Combining paracetamol and other NSAIDs could give a theoretical synergistic analgesic effect according to already known or assumed mechanisms of action. Synergism is defined as an additive or supra-additive effect not achieved by one of the drugs alone. Such synergism is shown in clinical studies between acetaminophen and naproxen in coxarthrosis and rheumatoid arthritis. Later, a significant additive effect of 100 mg diclofenac with 1 g acetaminophen was demonstrated in a dental pain model.