Yes, you can deduct vitamins if they are specifically recommended by your doctor as treatment for your medical condition. If you take them to maintain your general health - they are not deductible.
Per IRS: "You can't include in medical expenses the cost of nutritional supplements, vitamins, herbal supplements, “natural medicines,” etc. unless they are recommended by a medical practitioner as treatment for a specific medical condition diagnosed by a physician.
See Page 16 of Pub 502 - Medical and Dental Expenses