FRIDAY, Aug. 13 (HealthDay News) -- Teens from around the world
who regularly take acetaminophen, best known as Tylenol, were more
than twice as likely to have asthma as teens who never take the
over-the-counter pain and fever reducer, new research finds.
Taking acetaminophen was also linked to an increased chance of
eczema and rhinoconjunctivitis, or allergic nasal congestion, in
Because the study was epidemiological -- meaning researchers
asked teens to report after-the-fact how often they took
acetaminophen -- researchers said they can't prove that
acetaminophen helps cause asthma.
But the study is one of several in recent years that has linked
acetaminophen usage during pregnancy or childhood to an increased
risk of developing asthma.
"We cannot assume causation, but the association was found in widely different communities, with widely different patterns of illness and lifestyles," said study author Dr. Richard Beasley, a professor of medicine at the Medical Research Institute of New Zealand. "When you put it together with all of the other studies, clearly there is [cause for concern]."
Nearly 323,000 children between the ages of 13 and 14 who were
participating in the International Study of Asthma and Allergies in
Childhood answered questionnaires about their use of acetaminophen
and history of wheezing, nasal congestion and recurrent, itchy
"Medium" users of acetaminophen were those who had taken the drug at least once during the prior year; "high" users were those who reported taking acetaminophen at least once a month for the past year.
The risk of having asthma was nearly 2.5 times higher among
frequent users, and 43 percent higher among medium users than those
who never took acetaminophen.
Frequent users of acetaminophen were also more than twice as
likely to have rhinoconjunctivitis as kids who never too the drug,
while medium users had a 38 percent greater risk. For eczema,
frequent users had a 99 percent increased risk, while medium users
had a 31 percent increased risk.
The study also found an association with frequency of use and
severity of asthma symptoms. Frequent users of acetaminophen were
2.75 times as likely to say their wheezing was so bad it disturbed
their sleep and limited their ability to speak, Beasley said.
The study will be published Aug. 13 on the American Thoracic
Society's Web site and will later appear in the
American Journal of Respiratory and Critical Care
Marc Boston, a spokesman for McNeil Consumer HealthCare, which
makes Tylenol, said in a statement that "there are no prospective,
randomized controlled studies that show a causal link between
acetaminophen and asthma."
He also noted that "the authors of this [new] study also
published data in the September 2008 edition of
The Lancet. In the press release that accompanied that data, they stated that, 'international asthma guidelines recommend that for both children and adults with asthma, [acetaminophen] is the preferred drug to relieve pain or fever.'"
A second study in the
American Journal of Respiratory and Critical Care Medicine, conducted among children in Ethiopia, also found a link between acetaminophen use and asthma, but not eczema.
Researchers followed some 1,065 women during pregnancy and for
three years after their child was born. Between ages 1 and 3, about
7.7 percent of children had experienced wheezing.
Children who had taken one to three tablets of acetaminophen in
the past month were 88 percent more likely to have asthma, while
children who had taken four tablets were more than seven times more
likely to have asthma.
"These two studies further contribute to what appears to be mounting evidence of an association between acetaminophen and asthma and potentially other allergic diseases," said Matthew Perzanowski, an associate professor of environmental health sciences at Columbia University's Mailman School of Public Health.
So what should parents do?
Experts said a link between ibuprofen, another over-the-counter
pain and fever reducer, and asthma has not been reported. Yet
experts continue to recommend acetaminophen for asthmatic children,
Beasley said, because in some asthmatics, ibuprofen may bring on or
worsen asthma symptoms.
"Acetaminophen is still the preferred drug for children to take who have asthma. Its safety profile is better than ibuprofen, and our findings don't change that," Beasley said.
Yet limiting the use of acetaminophen is probably a wise idea,
said Dr. Andy Nish, an allergist at the Allergy and Asthma Care
Center in Gainesville, Ga.
"My personal opinion is it would be reasonable, particularly in families that had the tendency toward allergic diseases such as asthma, hay fever and eczema, to use acetaminophen judiciously, and perhaps consider the use of an alternative," Nish said.
Young children should not be given aspirin, he noted.
Researchers believe acetaminophen may impact the development of
asthma by altering the body's immune response. Previous studies
have suggested that acetaminophen may lower levels of glutathione
in the lungs, which is involved in detoxifying the body,
Perzanowski said. Other research has found that children with
asthma have lower levels of glutathione in the lungs than those
Asthma rates have been climbing in developed nations over the
last 30 years, leading researchers to wonder what about the modern
Western world could be contributing. Previous research found using
acetaminophen during the first year of life increased the chances
of having asthma at age 6 or 7.
Beasley, Perzanowski and other experts said the next step is
conducting a randomized, controlled trial -- the gold standard of
medical studies -- to see if acetaminophen really is the cause.
But there remain other possible explanations for the
asthma-acetaminophen link. Children who have asthma or who will go
on to receive an asthma diagnosis may develop more colds and
respiratory illnesses, or may seem to have worse colds, than other
kids, Perzanowski said. Colds can cause fever, which may prompt
parents to give acetaminophen.
Frequency of acetaminophen use varied among countries, with only
2 percent of children in Taiwan taking it more than once a month,
while 68 percent of kids in Nigeria did.
U.S. Centers for
Disease Control and Prevention has more on asthma.
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