Opioids may increase the risk of adverse effects especially respiratory depression. Use of ASA may be associated with the development of Reye's syndrome in children and teenagers with acute febrile illnesses, especially influenza and varicella. Although a direct causal relationship has not been established, salicylates should not be administered to, or used by, children or teenagers who have chickenpox or manifest flu symptoms before a physician or pharmacist is consulted about Reye's syndrome, a rare and serious illness. Pediatric patients are especially susceptible to overdose of caffeine and its adverse CNS effects. Regular use of opioids by pregnant women may cause withdrawal symptoms in the neonate.
Salicylates increase the effects of oral anticoagulants.
Caution is necessary when salicylates and anticoagulants are prescribed concurrently. Also, salicylates may depress the concentration of prothrombin in the plasma. Salicylates may potentiate sulfonylurea hypoglycemic agents. Large doses of salicylates may have a hypoglycemic action, and thus, affect the insulin requirements of diabetics. Although salicylates in large doses are uricosuric agents, smaller amounts may depress uric acid clearance and thus decrease the uricosuric effects of probenecid, sulfinpyrazone and phenylbutazone.