2026 ICD-10-CM Diagnosis Code T45.1X5AAdverse effect of antineoplastic and immunosuppressive drugs, initial encounter
T45.1X5A is a billable ICD-10-CM diagnosis code for adverse effect of antineoplastic and immunosuppressive drugs, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for T45.1X5A.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accelerated rheumatoid nodulosis
- Accelerated rheumatoid nodulosis caused by methotrexate
- Aclarubicin adverse reaction
- Acquired pancytopenia
- Acral erythema due to cytotoxic therapy
- Acute promyelocytic leukemia, FAB M3
- Adverse reaction to antineoplastic antibiotics
- Adverse reaction to dimethyl sulfoxide and/or idoxuridine
- Adverse reaction to rituximab administered by infusion
- Adverse reaction to sarilumab
- Adverse reaction to trastuzumab administered by infusion
- Adverse reaction to triazene
- Agranulocytosis
- Agranulocytosis due to and following administration of antineoplastic agent
- Aldesleukin adverse reaction
- Alkylating drug adverse reaction
- Amifostine adverse reaction
- Amsacrine adverse reaction
- Anemia caused by antineoplastic agent
- Antimetabolite adverse reaction
- Antineoplastic adverse reaction
- Aplastic anemia caused by antineoplastic agent
- Aplastic anemia due to drugs
- Azathioprine adverse reaction
- Azoospermia caused by chemotherapy
- Bleomycin adverse reaction
- Busulfan adverse reaction
- Carboplatin adverse reaction
- Cardiomyopathy caused by drug
- Carmustine adverse reaction
- Cellular atypia caused by antineoplastic agent
- Chlorambucil adverse reaction
- Chlormethine adverse reaction
- Chronic cyclosporin A nephrotoxicity
- Chronic drug-induced renal disease
- Chronic painful polyneuropathy
- Chronic painful polyneuropathy following chemotherapy
- Chronic peripheral neuropathic pain
- Cirrhosis of liver caused by methotrexate
- Cisplatin adverse reaction
- Complication of chemotherapy
- Crisantaspase adverse reaction
- Cyclophosphamide adverse reaction
- Cyclosporin adverse reaction
- Cytarabine adverse reaction
- Cytotoxic antibiotic adverse reaction
- Dacarbazine adverse reaction
- Dactinomycin adverse reaction
- Dermatosis caused by immunosuppressant
- Dermatosis due to cytotoxic therapy
- Differentiation syndrome due to and following chemotherapy co-occurrent with acute promyelocytic leukemia
- Dilated cardiomyopathy caused by anthracycline
- Dilated cardiomyopathy caused by drug
- Dimethyl sulfoxide adverse reaction
- Disorder of kidney caused by cisplatin
- Disorder of skin caused by epidermal growth factor receptor inhibitor
- Doxorubicin adverse reaction
- Drug-induced cirrhosis of liver
- Drug-induced immunodeficiency
- Drug-induced tubulointerstitial nephritis
- Epirubicin adverse reaction
- Esophagitis due to chemotherapy
- Estramustine adverse reaction
- Ethoglucid adverse reaction
- Etoposide adverse reaction
- Fatigue due to chemotherapy
- Fludarabine adverse reaction
- Fluorouracil adverse reaction
- Gonad regulating hormone adverse reaction
- Goserelin adverse reaction
- Growing teratoma syndrome
- Heart failure following administration of antineoplastic agent
- Hematologic complication of procedure
- Hydroxycarbamide adverse reaction
- Iatrogenic immunodeficiency-associated lymphoproliferative disorder
- Idarubicin adverse reaction
- Ifosfamide adverse reaction
- Immunodeficiency caused by long term therapeutic use of drug
- Immunodeficiency caused by long term therapeutic use of immunosuppressant
- Immunodeficiency secondary to chemotherapy
- Immunosuppressant adverse reaction
- Inflammation of mucous membrane due to and following chemotherapy
- Leuprorelin adverse reaction
- Lomustine adverse reaction
- Lymphoproliferative disorder caused by methotrexate
- Malignant neoplasm after immunosuppressive therapy
- Melphalan adverse reaction
- Mercaptopurine adverse reaction
- Methotrexate adverse reaction
- Methotrexate poisoning
- Methotrexate skin ulceration
- Methyl CCNU nephropathy
- Mitobronitol adverse reaction
- Mitomycin adverse reaction
- Mitoxantrone adverse reaction
- Myelopathy post intrathecal injection of chemotherapeutic agent
- Myelosuppression
- Myelosuppression due to chemotherapy
- Nephritis caused by drug
- Nephropathy induced by cyclosporine
- Nephropathy induced by tacrolimus
- Neurological pain disorder
- Neurotoxicity caused by L-asparaginase
- Neurotoxicity caused by methotrexate
- Neurotoxicity caused by procarbazine
- Neurotoxicity caused by vinblastine
- Neurotoxicity caused by vincristine
- Nitrogen mustard derivative adverse reaction
- Nitrosurea adverse reaction
- Paclitaxel adverse reaction
