Brief Answer: They can be used together Detailed Answer: Hi, thanks for using healthcare magic Though they both help with allergic responses, they are in a different family of drugs and as a result the mechanism of action, metabolism and elimination of the drugs would be different. Antihistamines and steroids are commonly used together for inflammatory conditions. The anti histamines work specifically to block histamine action whereas steroids bind to a specific receptor in the body to affect the release of substances in the body that promote inflammation. Because they are completely different drugs, they can be used together with no additive side effects. There would also be no negative interaction. Allergy testing is available to help determine the source of the allergic response. This can be done as a blood tests or skin prick testing. I hope this helps, feel free to ask any other questions

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