Menthol cigarettes might taste better than regular tobacco but are no safer and might lead to more severe lung problems, a new study suggests.

Smokers who reported using menthol cigarettes had more trips to the emergency room and more hospitalizations or treatment for severe worsening of their lung disease compared to people smoking regular tobacco, the study found.

These worsenings, or “exacerbations,” might include difficulty breathing or a major increase in phlegm that lasts for days.

“We were surprised that menthol smokers, compared to non-menthol cigarette smokers, reported more severe exacerbations and had a greater odds of experiencing severe exacerbations,” said Dr. Marilyn Foreman of the Morehouse School of Medicine in Atlanta, Georgia, one of the study authors, in an email to Reuters Health.

She and her colleagues compared 3,758 menthol smokers and 1,941 regular smokers, ages 45 to 80, who smoked at least 10 packs of cigarettes per year. The menthol smokers were slightly younger and more likely to be female and black, they found.

At first glance, it seemed that the menthol smokers had less chronic obstructive pulmonary disease (COPD), and they were less likely to have chronic cough or chronic sputum production and less likely to use medications to help them breathe.

Overall, the two groups had similar frequencies of COPD exacerbations during the average 18-month period of the study, according to the report of the study in the journal Respirology.

But the menthol smokers had more frequent severe exacerbations: 0.22 per year, versus 0.18 per year among smokers of regular tobacco cigarettes.

The menthol smokers also did worse on a test of how far they could walk in six minutes, and they were more short of breath than people who smoked regular cigarettes.

When the researchers took other patient factors into account, such as age and other diseases, there were no longer any differences between the menthol and regular tobacco smokers in lung function, exercise capacity, or breathing problems.

There was still, however, a 29 percent higher risk of severe lung disease exacerbations with use of menthol cigarettes.

The researchers think menthol might have an anesthetic effect on the airways, and as a result, it might take longer to recognize that smokers’ lung disease is worsening, said Foreman.

She and her colleagues admit, though, that their study can’t prove menthol is responsible for making smokers’ lung problems worse.

“In general in the article, the people who smoked menthol cigarettes were different, younger, more likely to be African-American and female,” Dr. Sean Forsythe said in a phone interview with Reuters Health.  “So maybe the differences weren’t due to menthol but were due to the fact that the patients were different.”

Forsythe, who is division director of Pulmonary and Critical Care Medicine at Loyola University Medical Center in Maywood, Illinois, said that while exacerbations appeared to be worse for the menthol smokers, only a longer study could say for sure.

“That’s the type of thing where only following these patients for a year and a half is going to become a bit misleading,” said Forsythe, who wasn’t involved with Foreman’s study.  “If you’re looking for some of these bigger outcomes in the COPD world, maybe you need to follow them longer,” he added.

Foreman pointed out frequent exacerbations might end up having a long-term effect.

“Frequent exacerbations do affect quality of life and may result in greater loss of lung function over time,” said Foreman.

Both agreed the results send an important message to smokers.

“If one thinks that smoking menthol cigarettes is safer, that’s completely inaccurate,” said Forsythe.

It would be as if there were a group of people slowly poisoning themselves with arsenic and then you would compare if cherry flavored arsenic was safer.

“It’s still arsenic,” said Forsythe.