The effects of acetylsalicylic acid on swelling, pain and other events after surgery.

In a double-blind crossover study acetylsalicylic acid (ASA) in low (2 g daily) or high (4 g daily) dosage was tested against placebo in two groups of 20 patients who each underwent identical oral surgical procedures on two separate occasions. Medication started 3 h post-operatively and continued for 3 days. ASA in low dosage tended to increase the postoperative swelling, which on day 3 and 6 averaged 109 and 133% respectively of that with placebo (P greater than 0.05). In contrast, ASA in high dosage tended to reduce the swelling, which on day 3 and 6 averaged 85 and 90% respectively of that with placebo (P greater than 0.05). Comparison of the two groups receiving ASA in low or high dosage revealed a significant difference in their effect on swelling; day 3, P = 0.05. Pain was significantly reduced with ASA, but there appeared to be no greater analgesic effect with 4 g ASA daily than with 2 g ASA daily. There was, however, a substantial increase in the number of patients who reported tinnitus after taking 4 g ASA daily. Subjective postoperative bleeding scores were significantly increased with 2 g ASA daily, but not with 4 g ASA daily. None of the dosages of ASA appeared to reduce the swelling as efficiently, give better pain relief, or as high preference scores as previously obtained in studies when paracetamol and short term glucocorticoid administration were tested against placebo in this model.