ICD-10-CM 2027
ICD-10 code for Fulvestrant Faslodex long-term drug therapy
Long term (current) use of other agents affecting estrogen receptors and estrogen levels
From the official ICD-10-CM alphabetic index entry “Long-term (current) (prophylactic) drug therapy (use of) › fulvestrant (Faslodex)”. Page updated September 29, 2026.
About coding Fulvestrant Faslodex long-term drug therapy
The ICD-10-CM code for Fulvestrant Faslodex long-term drug therapy is Z79.818 (Long term (current) use of other agents affecting estrogen receptors and estrogen levels).
Within Z79.81, choose Z79.818 (other agents affecting estrogen receptors and estrogen levels) only when documentation doesn't support a more specific option: selective estrogen receptor modulators (SERMs) (Z79.810) and aromatase inhibitors (Z79.811).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 951 (Other Factors Influencing Health Status, relative weight 0.5577), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), 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 Fulvestrant Faslodex long-term drug therapy ICD-10 codes
What is the ICD-10 code for Fulvestrant Faslodex long-term drug therapy?
- Z79.818 — Long term (current) use of other agents affecting estrogen receptors and estrogen levels.
Is Z79.818 billable?
- Yes. Z79.818 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Z79.818 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is Z79.818 a CC or MCC?
- No. Z79.818 is neither a CC nor an MCC under MS-DRG v44.0.