ICD-10 Code E66.1 – Drug-induced obesity (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E66.1 – Drug-induced obesity
What it is
E66.1 identifies obesity that is caused or worsened by a medication. Use it when the record links weight gain or excess body fat to a drug exposure, rather than to lifestyle or another primary condition.
Clinical signs
Clinical features vary; refer to documentation. Commonly, the chart may note significant weight gain, obesity, or a clinician’s statement that a prescribed drug is contributing to the condition.
When to use this code
Use E66.1 when the provider documents obesity as drug-induced or medication-related. It may appear with a note naming the suspected agent, but you should code only what is documented. If the cause is unclear, check documentation.
This code fits cases where the medication effect is part of the assessment, not merely a past exposure. If obesity is documented without a causal link to a drug, use the more general obesity code instead.
Do not use for
Do not use E66.1 for obesity attributed to diet, inactivity, or other non-drug causes. Do not assign it when the record only mentions weight gain without stating drug-induced obesity.
Coding tip
Look for explicit provider wording tying obesity to a medication; if that link is missing, code the documented obesity type and check documentation.