A 42-years-old female with a long history of asthma and chronic rhinosinusitis experienced frequent asthma attacks after taking NSAIDs for her knee pain.  She wondered “am I allergic to arthritis medication?”

Adverse Drug Reactions (ADRs) are a broad term referring to unwanted, uncomfortable, or dangerous effects that a drug may induce. In the U.S. 3 to 7% of all hospitalizations are due to ADRs.  These reactions occur during 10 to 20% of hospitalizations; about 10 to 20% of these ADRs are severe.  Side effects are the most frequent ADRs and are defined as therapeutically undesirable, but sometimes unavoidable.  A drug frequently results in several pharmacologic reactions, and only one of these may represent the desired therapeutic effect.  The other reactions may be considered side effects.

Aspirin and traditional NSAIDs are well known to suppress the production of inflammatory substances by inhibiting the production of cyclooxygenase (COX, prostaglandin synthase), an enzyme that helps the body produce different kinds of prostaglandins, especially for pain, swelling, and tenderness associated with arthritis or other chronic inflammatory disorders.  Prostaglandins play an important role not only in inflammation but also in protecting the stomach lining, promoting adequate blood clotting, regulating salt and fluid balance, and maintaining blood flow to the kidneys when function is impaired.

Early in the 1990s scientists discovered two types of enzymes involved in different prostaglandin production: cyclooxygenas-1 (COX-1), associated with good prostaglandin that protects the digestive system from our own erosive acids, and cyclooxygenas-2 (COX-2), associated with bad prostaglandin that causes pain, fever and inflammation.

Aspirin and traditional NSAIDs (COX-1 inhibitor), such as Naprosyn and Ibuprofen, not only reduce the “bad” prostaglandins to control inflammation, they also reduce the “good” prostaglandins that protect the stomach lining.  As a result, these effects create an increased risk of stomach irritation, stomach bleeding, fluid retention and decreased kidney function.  Celebrex (Selective COX-2 inhibitors), blocks only pro-inflammatory prostaglandins while leaving the good prostaglandins untouched, preventing stomach ulcers and bleeding.  However, like traditional NSAIDs, it can still decrease kidney function and cause fluid retention.  All NSAIDs should be avoided for patients with poor kidney function.

Moreover, in some patients with asthma, especially when accompanied by chronic rhinosinusitis and nasal polyps, COX-1 inhibitor NSAIDs precipitate asthmatic attacks.  Some patients with chronic idiopathic urticaria experience hives flare-ups after taking Naprosyn or Ibuprofen, but not Celebrex or Mobic.

Some ADRs are due to pharmacologic reactions from drugs instead of being a true drug allergy mediated by our immune system.  For some side effects, the drug can often be switched, or the dose of the drug can be adjusted to produce the maximum desired pharmacologic action with a minimum of undesired effects.