Difflam throat spray contains benzydamine hydrochloride, which acts locally in the throat to relieve symptoms of irritation and inflammation. While benzydamine is classified as a NSAID (non steroidal anti-inflammatory drug), it doesn't appear work in the same way in terms of its mechanism of action.
It doesn't inhibit COX (cyclooxygenase) or lipooxygenase, two major factors in the inflammatory process. In addition, it doesn't appear to increase the risk of ulcer formation like many other NSAIDs (e.g. Ibuprofen and naproxen). As such, there are no listed or reported interactions with oral, systemic NSAID medications and may be safe to use with other anti-inflammatory medications.
Be sure to speak with your doctor regarding the best over the counter pain medicaiton for your specific condition.