Prescription Requirements. The same deduction rules apply for prescribed over-the-counter medicine and regular prescription drugs. The prescription must be written or transmitted to the pharmacy electronically by a medical professional with the legal authority to prescribe medication.o if a doctor tells you to take 100 mg of aspirin every day, and you go buy a bottle of 100 mg tablets at a drugstore, the cost isn't deductible. But it is deductible if the doctor writes you a prescription for the same bottle.