This entry is an adaptation of the IHE Allergies And Intolerances Entry and IHE Problem Entry (IHE PCC).

Note: including the templateId '1.3.6.1.4.1.19376.1.5.3.1.4.5' requires that also the template ID '2.16.840.1.113883.10.20.1.28' is included.

The <code> element represents the kind of allergy observation made, to a drug, food or environmental agent, and whether it is an allergy, non-allergy intolerance, or unknown class of intolerance (not known to be allergy or intolerance). The <code> element of an allergy entry shall be provided, and a code and codeSystem attribute shall be present.

The value element shall be present in a coded or uncoded form. In both cases the type shall be set to xsi:type='CD'.
In the case of no information or known absence of allergies, one of the following codes from the eHDSIAbsentOrUnknownAllergy value set has to be used:

If one of these values is used, the participant used for indicating the allergy agent shall be omitted.
In all other cases it shall be in its uncoded form and may contain a <reference> to the <originalText> in the narrative where the allergy is described.

The substance that causes the allergy or intolerance should be specified in the <participant> structure.
This is the preferred way an allergy is supposed to be expressed.
However it is recognized that in some contexts a controlled vocabulary is used for describing the allergy to a substance; or for asserting known absence or unavailability of information.
In this case the <participant> structure shall be omitted.
The agent responsible for an allergy or adverse reaction is not always a manufactured material (for example, food allergies), nor is it necessarily consumed. The following constraints reflect limitations in the base CDA R2 specification, and should be used to represent any type of responsible agent, i.e., use playingEntity classCode = "MMAT" for all agents, manufactured or not.

An allergy entry can record the reactions that are manifestations of the allergy or intolerance as shown below. It uses a related entry (<entryRelationship>) that indicates the manifestations (typeCode='MFST') the reported allergy or intolerance. These are events that may occur, or have occurred in the past as a reaction to the allergy or intolerance<entryRelationship typeCode='MFST'>

The entry contained with this entry relationship is some sort of problem that is a manifestation of the allergy. It is recorded using the Problem Entry structure.

An optional <entryRelationship> element may be present indicating the severity of the problem. If present, this <entryRelationship> element shall contain a severity observation conforming to the Severity entry template (1.3.6.1.4.1.19376.1.5.3.1.4.1).

The related statement is made about the severity of the condition, concern, or allergy). This observation is recorded inside an <entryRelationship> element occurring in the containing entry. The containing <entry> is the subject (typeCode='SUBJ') of this new observation, which is the inverse of the normal containment structure, thus inversionInd='true'.

The related statement is another event (moodCode='EVN') observing (<observation classCode='OBS'>) the severity of the (surrounding) related entry (e.g., a condition or allergy).