LessonsPharmacological and Parenteral Therapies
Adverse effects worth recognizing on sight
Name the drug reactions that are emergencies, distinguish them from expected effects, and say what the nurse does first for each.
The ones that are emergencies
- Anaphylaxis: facial swelling, wheeze and hypotension within minutes of a dose. Stop the drug, call for help, expect epinephrine.
- Neuroleptic malignant syndrome, on an antipsychotic: rigidity, very high fever, altered consciousness, unstable pulse and pressure.
- Serotonin syndrome, on serotonergic drugs together: agitation, tremor, hyperreflexia, fever, diarrhea. Onset in hours rather than days.
- Opioid respiratory depression: falling rate and rousability, saturation last.
- Extravasation of a vesicant: burning at the site, then swelling and no blood return. Stop the infusion, leave the catheter in place, and follow the antidote protocol.
Rigidity with fever on an antipsychotic and rigidity with fever on a serotonergic combination look alike. The clue is usually the drug list and the speed of onset.
Effects that are expected and taught, not reported
- Rifampin turns urine, sweat and tears orange.
- Phenazopyridine turns urine dark orange and stains contact lenses.
- Metronidazole gives a metallic taste, and alcohol with it causes vomiting.
- Iron darkens the stool and causes constipation.
- Statins may cause mild muscle ache — but unexplained widespread muscle pain with dark urine is reported.
- ACE inhibitors cause a dry cough in a proportion of clients; angioedema is the one that is an emergency.
The distinction matters twice: a client who is not warned about the harmless ones stops the drug, and a client who is not warned about the serious ones does not call.
Narrow therapeutic ranges
A few drugs cause harm at levels close to the ones that help, so their toxicity is a routine consideration rather than a rare event.
- Digoxin: visual halos, nausea, anorexia, bradycardia. A low potassium makes toxicity likelier at any level.
- Lithium: coarse tremor, slurred speech, confusion. Anything that loses fluid and sodium — vomiting, diarrhea, a thiazide, hot weather — raises the level.
- Phenytoin: nystagmus, ataxia, slurred speech, and gum overgrowth over months.
- Theophylline: tachycardia, restlessness, seizures.
- Warfarin: judged by the INR rather than by symptoms, until there is bleeding.
Worth remembering
- Anaphylaxis, neuroleptic malignant syndrome, serotonin syndrome and extravasation are stop-now events.
- Orange urine on rifampin and dark stool on iron are taught in advance, not reported.
- A low potassium makes digoxin toxic at a level that would otherwise be safe.
- Anything that dehydrates a client on lithium raises the lithium level.