Yes, you can deduct prescriptions. Per IRS Publication 502, medical expenses are broadly defined as "the costs of diagnosis, cure, mitigation, treatment, or prevention of disease, and for the purpose of affecting any part or function of the body. "
See this article for more information: Are Medical Expenses Tax Deductible?
Note that in order to claim medical expenses you must itemize deductions and only the expenses over 7.5% of your AGI are deductible.
