2026 ICD-10-CM Diagnosis Code T48.1X5AAdverse effect of skeletal muscle relaxants [neuromuscular blocking agents], initial encounter
T48.1X5A is a billable ICD-10-CM diagnosis code for adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], 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 T48.1X5A.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Adverse reaction to central nervous system muscle-tone depressants
- Adverse reaction to ganglion blocking drug
- Adverse reaction to neuromuscular blocking agent
- Adverse reaction to skeletal muscle relaxants
- Alcuronium adverse reaction
- Atracurium adverse reaction
- Complication due to and following neuromuscular block
- Depolarizing muscle relaxant adverse reaction
- Drug-induced apnea
- Gallamine adverse reaction
- Methocarbamol adverse reaction
- Mivacurium adverse reaction
- Mivacurium apnea
- Muscle paresis due to and following neuromuscular blockade
- Non-depolarizing muscle relaxant adverse reaction
- Pain following administration of agent
- Pancuronium adverse reaction
- Rocuronium adverse reaction
- Suxamethonium adverse reaction
- Suxamethonium apnea
- Suxamethonium pains
- Tubocurarine adverse reaction
- Vecuronium adverse reaction
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 agents primarily acting on smooth and skeletal muscles and the respiratory system (T48). 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
Succinylcholine
a quaternary skeletal muscle relaxant usually used in the form of its bromide, chloride, or iodide. it is a depolarizing relaxant, acting in about 30 seconds and with a duration of effect averaging three to five minutes. succinylcholine is used in surgical, anesthetic, and other procedures in which a brief period of muscle relaxation is called for.Vecuronium Bromide
monoquaternary homolog of pancuronium. a non-depolarizing neuromuscular blocking agent with shorter duration of action than pancuronium. its lack of significant cardiovascular effects and lack of dependence on good kidney function for elimination as well as its short duration of action and easy reversibility provide advantages over, or alternatives to, other established neuromuscular blocking agents.
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 T48.1X5A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T48.1X5AOverview
Is T48.1X5A a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T48.1X5A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], such as an emergency visit or first evaluation.
What MS-DRG does T48.1X5A group to?
On inpatient claims, adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], 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 T48.1X5A be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], 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 T48.1X5A?
Under the General Equivalence Mappings, adverse effect of skeletal muscle relaxants [neuromuscular blocking agents], initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E945.2 (adv eff skelet musc relx). 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.
