Sample adults were also asked whether a doctor or other health professional had ever diagnosed them as having an allergic reaction to medication severe enough to require treatment or medication (MALLERGYEV) and, if so, if they had such a medically-diagnosed reaction to medication during the past 12 months (MALLERGYR). In addition, HAYFEVERYR identifies sample adults who had been told by a doctor or other health professional that they had hay fever during the past 12 months.

Information on food allergies was also collected for sample children. For children, however, the interviewer simply asked whether the child had "any kind of food or digestive allergy" during the past 12 months, without requiring that the allergy be diagnosed by a doctor or other health professional (FALLERGYR).

For sample children in 1997 forward, information was also collected on whether the following types of allergies were present during the past 12 months:

• Hay fever (HAYFEVERYR)

• Respiratory allergies (RALLERGYR)

• Skin allergies (SALLERGYR)

In 2007 only, interviewers asked respondents if the sample child had any other allergies besides hay fever or respiratory, food, or skin allergies during the past 12 months (OTHALLERGYR).