ICD-10-CM > G00-G99 > G40-G47 > G44 > G44.4 G44.4 Drug-induced headache, not elsewhere classified Non-Billable/Non-Specific Applicable To Medication overuse headache Use Additional code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5) Codes G44.40Drug-induced headache, not elsewhere classified, not intractableG44.41Drug-induced headache, not elsewhere classified, intractable