Diarrhea is a common condition characterized by loose and watery stools during bowel motions that are more frequent than normal. Diarrhea is often a temporary discomfort, but if not treated appropriately and on time, it can lead to major health problems. And when we talk about the field of medical billing and coding then there are some specific ICD-10 codes for diarrhea. Accurate coding requires knowledge of all diarrhea ICD-10 codes for medical billers. So let’s talk about all of the ICD-10 codes for diarrhea and see how this system operates and why these codes are crucial for medical professionals.
Quick Answer:
R19.7 (Diarrhea, unspecified) is the ICD-10-CM code used when a patient has diarrhea, but the medical record does not identify the exact cause. It is included in Chapter 18: Symptoms, Signs, and Abnormal Clinical Findings and is valid for the FY2026 code set (October 1, 2025, through September 30, 2026). Use R19.7 only when there isn’t enough documentation to assign a more specific code, such as for infectious diarrhea (A09), noninfective gastroenteritis and colitis (K52.9), functional diarrhea (K59.1), or IBS with diarrhea (K58.0).
What is Diarrhea?
Most individuals are familiar with diarrhea since they have all had it at some time in their lives. Diarrhea occurs when the bowel moves unusually and is characterized by frequent, loose, and watery stools. Diarrhea can be caused by different factors, including infections, dietary choices, and underlying medical disorders. Most people treat this condition on their own but remember that if you do not treat this disease then it can lead to dehydration and other complications. So, when it gets more severe then it is important to properly diagnose and treat it.
Common Causes of Diarrhea
- Parasitic, bacterial, or viral infections can cause acute diarrhea.
- Food allergies like gluten allergies and celiac disease
- A reaction to medications like antibiotics can disturb the balance of intestinal flora and produce diarrhea.
- Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) can cause persistent diarrhea.
Symptoms of Diarrhea
The symptoms of diarrhea can be different but common signs include:
- The most common symptom of diarrhea is loose bowel motions. This issue can cause dehydration in more severe cases.
- Many people who have diarrhea get stomach cramps or pain.
- Dehydration is a serious consequence of diarrhea that causes symptoms such as dizziness, dry mouth, and dark urine.
What is ICD-10?
When a patient visits the doctor and is diagnosed with a disease, the billing process starts, in which each service that the patient gets is documented. And to categorize each disease, different ICD-10 codes are utilized.
ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification) is the diagnosis coding system every HIPAA-covered provider in the United States has used since October 1, 2015. It is designed by WHO to classify the symptoms and their causes and ensures consistency in diagnosing and coding various medical conditions. It’s maintained jointly by the Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics (NCHS), with updates released every October 1. Currently, they have the 10th Edition, and very soon the 11th edition is expected. They have defined a standardized way of documenting patient diagnoses and conditions. This way all the medical records ensure clarity and consistency.
The Importance of Accurate Coding
Accurate coding is an important part of the healthcare sector because it allows healthcare providers to get timely payment for their services. Additionally, it helps in monitoring the frequency of different illnesses and diseases, which is beneficial for the study of public health. By accurately recording a patient’s medical information, accurate coding enhances patient care. ICD-10 data is also used by several health organizations and governments for resource allocation and healthcare planning. ICD-10 code for diarrhea is one of these codes that medical billing companies need to document diarrhea conditions.
ICD-10 Code for Diarrhea
ICD-10 specifically codes diarrhea as R19.7 especially during the patient’s first visit when the cause of diarrhea is still unknown. This number is used in claims or medical records to indicate the presence of diarrhea without any lab results, imaging tests, or a confirmed diagnosis yet to identify the underlying cause. It is used to treat frequent, loose, or watery stools.
When to Use R19.7
Use R19.7 in these situations:
- The patient is seen for the first time with acute diarrhea and no infectious cause has been documented yet.
- Diarrhea is recorded as a symptom while stool tests or other evaluations are still in progress.
- The cause of the diarrhea cannot be identified, even after a reasonable medical evaluation.
