How to Lookup ICD-10 Codes

Looking up ICD-10 codes can help you understand your medical bills. You may need to look up an ICD-10 code if you're trying to sort out a medical pre-approval or billing issue with your health insurance provider.

The International Classification of Diseases, Tenth Revision (ICD-10) is used by healthcare providers to classify and code every disease, symptom, and injury to submit insurance claims or prior authorizations. The ICD-10 can often be found on patient reports or bills, but sometimes you have to look it up yourself.

There are more than 70,000 ICD-10 codes, each with specific definitions. This can make it challenging to look them up and find the right code. If the code is incorrect, the coverage or approval of a test or treatment may be denied.

ICD-10 Code Lookup

Look for the specific ICD-10 code on your medical records. If you can't find it, there are several other places you can search, including governmental online search engines and commercial apps.

Medical Records

You can often find the ICD-10 code printed after or under the "Diagnosis" (or "Dx") heading on a medical report, bill, or provider letter. Explanation of benefits (EOB) statements from your insurer might also contain ICD codes. It can contain up to seven characters, starting with a capital letter.

Unfortunately, not every provider includes ICD-10 codes on a medical report. If this is the case, you may need to look it up yourself.

NCHS ICD-1O Code Browser

Offered by the National Center for Health Statistics (NCHS), this free ICD-10 lookup tool can provide you with an ICD-10 code when you input a diagnosis (such as "skin allergy") into the "Enter Search Terms" field.

You can then click on the ICD-10 category on the results page (like "dermatitis and eczema") to find the exact ICD-10 code for the condition you experienced (such as "allergic contact dermatitis due to metals").

The NCHS tool also allows you to input an ICD-10 code in the "Find Code in Tabular" field to check if the code submitted by your healthcare provider is the correct one.

CMS ICD-10 Code Lookup Tool

Offered by the Centers for Medicare and Medicaid Service (CMS), this online tool allows you to input a diagnosis in the "Start Your Search" field and select the procedure you had on the search results page (such as "allergy skin testing").

After you click on the link, you can scroll down the document to the "ICM-10-CM Codes That Support Medical Necessity" heading to find the relevant ICD-10 code for your condition.

You can also check if the test is not covered under "ICM-10-CM Codes That Do Not Support Medical Necessity." This may help you understand why a claim was denied.

ICD10Data.com

ICD10Data.com is a free commercial website that allows you to click on a list of 22 medical categories (like "diseases of the skin") and continue clicking from subcategory (like "dermatitis and eczema") to sub-subcategory (like "allergic contact dermatitis") and sub-sub-subcategory (like "allergic contact dermatitis due to metals") until you get the exact ICD-10 code you need.

Are You Using the Right Revision?

The ICD receives annual updates, which can sometimes affect coding. In 2023, for example, 34 new codes were added.

This is why you need to be sure that the code included in a medical report is from the current revision. If not, you may experience problems with billing or claims.

Why You May Need to Look Up a Code

You may need to look up an ICD code because:

• Your insurance claim is being disputed.
• Your insurance claim has not been paid.
• You have submitted for pre-approval for a certain treatment or specialist visit and were denied.
• You believe there is a billing error on your account.

In some cases, the claim will have been denied simply because the code was incorrect. At other times, a dispute may arise when the ICD-10 code (which classifies diagnosis) does not align with the CPT code (which classifies procedures) or HCPSC code (which classifies drugs, supplies, and other procedures not included in the CPT).

If this happens, finding the ICD-10 code can help you determine where the problem arose and what you can do to fix it.

What Codes Mean

ICD-10 codes consist of up to seven characters that classify medical diagnoses in a specific way:

• The first three characters—a letter and two numbers—classify the disease or health condition.
• After the first three characters is a period.
• The next three numbers describe the cause of the disease, how severe it is, or where in the body it is located (including whether it is on the left side, right side, or both).

Each ICD-10 code starts with a capital letter from A to Z. The letters broadly categorize the nature of the diagnosis as follows:

• A: Infectious and parasitic diseases
• B: Infectious and parasitic diseases
• C: Cancer
• D: Neoplasms, blood, and blood-forming organs
• E: Endocrine, nutritional, or metabolic
• F: Mental and behavioral disorders
• G: Nervous system
• H: Eyes, ears, nose, and throat
• I: Circulatory system
• J: Respiratory system
• K: Digestive system
• L: Skin
• M: Musculoskeletal system
• N: Genitourinary system
• O: Pregnancy and childbirth
• P: Perinatal conditions
• Q: Congenital and chromosomal abnormalities
• R: Abnormal clinical and lab findings
• S: Injury, poisoning, and other external causes
• T: Injury, poisoning, and other external causes
• U: Used for emergency designation
• V: External causes of morbidity
• W: External causes of morbidity
• X: External causes of morbidity
• Y: External causes of morbidity
• Z: Factors influencing health status and contact with health services

Thereafter, additional numbers and letters help specify and characterize the condition. For example, E10.9 stands for type 1 diabetes and E11.9 is type 2 diabetes.

How ICD Codes Are Used

ICD codes are used in billing, treatments, and statistics collection. Having the right code is important to ensure that standardized treatment for a medical issue is delivered and that medical expenses are reimbursed.

Insurance Reimbursement

When your healthcare provider submits a bill to an insurance company for reimbursement, each service is described by a common procedural technology (CPT) code. It is matched to an ICD code. If the two codes don't align correctly with each other, the company may deny payment.

In other words, if the service isn't one that would typically be provided for someone with that diagnosis, an insurance company will not pay.

For example, your healthcare provider should not submit a bill for an X-ray if you come in complaining of a rash since imaging is not indicated for that concern.

Disease Management

An ICD code is assigned to every disease. If you have a chronic illness, such as diabetes or heart disease, your ICD code will typically follow your medical records.

In a hospital setting, this can be lifesaving. But for patients with chronic conditions who come to the hospital for an unrelated issue, this can cause frustration.

When you meet a new healthcare provider, they may ask questions about the chronic illness first instead of focusing on your reason for being in the hospital. However, while a condition may seem unrelated to you, there may be a connection known only to the physician.

This process makes sense when you consider that about 80% of "older adults" have at least one chronic health condition while 50% have two or more.

Still, this reality sometimes results in a provider ordering unnecessary tests and treatments that are indicated for the chronic condition rather than focusing on the concern that caused you to seek treatment.

Other Uses

ICD codes are used globally to track health statistics and causes of death. This is helpful for gathering data on chronic illnesses as well as new ones. For example, a new code was added to the ICD-10 in 2020 to track vaping-related illnesses.

ICD codes are also used in clinical trials to recruit and track subjects and are sometimes, though not always, included on death certificates.

Summary

The International Classification of Diseases (ICD) is a tool that assigns codes for diseases, symptoms, abnormal findings, and external causes of a disease or injury. Insurance companies expect the codes, called ICD-10 codes, to be consistent between a condition and the treatment delivered.

If they are not, a claim or authorization may be denied. Learning how to look up an ICD-10 code can help you overcome errors that might otherwise affect you financially or medically.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

1. Centers for Disease Control and Prevention. International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM).
2. CMS.gov. 2023 ICD-10-PCS.
3. Centers for Medicare & Medicaid Services. ICD-10 implementation guide for payers.
4. Centers for Disease Control and Prevention. Depression is not a normal part of growing older.
5. Centers for Disease Control and Prevention. New ICD-10-CM code for vaping-related disorder to be implemented April 1, 2020.

By Trisha Torrey
Trisha Torrey is a patient empowerment and advocacy consultant. She has written several books about patient advocacy and how to best navigate the healthcare system.

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