ICD-10-CM 2027
ICD-10 code for pertussis
Whooping cough, unspecified species without pneumonia
From the official ICD-10-CM alphabetic index entry “Pertussis”. Page updated September 29, 2026.
About coding pertussis
The ICD-10-CM code for pertussis is A37.90 (Whooping cough, unspecified species without pneumonia).
Within A37.9, choose A37.90 (without pneumonia) only when documentation doesn't support a more specific option: with pneumonia (A37.91).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 202 (Bronchitis and Asthma with CC/MCC, relative weight 0.9474) and DRG 203 (Bronchitis and Asthma without CC/MCC, relative weight 0.6512), in MDC 04 (Diseases and Disorders of the Respiratory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about pertussis ICD-10 codes
What is the ICD-10 code for pertussis?
- A37.90 — Whooping cough, unspecified species without pneumonia.
Is A37.90 billable?
- Yes. A37.90 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can A37.90 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict A37.90 as a principal diagnosis.
Is A37.90 a CC or MCC?
- A37.90 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.