Subtypes of diarrhea
Nausea with vomiting, unspecified (R11.2): Used when a patient has both diarrhea and vomiting, but the underlying cause has not yet been diagnosed.
Noninfective gastroenteritis and colitis, unspecified (K52.9): Used to treat any type of non-infectious diarrhea brought on by food intolerances, diseases like IBS, or other non-infectious causes.
Acute diarrhea (K52.0): Usually short-term and caused by illness, food poisoning, or dietary changes.
Chronic diarrhea (K52.2): Used for long-lasting diarrhea, often related to an underlying medical condition.
Chronic diarrhea in children (K52.81): Used for eosinophilic gastritis or gastroenteritis that is not classified elsewhere.
Traveler’s diarrhea (K52.1): Used for diarrhea that develops during or after travel, usually due to exposure to unfamiliar germs.
Inflammatory diarrhea (K52.3): Used when diarrhea is linked to inflammation in the digestive tract, such as in Crohn’s disease or ulcerative colitis.
Coding Rule to Remember
R19.7 means nothing has been investigated yet. K59.1 means an investigation happened and came back negative for a structural or infectious cause. They are never interchangeable, and they can never be billed together on the same claim.
Specific ICD-10 Codes for Infectious Diarrhea
A00 - Cholera
- A00.0 – Cholera that happens due to Vibrio cholerae 01 and biovar cholerae
- A00.1 – Cholera that happens due to Vibrio cholerae 01 and biovar eltor
- A00.9 – Cholera, unspecified
A01 - Typhoid and Paratyphoid Fevers
- A01.0- Typhoid fever (bill to the 6th-character subcode: A01.00 unspecified, A01.01 meningitis, A01.02 with heart involvement, A01.03 pneumonia, A01.04 arthritis, A01.05 osteomyelitis, or A01.09 other complications)
- A01.0 – Typhoid Fever
- A01.1 – Paratyphoid Fever A
- A01.2 – Paratyphoid Fever B
- A01.3 – Paratyphoid Fever C
- A01.4 – Paratyphoid Fever, Unspecified
A02 - Other Salmonella Infections
- A02.0 – Salmonella enteritis
- A02.1 – Salmonella sepsis
- A02.2- Localized salmonella infections (bill to a 5th-character subcode like A02.20 unspecified, A02.21 meningitis, A02.22 pneumonia, A02.23 arthritis, A02.24 osteomyelitis, A02.25 pyelonephritis, or A02.29 other localized infection)
- A02.8 – Other specified salmonella infections
- A02.9 – Salmonella infection, unspecified
A03 - Shigellosis
- A03.0 – Shigellosis due to Shigella dysenteriae
- A03.1 – Shigellosis due to Shigella flexneri
- A03.2 – Shigellosis due to Shigella boydii
- A03.3 – Shigellosis due to Shigella sonnei
- A03.8 – Other Shigellosis
- A03.9 – Shigellosis, unspecified
A04 - Other Bacterial Intestinal Infections
- A04.0 – Enteropathogenic Escherichia coli infection
- A04.1 – Enterotoxigenic Escherichia coli infection
- A04.2 – Enteroinvasive Escherichia coli infection
- A04.3 – Enterohemorrhagic Escherichia coli infection
- A04.4 – Other intestinal Escherichia coli infections
- A04.5 – Campylobacter enteritis
- A04.6 – Enteritis due to Yersinia enterocolitica
- A04.7- Enterocolitis due to Clostridium difficile (non-billable parent, always resolve to A04.71 recurrent, or A04.72 not specified as recurrent)
- A04.8 – Other specified bacterial intestinal infections
- A04.9 – Bacterial intestinal infection, unspecified
A05 - Bacterial Foodborne Intoxications Not Elsewhere Classified
- A05.0 – Foodborne Staphylococcal intoxication
- A05.1 – Foodborne botulism (note: non-foodborne botulism like infant or wound botulism is coded A48.51 or A48.52, not A05.1)
- A05.2 – Foodborne Clostridium perfringens intoxication
- A05.3 – Foodborne Vibrio parahaemolyticus intoxication
- A05.4 – Foodborne Bacillus cereus intoxication
- A05.8 – Other specified bacterial foodborne intoxications
- A05.9 – Bacterial foodborne intoxication, unspecified
Coding Tip:
Codes with a hyphen at the end (such as A01.0-, A02.2-, and A04.7-) are not complete billable codes. You must add the required extra character to make them valid. Using an incomplete category code instead of the full code can lead to claim denials.
