06 Adverse Reactions and Medication Emergencies

Understand medication-related effects

Medicines can cause unwanted effects even when they are correctly prescribed and administered. A new or worsening symptom after a dose deserves attention, particularly if it is severe, unexpected, or affects more than one body system. Symptoms alone may not show which medicine caused a problem, so report observations promptly rather than assuming a cause.

A reaction may appear soon after a dose or develop over time. Its nature can vary with the medicine, dose, route, timing, and patient. Review the medication’s current labeling and the patient’s history; do not treat a single symptom as proof of a particular reaction.

Distinguish the types of reactions

Several related terms describe different aspects of a problem. A Side effect is an unwanted effect that may be predictable from a medicine’s pharmacologic action, such as drowsiness with some antihistamines. It is not necessarily an allergy.

An Adverse drug reaction (ADR) is a harmful or unintended response associated with a medicine. It may occur at a usual dose or result from an interaction or individual sensitivity. An Adverse event is an unwanted medical occurrence during or after medicine use, even when the medicine’s role is uncertain.

A Drug allergy is an immune-mediated reaction. Hives, itching, or swelling may occur, and a severe reaction can cause anaphylaxis; nausea by itself is generally not evidence of allergy. Toxicity refers to harmful effects from excessive drug exposure or accumulation, which can follow an overdose, a dosing error, an interaction, or impaired drug clearance.

Recognize emergency warning signs

Watch for changes in breathing, skin or mucous membranes, alertness, blood pressure, heart rate, pain, bleeding, or relevant laboratory results. Give particular attention to symptoms that are severe, unexpected, worsening, or involve more than one body system.

Treat the situation as an emergency if the person has trouble breathing; wheezing or noisy breathing; swelling of the tongue or throat; collapse or fainting; a seizure; inability to wake; or rapidly worsening symptoms. Anaphylaxis may also involve widespread hives, flushing, vomiting, abdominal pain, dizziness, or low blood pressure. Skin symptoms are not always present.

Respond safely to a suspected reaction

1. Stop and assess. Stay with the person, check responsiveness and airway, breathing, and circulation, and obtain vital signs if trained and able. Note when the medicine was given and when symptoms began.

2. Get help promptly. Activate the facility’s emergency response or call 911 for a life-threatening reaction. In a healthcare setting, notify the responsible clinician and follow local emergency protocols. Do not leave an unstable person alone.

3. Treat suspected anaphylaxis without delay. Epinephrine is the first-line treatment. Give prescribed or protocol-authorized epinephrine and call emergency services. Do not delay epinephrine while waiting for an antihistamine to work. Continue monitoring and follow emergency-team instructions.

4. Seek expert advice for a possible overdose, wrong medicine, or dosing error. In the United States, call Poison Control at 1-800-222-1222. Call 911 for collapse, seizure, difficulty breathing, or inability to wake. Do not induce vomiting or give a home remedy unless directed by a poison specialist or clinician.

5. Prevent further exposure. Do not give another dose of a suspected causative medicine until a qualified clinician has promptly reviewed the situation and provided instructions. Do not independently stop or change other ongoing treatment without clinical advice.

6. Reassess and communicate. Observe for changes, relay the patient’s condition and medicine details to the clinician, and follow the care plan. Mild symptoms can still need timely professional advice, particularly if they worsen or recur.

Document and report medication problems

Record objective facts promptly in the health record. Include the medicine name, strength, dose, route, and administration time; symptom onset and progression; relevant assessment findings and vital signs; actions taken; people notified and when; treatment and response; and the outcome or follow-up plan. Include other medicines, allergies, and relevant history when known. Distinguish observed facts from suspected causes.

Follow workplace policy to report events internally, including medication errors and near misses, whether or not harm occurred. The health record documents the patient’s condition and care; use the organization’s separate safety-reporting process as required. In the United States, patients, consumers, and healthcare professionals can also voluntarily report suspected serious medicine-related problems to FDA MedWatch. A report does not require certainty that the medicine caused the event.

For a suspected allergy, document the specific medicine and the actual reaction, timing, and severity. Avoid recording an unverified side effect as a confirmed allergy. Communicate the information to the care team so it can be assessed and the medication record updated appropriately.

Apply the response to two situations

If a patient feels mildly nauseated after a dose but is alert, breathing normally, and has no other symptoms, record and report the symptom, check the medication instructions, and seek clinical guidance about whether treatment should change. If the patient instead develops tongue swelling and difficulty breathing, activate emergency help and follow the anaphylaxis protocol immediately.