ICD-10 Code F16.9 – Hallucinogen use, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F16.9 – Hallucinogen use, unspecified
What it is
F16.9 identifies hallucinogen use when the specific substance is not documented. Use it for records that confirm hallucinogen involvement but do not name the drug.
Clinical signs
Clinical features vary; refer to documentation. Hallucinogen use may be associated with altered perception, mood changes, agitation, or impaired judgment, but the record must support the diagnosis.
When to use this code
Use F16.9 when the provider documents hallucinogen use without identifying the agent, such as LSD, psilocybin, or another hallucinogen. It also fits cases where the substance is known to be a hallucinogen, but the exact drug is not recorded.
If the chart later specifies the substance, code the more specific option instead. Check documentation for whether the encounter reflects use, abuse, dependence, or intoxication, since those may require different coding.
Do not use for
Do not use this code for a fully identified hallucinogen when a more specific code is available. Do not use it for non-hallucinogen substance use or for symptoms alone without documentation of hallucinogen use.
Coding tip
Code to the highest documented specificity, and query the provider if the hallucinogen type or related substance-use category is unclear.