Severe drug hypersensitivity reactions

Severe Drug Hypersensitivity Reactions: A Growing Threat

Drug hypersensitivity reactions (DHRs) are becoming increasingly problematic. DHRs result in an immunological response to a medication or drug and can cause potentially life-threatening side effects. These reactions can occur due to a variety of factors such as genetics, environment, or even the patient’s unique immunological sensitivity.

The World Allergy Organization (WAO) recently outlined the 3 classifications of drug hypersensitivity reactions.

• Type I DHRs involve an IgE-mediated immune response that can quickly lead to severe symptoms.
• Type II hypersensitivity reactions involve an antibody response to drugs bound to specific proteins.
• Type III hypersensitivity reactions are caused by an immune complex deposits of drugs, protein, and antibodies.

Since drug reactions occur at different time frames, diagnosis can be difficult because a causal relationship may not be noticed until a reaction occurs after several weeks of taking a particular medication. Thus, physicians must take extra care when prescribing multiple medications and watch for any signs of an adverse drug reaction.

Severe DHRs are characterized by symptoms such as anaphylaxis, Stevens-Johnson syndrome, and toxic epidermal necrolysis (TEN). Anaphylaxis is an allergic reaction that occurs within minutes of exposure and can lead to death due to a decrease in circulating blood pressure. Stevens-Johnson syndrome is a reaction that leads to the inflammation of the skin, with the formation of blisters or lesions. Toxic epidermal necrolysis is a severe blistering of tissues in the body and can cause systemic organ failure.

Symptoms of severe DHRs can appear differently in lymphocytes, or even macrophages in the bloodstream, making diagnosis difficult. In addition, once the adverse event takes place, the patient may have to wait for weeks before completing the course of treatment.

The widespread proliferation of new medications, as well as more frequently prescribed older medications, has resulted in a growing number of drug hypersensitivity reactions. Thus, it is important for physicians to be aware of the dangers associated with DHRs and the risk factors for individual patients.