Hi, It is generally not recommended to mix different medications without consulting a doctor or pharmacist first, as there can be potential interactions and side effects. In particular, OxyElite Pro contains caffeine and other stimulants, which can increase heart rate and blood pressure. Combining allergy medication, such as antihistamines or decongestants, with OxyElite Pro can further increase these effects, leading to potential risks such as irregular heartbeats, high blood pressure, and other adverse effects. Additionally, it is important to note that OxyElite Pro has been linked to several cases of liver damage and other serious health complications. The U.S. Food and Drug Administration (FDA) has issued warnings about this product, and it has been banned in several countries. Using weight loss products without proper medical supervision and advice can be dangerous and may result in serious health consequences. Therefore, if you are experiencing allergy symptoms, it is recommended to consult a healthcare provider for appropriate treatment options, rather than trying to self-medicate or mix medications on your own. If you require a personalized response, kindly use the Ask A Doctor service and post a follow-up. Take care. Hope I have answered your question. Regards, Dr. Priyanka, General & Family Physician