Pneumonia is classified under ICD-10-CM code J18, which requires specifying the type. Common billable codes include J18.0 (bronchopneumonia), J18.1 (lobar pneumonia), J18.8 (other pneumonia), and J18.9 (unspecified organism).
Primary codes
Billable
Billable
Extension
—
7th character
—
POA exempt
No
Coding risks
- Assigning when documentation supports a more specific code
Hierarchy
Code comparison
Compare key differences between related codes to select the most specific option.
| Code | Description | Scenario |
|---|---|---|
| J18.9 | Pneumonia, unspecified organism | Pneumonia documented without organism, anatomic pattern, or lobar involvement specified. |
| J18.0 | Bronchopneumonia, unspecified organism | Bronchopneumonia documented with patchy bronchial involvement, causative organism not identified. |
| J18.1 | Lobar pneumonia, unspecified organism | Lobar pneumonia documented on imaging with lobe involvement, organism not identified. |
| J18.8 | Other pneumonia, unspecified organism | Pneumonia documented with distinguishing features that do not fit bronchopneumonia, lobar, or unspecified categories. |
Select the most specific code supported by the encounter documentation. More specific codes improve reimbursement accuracy and reduce audit risk.
Code ranges
Pneumonia, unspecified organism
Pneumonia coded when the causal organism is not identified or documented, spanning bronchopneumonia, lobar, hypostatic, and unspecified forms.
Influenza and pneumonia
Acute lower respiratory infections including seasonal and novel influenza and pneumonias classified by specific organism or unspecified etiology.
Viral pneumonia, not elsewhere classified
Pneumonia caused by identified viral agents such as adenovirus, RSV, parainfluenza, metapneumovirus, and SARS-associated coronaviruses.
Bacterial pneumonia, not elsewhere classified
Pneumonia caused by identified bacterial organisms including Klebsiella, Pseudomonas, staphylococcal, streptococcal, and Mycoplasma species.
Pneumonitis due to solids and liquids
Lung inflammation from aspiration of food, vomit, oils, or other substances, classified separately from infectious pneumonia.
Coding risks
Avoid these common coding issues when reporting Pneumonia.
Impact
Assigning J18.9 without a documented organism may miscode when culture data supports a specific organism code such as J15.9.
Mitigation
Consider querying the provider when sputum cultures, PCR, or imaging suggest a specific organism before defaulting to J18.
Related codes
Ancillary and co-coding
Codes commonly reported with the primary diagnosis on the same claim.
Z-code variants
Family history, personal history, or screening encounter codes related to this condition.
In pregnancy
Pregnancy-specific O-code adaptations used in place of the primary when the condition occurs during or complicates pregnancy.
Differential codes
Alternative or commonly confused codes to consider when documentation suggests a different condition than the primary diagnosis.
Frequently asked questions
Use J18.9 only when the chart documents pneumonia without organism or anatomic pattern. More specific codes take precedence whenever documented.
References
Compiled from the following authoritative coding references. Last updated 2026-08-04.