Aspirin should be discontinued at least 1 week before surgery to minimize postoperative bleeding. Intramuscular injections should be administered cautiously to patients receiving aspirin. IM injections may cause bleeding, bruising, or hematomas due to platelet effects secondary to aspirin therapy. Large doses also can cause hypoprothrombinemia, which can be reversed by vitamin K. Similarly, patients with renal insufficiency, renal failure, or vitamin K deficiency should be closely monitored if taking large doses of aspirin. In some patients, even normal doses can cause urticaria.
Asthmatic symptoms can occur, especially in patients with nasal polyps.
Patients with a tartrazine dye hypersensitivity should avoid aspirin. Aspirin recently was studied as an agent to prevent preeclampsia in women who were 13-26 weeks pregnant. Its efficacy in preventing preeclampsia was only marginal, and a higher risk of developing abruptio placentae was seen. There were no differences between groups in birth weight or rates of fetal growth retardation, neonatal bleeding, or postpartum hemorrhage. Nevertheless, aspirin is classified as pregnancy category C during the first and second trimesters and should be used cautiously.