to the researchers, PEA has a rose fragrance and is a deemed a “pure” odorant that has no physiological irritant elements.

Before PEA exposure, eight of the participants were told that the odor may have therapeutic properties, while the remaining nine participants were told that the odor could cause mild respiratory issues.

The team found that the participants who were told that PEA exposure could be harmful rated the odor as being more irritating, compared with those who were told it could be therapeutic.

Furthermore, participants who believed the odor could cause harm experienced immediate airway inflammation, and to the team’s surprise, this inflammation remained 24 hours later. No such inflammation was found among participants who believed the odor may be therapeutic.

The researchers believe their findings indicate that the effects of fragrances on asthma may be related to the expectation that the odor can cause harm, rather than the odor itself.

Jaén says:

It’s not just what you smell, but also what you think you smell. Asthmatics often are anxious about scents and fragrances. When we expect that an odor is harmful, our bodies react as if that odor is indeed harmful. Both patients and care providers need to understand how expectations about odors can influence symptoms of the disease.”

Study co-author Pamela Dalton, PhD, told Medical News Today that the team also believes the study findings are consistent with previous studies showing an association between stress and asthma exacerbation:

“While we did not find a direct effect on stress ratings of our manipulation, we clearly aroused anxiety and worry among the group receiving the asthmogenic characterization and this may have tapped into the same pathways that stress does,” she explained.

The researchers say they now want to investigate the biological mechanisms underlying the association between harmful odor expectation and airway inflammation.

“We also want to manipulate behavioral strategies to mitigate such responses, as well as understand whether there are individual differences among asthmatics in how they manifest this response,” Dalton told us.

Earlier this year, Medical News Today reported on a study published in the journal Clinical & Experimental Immunology, which suggested that reduced exposure to “healthy microbes” in rural environments could increase the risk of asthma and allergies.