Specific ICD-10 Codes for Non-Infectious Diarrhea
K52 - Colitis and Unspecified Noninfective Gastroenteritis and Other
- K52.0 – Gastroenteritis and colitis due to radiation
- K52.1 – Toxic gastroenteritis and colitis
- K52.2 – Allergic and dietetic gastroenteritis and colitis
- K52.8 – Other specified noninfective gastroenteritis and colitis
- K52.9 – Noninfective gastroenteritis and colitis, unspecified
K59 - Other Functional Intestinal Disorders
- K59.0 – Constipation (bill to a subcode such as K59.00 unspecified or K59.01 slow transit constipation)
- K59.1 – Functional diarrhea
- K59.2 – Neurogenic bowel, not elsewhere classified
- K59.3 – Megacolon, not elsewhere classified
- K59.4 – Anal spasm
- K59.8 – Other specified functional intestinal disorders
- K59.9 – Functional intestinal disorder, unspecified
Only K59.1 (Functional diarrhea) is used for diarrhea. The other K59 codes are included for reference because they are in the same category and can be easily selected by mistake from a coding dropdown list.
ICD-10 Codes for Diarrhea in Specific Conditions
R19 - Signs Involving the Digestive System and Abdomen and Other Symptoms
R19.7 – Diarrhea, unspecified
E86 - Volume Depletion
- E86.0 – Dehydration
- E86.1 – Hypovolemia
- E86.9 – Volume depletion, unspecified
ICD-10 and CPT: Matching the Diagnosis with the Procedure
A diarrhea ICD-10 code supports payment only when it matches the medical service (CPT or HCPCS code) billed. Some common examples include:
- Office visits (99202–99215): Most diarrhea diagnosis codes can be used if the medical record supports the level of the visit billed.
- Stool tests: Tests such as stool culture, ova and parasite testing, or C. diff testing are often billed with R19.7 or A09 until the test results confirm the final diagnosis.
- Colonoscopy or endoscopy (45378 and related codes): These procedures usually need a diagnosis showing chronic or ongoing diarrhea like K52.9 or K59.1, instead of an unspecified acute diarrhea code.
- IV hydration (96360–96361): If IV fluids are given because the patient is dehydrated, the claim should also include the dehydration code E86.0, not just the diarrhea diagnosis.
Why Choose M&M Claims Care?
M&M Claims Care is an experienced medical billing company in the USA. If you want accurate billing and documentation services, you need our expert team of medical billers. We help you make each process accurate and compliant so you can give more time to your patients. Your practice deserves nothing but a reliable medical billing partner.
Frequently Ask Questions
The most common code is R19.7 for Diarrhea, unspecified. It is used when the cause of diarrhea is not yet known. If the cause is later confirmed, a more specific ICD-10 code should be used.
Acute diarrhea with no confirmed cause is usually coded as R19.7. If it is caused by an infection, use A09 or a more specific A0x code if the exact germ is identified.
Chronic diarrhea (lasting 4 weeks or longer) is usually coded as K52.9 (Noninfective gastroenteritis and colitis, unspecified) after infection has been ruled out. If tests confirm functional diarrhea, use K59.1 instead.
Traveler’s diarrhea is usually coded as A09 if the exact cause is unknown. If testing identifies the germ, use the appropriate A04.x or A08.x code. The medical record should include the patient’s travel history and when symptoms started.
No. R19.7 is for unspecified diarrhea, while K59.1 is for functional diarrhea, which is a more specific diagnosis. Because of the ICD-10-CM Excludes1 rule, these two codes should not be reported together on the same claim.
