Allergy Status ICD-10-CM codes

Z88 and Z91.0x are status codes for a known allergy that is not reacting today. Z88 covers drugs and biologicals: Z88.0 penicillin, Z88.1 other antibiotics, Z88.2 sulfonamides, Z88.3 other anti-infectives, Z88.4 anesthetic agents, Z88.5 narcotics, Z88.6 analgesics such as NSAIDs, Z88.7 serum and vaccines, Z88.8 other drugs, Z88.9 unspecified drug. Z91.0x covers everything else: Z91.010 peanuts, Z91.011x milk products, Z91.012x eggs, Z91.013 seafood, Z91.014 mammalian meat (alpha-gal), Z91.018 other foods, Z91.02 food additives, Z91.030 bee stings, Z91.038 other insects, Z91.040 latex, Z91.041 radiographic contrast, Z91.048 other nonmedicinal substances.

These are secondary codes and are reported when the allergy is relevant to the encounter: the penicillin allergy that changed the antibiotic choice, the contrast allergy that requires premedication before a CT, the latex allergy on a surgical record. They are not required on every claim for every listed allergy, and a patient-reported intolerance (nausea from codeine) is not an allergy and does not get Z88.5 unless the provider labels it one.

A current allergic reaction is coded to the reaction, not to the status code. Drug rash is L27.0 with the T36 to T50 adverse effect code, anaphylaxis is T78.0x or T88.6x, and an unspecified allergic reaction is T78.40XA; Z88 or Z91.0x may be added to show the allergy is now known, and Z87.892 (personal history of anaphylaxis) is reported on later encounters where prior anaphylaxis matters.

Allergy testing is its own encounter, Z01.82, and immunotherapy injections are Z51.6 (desensitization to allergens) with the allergic condition such as J30.1 first. The milk and egg codes carry sixth-character detail for tolerance of baked forms (Z91.0111, Z91.0121) that allergists use to document oral immunotherapy progress.