AllergyIntoleranceCategory

This code system http://hl7.org/fhir/allergy-intolerance-category defines the following codes:

Lvl	Code	Display	Definition
1	food	Food	Any substance consumed to provide nutritional support for the body.
1	medication	Medication	Substances administered to achieve a physiological effect.
2	biologic	Biologic	A preparation that is synthesized from living organisms or their products, especially a human or animal protein, such as a hormone or antitoxin, that is used as a diagnostic, preventive, or therapeutic agent. Also called biological drug. Examples of biologic medications include: vaccines; allergenic extracts, which are used for both diagnosis and treatment (for example, allergy shots); gene therapies; cellular therapies. There are other biologic products, such as tissues, that are not typically associated with allergies.
1	environment	Environment	Any substances that are encountered in the environment, including any substance not already classified as food, medication, or biologic.