When preparing for the NCLEX, one of the most high-yield areas for every nurse and RN nurse is recognizing red flag signs. These are warning signs that signal something is seriously wrong and require immediate nursing intervention or notifying the healthcare provider. As a registered nurse, being able to identify these early can be lifesaving, both in the exam and in clinical practice.
This guide breaks down the most important red flag signs by system, giving you a quick reference that pairs perfectly with any nursing bundle or study sheet.
🫁 Respiratory System Red Flags
Breathing issues are some of the most urgent problems you’ll see as a nurse. Watch out for:
- Stridor – Indicates airway obstruction (common in croup, epiglottitis).
- Respiratory rate <10 or >60 in children – Danger for respiratory failure.
- Accessory muscle use, nasal flaring, retractions – Signs of distress.
- O2 saturation <90% despite oxygen therapy – Emergency intervention needed.
👉 On the NCLEX, always prioritize airway and breathing first (ABC principle).
❤️ Cardiovascular System Red Flags
Circulatory compromise can escalate fast. Look for:
- Chest pain unrelieved by nitroglycerin – Possible myocardial infarction.
- Sudden onset of cold, pale, pulseless limb – May indicate arterial occlusion.
- BP that drops suddenly (hypotension with tachycardia) – Shock.
- New murmur in a child – Could signal congenital heart disease or endocarditis.
👉 As a nursing student or RN nurse, remember: unstable vital signs always demand immediate action.
🧠 Neurological System Red Flags
Changes in the brain and nervous system are subtle but critical:
- Sudden confusion, agitation, or restlessness – Could indicate hypoxia or stroke.
- Unequal pupils or sudden loss of consciousness – Increased intracranial pressure.
- Seizures with no prior history – Emergency evaluation required.
- Headache with stiff neck and fever – Possible meningitis.
👉 For NCLEX prep, know the difference between normal post-seizure (postictal) states vs. true emergencies.
🩺 Gastrointestinal System Red Flags
Some abdominal findings should never be ignored:
- Rigid, board-like abdomen with severe pain – Peritonitis.
- Bloody stools or vomit (“coffee-ground emesis”) – GI bleeding.
- Projectile vomiting in infants – Possible pyloric stenosis.
- Absent bowel sounds post-op – May indicate paralytic ileus.
🧪 Renal & Urinary Red Flags
Nurses should always assess elimination closely:
- Urine output <30 mL/hr in adults – Renal failure risk.
- Dark, tea-colored urine in a child after infection – Possible glomerulonephritis.
- Sudden severe flank pain with hematuria – Kidney stone or obstruction.
🧍♀️ Musculoskeletal / Skin Red Flags
Even “less urgent” systems can hide emergencies:
- New onset paralysis or inability to move limb – Possible spinal injury.
- Compartment syndrome signs: pain out of proportion, paresthesia, pulselessness – Orthopedic emergency.
- Petechiae or purpura with fever – Meningococcemia, life-threatening.
💡 Quick NCLEX Tip for Nurses
When answering NCLEX-style questions:
- Always prioritize Airway, Breathing, Circulation (ABC).
- Identify unstable patients by looking for these red flags.
- Never ignore sudden changes in vital signs, mental status, or pain.
📝 Final Thoughts for Nursing Students & RNs
Recognizing red flag signs is one of the most critical nursing skills. Whether you’re a student prepping for the NCLEX, a registered nurse in practice, or using a nursing bundle to study, keep these early warning signs in mind. Acting fast can prevent complications and save lives.