Recent studies have suggested that ASA usage may be associated with the development of Reye's syndrome in children, teenagers and young adults with acute febrile illnesses, especially influenza and varicella. Although a direct causal relationship has not been established, it is recommended that salicylates be avoided when possible in children, teenagers and young adults with influenza or varicella until the nature of the possible association between ASA and Reye's syndrome has been clarified. The concurrent use of orphenadrine and propoxyphene need not be avoided when indicated. If toxic CNS effects occur, they are probably due to either drug alone and require a reduction in the dose or discontinuation of one or both agents. Salicylates should be administered with caution to patients with asthma and other allergic conditions, with a history of gastrointestinal ulcerations, with bleeding tendencies, with significant anemia, or with hypoprothrombinemia.
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. Salicylates can produce changes in thyroid function tests.