Parents who suck on their child’s pacifier to clean it may also be reducing their child’s risk for allergies, recent study findings suggest.

At 18 months, children who’s parents reported this behavior were less likely than those whose parents cleaned the pacifier in other ways to have asthma (odds ratio=0.12; 95% CI: 0.01 to 0.99) and eczema (OR=0.37; 95% CI: 0.15 to 0.91), Bill Hesselmar, MD, PhD, of Queen Silvia Children’s Hospital in Gothenburg, Sweden, and colleagues reported in Pediatrics.

At 36 months, this association remained for eczema (HR 0.51, 95% CI 0.26 to 0.98) but not asthma, the researchers found.

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“Exposure of the infant to parental saliva might accelerate development of a complex oral/pharyngeal microbiota that, similar to a complex gut microbiota, might beneficially affect tolerogenic handling of antigens by the oral/pharyngeal lymphoid tissues,” Hesselmar and colleagues wrote.

Findings from previous studies have suggested an infant’s microbiota may influence the development of allergic disorders. To further examine this association, the researchers studied whether exposure coming from saliva transferred on a pacifier was related to allergy development among 184 full-term infants born to women enrolled in the AllergyFlora study.

Parents were interviewed about pacifier use, cleaning practices and other information, when infants were aged 6 months. Overall, 75% used a pacifier in the first 6 months of life.

Among infants who used pacifiers, 83% of parents reported using tap water to clean the pacifiers, 54% reported boiling and 48% reported using their mouths.

At 18 months, 25% of the children had eczema, 5% had asthma, 15% had sensitization to food antigens and 2% had sensitization to inhaled antigens.

Although pacifier use was not in and of itself related to any of these outcomes, children of parents who used their mouths for pacifier cleaning had a lower likelihood of developing eczema or asthma. Sensitization to neither food nor inhaled allergens was associated with pacifier use.

Infants who were born vaginally and whose parents reported pacifier sucking had the lowest prevalence of eczema, whereas those with neither characteristic had the highest prevalence, the researchers found.

“Thus, vaginal delivery, which is a source for transfer of a complex microbiota from mother to infant and parent and infant sharing of a pacifier might both lead to microbial stimulation, with beneficial effects on allergy development,” they wrote.

The researchers found no differences in respiratory infection rates among children of parents who sucked on pacifiers vs. children of parents who did not.

Study limitations included small sample size and the difficulty of diagnosing asthma in early childhood. Further, larger studies are needed to replicate the findings in older children.


  1. Hesselmar B et al. Pediatrics. 2013; doi:10.1542/peds.2012-3345.