Effects

• Aspirin relieves pain by inhibiting certain chemicals released by the body upon injury. These chemicals, called prostaglandins, enhance the inflammatory response that occurs at the site of injury. They signal pain receptors in the skin and the feeling of pain is amplified.
  
  Thromboxane A2 is an especially important prostaglandin derivative and part of the inflammatory response. Thromboxane A2 attracts platelets and boosts vasodilation. Aspirin specifically inhibits Thromboxane A2 by interacting with the enzyme responsible for its synthesis. This enzyme, cyclooxygenase, is abbreviated as COX. Cyclooxygenase has three forms, or isoenzymes, that retain the same enzymatic properties: COX-1, COX-2 and COX-3. Aspirin is a COX-1 and COX-2 inhibitor.
  
  

Benefits

• In addition to pain relief, aspirin has a powerful anticoagulation effect. This is beneficial to patients with heart or vascular system disease. Many patients with these conditions are prescribed a small, prophylactic dose of buffered aspirin.
  
  

Considerations

• The elderly and the very young, who are susceptible to injuries and falls, are at risk for excessive bleeding and other complications when using aspirin.
  
  Pregnant women should also avoid aspirin, especially during the third trimester. This is important because aspirin's prostaglandin inhibitory effect can interfere with labor and may cause hemorrhage in the mother or the baby.
  
  Aspirin allergy is another serious condition that should be taken under consideration when choosing aspirin for pain relief. Patients with a history of asthma commonly have aspirin allergies.
  
  

History

• Aspirin belongs to a family of chemicals called the salicylates. These are a group of analgesics, or pain relievers, derived from salicin. Salicin is a naturally occurring substance found in willow bark and other plants. The ancient Greek physician, Hippocrates, recommended that his patients relieve their pain by chewing on willow bark.
  
  

Warning

• Aspirin is contraindicated for children, adolescents and even adults who are recovering from viral infections such as the flu. These patients could develop Reye's Syndrome. Aspirin should be taken with caution under the direction of a health-care provider.