What Is an Adverse Drug Reaction?

Adverse drug reactions (ADR) are far more commonplace than one would think. It is estimated that ADRs represent the fourth leading cause of death in the United States behind heart disease, cancer, and stroke.

Further, it is estimated that ADRs are the sixth leading cause of death worldwide. A recent meta-analysis of prospective ADR studies estimates that over 180,000 Americans will die from ADRs and over one million will be injured from ADRs every year. Although these data are controversial and the actual incidence of ADRs is impossible to assess, there is no doubt that ADRs have a significant impact on both the healthcare delivery and the drug development industries.

The monetary costs to society due to these ADRs are equally hard to assess accurately, but recent studies have estimated the costs to range from $75 to $180 billion each year for adults alone. When compared to the costs of treating diseases such as diabetes ($45 billion), cardiovascular disease ($120–150 billion), or cancer ($130–195 billion) we begin to truly realize the impact of this aspect of pharmacology on healthcare delivery. Yet another way to demonstrate the impact of ADRs is to realize that approximately 5% of all hospital admissions are a direct result of ADRs, and unfortunately, the incidence has not changed over the past 40 years.

What are ADRs?

The World Health Organization has put forth the definition of ADR as “any response to a drug which is noxious and unintended, and which occurs at doses used in man for prophylaxis, diagnosis or treatment.” In other words, an ADR could be an unexpected or unwanted effect that is a direct extension of the mechanism of drug action; in an organ system that is not the target of drug therapy; an allergic response; a hypersensitive response; an idiosyncratic response (one totally unpredictable); or drug interaction with unexpected results. In each case, the ADR represents an unwanted toxic effect as a result of taking a given drug or set of drugs.

The reaction can start soon after you take the medicine, or up to 2 weeks after you stop. An adverse drug reaction can cause serious conditions such as toxic epidermal necrolysis (TEN) and anaphylaxis. TEN can cause severe skin damage. Anaphylaxis is a sudden, life-threatening reaction that needs immediate treatment.

Signs and symptoms of ADR

Mild symptoms include red, itchy, flaky, or swollen skin. You may have a flat, red area on your skin that is covered with small bumps. You may also have hives. Severe symptoms include skin that blisters or peels, vision problems, and severe swelling or itching. Severe reactions include conditions such as toxic epidermal necrolysis (TEN). Anaphylaxis symptoms include throat tightness, trouble breathing, tingling, dizziness, and wheezing. Anaphylaxis is a sudden, life-threatening reaction that needs immediate treatment. Anaphylaxis may occur if you exercise after exposure to another trigger, such as after you take an antibiotic.

Safety precautions you need to take if you are at risk for ADR

– Read medicine labels before you use any medicine. Do not take anything that contains the medicine you are allergic to. This includes topical medicines that you put on your skin. Ask a pharmacist if you are not sure.

– Tell all healthcare providers about your allergy. Always tell your healthcare providers the names of medicines that you are allergic to and the symptoms of your allergic reactions.

– Ask if you need to avoid other medicines. You may be allergic to other medicines if you had an adverse reaction. Make sure you know the names of other medicines that you should not take.

– Call 911 for signs or symptoms of anaphylaxis, such as trouble breathing, swelling in your mouth or throat, or wheezing. You may also have itching, a rash, hives, or feel like you are going to faint.