<AllergyIntolerance xmlns="http://hl7.org/fhir">
    <id value="PatientAllergy Instance Example" />
    <meta>
        <profile value="http://hl7.org/fhir/us/bser/StructureDefinition/PatientAllergy" />
    </meta>
    <verificationStatus value="confirmed" />
    <type value="allergy" />
    <patient>
        <reference value="PatientRole/InstanceExample" />
    </patient>
    <onsetAge>
        <value value="20" />
        <unit value="yrs" />
        <system value="http://unitsofmeasure.org" />
        <code value="yrs" />
    </onsetAge>
    <reaction>
        <substance>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="3718001" />
                <display value="Cow&#39;s milk" />
            </coding>
        </substance>
        <manifestation>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="422400008" />
                <display value="Vomiting" />
            </coding>
        </manifestation>
        <severity value="mild" />
    </reaction>
</AllergyIntolerance>