Yes. The costs incurred in an addiction treatment facility is absolutely a medical expense and as such qualifies as a deduction for those who itemize and whose expenses exceed 7.5 percent of their income.
Reference: Revenue Ruling 73-325,, Internal Revenue Service, (Jan. 1, 1973)
Section 213.–Medical, Dental, Etc., Expenses
26 CFR 1.213-1: Medical, dental, etc., expenses.
Amounts paid by an inpatient for treatment at a therapeutic center for alcoholism, and for meals and lodging furnished as a necessary incident to the treatment, are deductible as medical expenses under section 213 of the Code.
