While Acetylsalicylic Acid (Aspirin) is a widely used and generally safe medication when taken as directed, understanding its potential side effects, contraindications, and drug interactions is paramount for safe and effective use. Awareness of these aspects ensures that individuals can make informed decisions about their health.

Common Side Effects:

The most frequently reported side effects of Aspirin are related to the gastrointestinal system due to its inhibition of COX-1, which plays a protective role in the stomach lining. These can include:

  • Upset stomach, heartburn, nausea, and vomiting.
  • Increased risk of stomach irritation, ulcers, and bleeding.

Other common side effects can include ringing in the ears (tinnitus), especially at higher doses.

Serious Side Effects and Warnings:

While less common, some side effects require immediate medical attention:

  • Bleeding: Increased risk of bleeding anywhere in the body, including gastrointestinal bleeding (black, tarry stools; vomiting blood), or hemorrhagic stroke (sudden severe headache, weakness, vision problems).
  • Allergic Reactions: Symptoms like rash, itching, swelling (especially of the face, tongue, throat), severe dizziness, or trouble breathing.
  • Reye Syndrome: A serious, though rare, condition that can affect the brain and liver, primarily in children and teenagers recovering from viral infections like flu or chickenpox. This is why Aspirin is generally not recommended for individuals under 16 years of age for fever or pain.
  • Kidney Problems: Long-term use or high doses can potentially affect kidney function.

Contraindications: Who Should Avoid Aspirin?

Certain individuals should avoid Aspirin or use it only under strict medical supervision:

  • Individuals with known hypersensitivity or allergy to Aspirin or other NSAIDs (like ibuprofen or naproxen).
  • Those with active stomach ulcers or a history of gastrointestinal bleeding.
  • Individuals with bleeding disorders or those taking anticoagulant medications.
  • People with severe kidney or liver disease.
  • Asthmatics, particularly those with Aspirin-exacerbated respiratory disease (AERD).
  • Children and teenagers under 16 years old, as noted above.

Drug Interactions:

Aspirin can interact with various medications, altering their effectiveness or increasing the risk of side effects. Key interactions include:

  • Anticoagulants and Antiplatelet Drugs: (e.g., Warfarin, Clopidogrel) – Significantly increases the risk of bleeding.
  • Other NSAIDs: (e.g., Ibuprofen, Naproxen) – Can increase the risk of gastrointestinal side effects and potentially reduce Aspirin's cardioprotective effect.
  • Corticosteroids: Increases the risk of gastrointestinal bleeding.
  • Certain Blood Pressure Medications (e.g., ACE inhibitors, diuretics): May reduce their effectiveness.
  • Methotrexate: Aspirin can increase methotrexate levels, raising the risk of toxicity.
  • Alcohol: Concomitant use with Aspirin increases the risk of stomach bleeding.

It is imperative that all individuals inform their healthcare provider about all medications, supplements, and herbal products they are taking to avoid potentially harmful aspirin drug interactions. Understanding these safety considerations is as crucial as understanding the acetylsalicylic acid uses and its mechanism.