- Palmar erythema
- Pancytopenia caused by immunosuppressant
- Pancytopenia caused by medication
- Pentostatin adverse reaction
- Peripheral neuropathic pain
- Peripheral neuropathy due to and following antineoplastic therapy
- Plicamycin adverse reaction
- Poisoning by L-asparaginase
- Post-immunosuppression viral warts
- Procarbazine adverse reaction
- Procarbazine poisoning
- Razoxane adverse reaction
- Retinoid adverse reaction
- Ruxolitinib withdrawal
- Secondary aplastic anemia
- Stomatitis due to cytotoxic therapy
- Stomatitis medicamentosa
- Terpenes adverse reaction
- Therapy related acute myeloid leukemia due to and following administration of antineoplastic agent
- Therapy-related myelodysplastic syndrome
- Thioguanine adverse reaction
- Thiotepa adverse reaction
- Thrombophilia due to antineoplastic agent therapy
- Toxic cardiomyopathy
- Toxic dilated cardiomyopathy
- Treosulfan adverse reaction
- Triptorelin adverse reaction
- Ulcerative inflammation of oral mucous membrane due to and following administration of antineoplastic agent
- Ulcerative stomatitis
- Vinblastine adverse reaction
- Vinblastine poisoning
- Vinca alkaloid adverse reaction
- Vincristine adverse reaction
- Vincristine poisoning
- Vindesine adverse reaction
- Warts in immune-deficient state
Coding GuidelinesGuidance
When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified (T45). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Agranulocytosis
a decrease in the number of granulocytes; (basophils; eosinophils; and neutrophils).Feline Panleukopenia
a highly contagious dna virus infection of the cat family, characterized by fever, enteritis and bone marrow changes. it is also called feline ataxia, feline agranulocytosis, feline infectious enteritis, cat fever, cat plague, and show fever. it is caused by feline panleukopenia virus or the closely related mink enteritis virus or canine parvovirus.Agranulocytosis
a marked decrease in the number of mature granulocytes (most often neutrophils) in the peripheral blood.Chemotherapy Related Agranulocytosis|Chemotherapy-Related Agranulocytosis
agranulocytosis that occurs with chemotherapy.Congenital Neutropenia|congenital neutropenia|genetic infantile agranulocytosis|infantile genetic agranulocytosis
a rare congenital disorder characterized by mild or severe reduction of neutrophils in the peripheral blood and recurrent infantile infections.Cyclic Neutropenia|CH|CN|Cyclic Agranulocytosis|Cyclic Hematopoiesis|Cyclic Hematopoiesis|Dysplasia, Myelocytic Periodic|Periodic Neutropenia|cyclic neutropenia|periodic neutropenia
a hematologic disorder caused by a mutation in the elane (ela2) gene; clinical manifestations include recurrent neutropenia with resultant susceptibility to infection leading to fever.Tumor Protein 63|CUSP|Chronic Ulcerative Stomatitis Protein|Keratinocyte Transcription Factor KET|TP63|Transformation-Related Protein 63|Tumor Protein p73-Like|p40|p51|p63|p73L
tumor protein 63 (680 aa, ~77 kda) is encoded by the human tp63 gene. this protein plays a role in the mediation of both transcription and limb morphogenesis.Ulcerative Stomatitis
inflammation of the mouth mucosa associated with the presence of ulcers.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
Patient EducationClinical
Drug Reactions
Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.
The full article covers:
- What is a drug interaction?
- What are side effects?
- What are drug allergies?
- How can I stay safe when taking medicines?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T45.1X5A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T45.1X5AOverview
Is T45.1X5A (Adverse effect of antineoplastic and immunosuppressive drugs) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of antineoplastic and immunosuppressive drugs, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T45.1X5A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of antineoplastic and immunosuppressive drugs, such as an emergency visit or first evaluation.
What MS-DRG does T45.1X5A group to?
On inpatient claims, adverse effect of antineoplastic and immunosuppressive drugs, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T45.1X5A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of antineoplastic and immunosuppressive drugs, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
What is the ICD-9 equivalent of T45.1X5A?
Under the General Equivalence Mappings, adverse effect of antineoplastic and immunosuppressive drugs, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E933.1 (adv eff antineoplastic). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
