Kindly find attached an article on analgesic activities of flavonoids. Antipyretic activity of medicinal plants may be atributed to alkaloids and non-steroidal anti-inflammatory drugs (NSAIDS). I have attached another document on the same. Hope this will be useful.
As per your question, the answer is not only flavonoids but also other groups of phytochemical constituents may be showing synergistic effect in terms of analgesic and antipyretic activity.
Dr. Harisingh Gour University
Teledyne ISCO, Inc