An adverse drug reaction is any noxious, unintended, and undesired response that occurs at doses normally used in humans for prophylaxis, diagnosis, or therapy. Unlike a predictable side effect, an ADR often requires stopping the medication or changing the treatment plan. Nurses must distinguish between a simple side effect, which is a known secondary action of a drug, and an adverse reaction, which poses a clinical hazard to the patient. Recognizing this distinction early prevents minor drug toxicities from escalating into life-threatening emergencies.
The Rawlins-Thompson classification divides adverse drug reactions into two main types based on dose dependency and predictability.
A common misconception is that all unexpected reactions are Type B; however, many are simply predictable toxicities occurring at the upper limit of a normal therapeutic range.
Certain individuals carry a higher chance of experiencing adverse drug reactions due to biological and environmental variables. Age plays a massive role; neonates and older adults have altered drug clearance pathways. Renal and hepatic impairment drastically reduce metabolism and excretion, leading to drug accumulation in tissues. Genetic polymorphisms can also alter enzyme activity, turning a standard drug dose into a toxic overdose for that specific patient.
Spotting an adverse drug reaction requires vigilant nursing surveillance and a high index of suspicion. Nurses must review the patient's complete medication history, including over-the-counter remedies and herbal supplements common in local practice. Every new symptom in a hospitalized patient should prompt the nurse to ask: could this be caused by a drug? Laboratory results, vital signs, and physical changes must be continuously correlated with the administration times of newly introduced drugs.
Managing an adverse drug reaction starts with immediate withdrawal of the offending agent when clinically feasible. Supportive care is then initiated, ranging from simple antihistamines for mild rashes to emergency resuscitation for anaphylactic shock. Prevention relies on careful allergy screening before drug administration, dose adjustments for organ dysfunction, and reconciling medications at every transition of care. Clear communication between doctors, pharmacists, and nurses closes the safety gaps that allow drug mishaps to reach the patient.
Pharmacovigilance is the science and activities relating to the detection, assessment, understanding, and prevention of adverse effects. In Nigeria, the National Agency for Food and Drug Administration and Control (NAFDAC) oversees this safety monitoring through the Pharmacovigilance Centre. Healthcare professionals use the spontaneous reporting system, often via the national yellow form, to log suspected adverse drug reactions. Proper reporting feeds into a global database, helping regulatory bodies issue safety alerts, restrict dangerous drugs, or update prescribing guidelines across the country.