Red flags every medical student should know

Most patients with a headache, back pain or a cough have something benign. A small number don't. Red flags are the features in the history or examination that should make you stop and think: could this be serious, and does it need action today?

Learning them isn't about frightening yourself. It's about knowing which questions you must never skip.

Headache

• Sudden, severe onset, often described as the worst headache ever
• Fever, neck stiffness or a rash
• New neurological symptoms or signs, such as weakness, confusion or visual loss
• A new headache in an older patient, or one with scalp tenderness or jaw pain on chewing
• Headache that is worse on lying down or with coughing and straining
• A history of cancer or a weakened immune system

Chest pain

• Pain brought on by exertion, or radiating to the arm, jaw or back
• Associated sweating, nausea, breathlessness or collapse
• Sudden, tearing pain going through to the back
• Pleuritic pain with breathlessness, especially with risk factors for clots
• Abnormal observations

Back pain

• New bladder or bowel dysfunction, or numbness around the saddle area
• Progressive weakness in the legs
• Fever, weight loss or a history of cancer
• Significant trauma, or minor trauma in someone at risk of fractures
• Pain that is constant and worse at night

Abdominal pain

• Signs of peritonism, such as guarding and rigidity
• Pain out of proportion to the examination findings
• Vomiting blood, or black, tarry stools
• In women of reproductive age, a missed period, since ectopic pregnancy must be considered
• Signs of shock

Breathlessness

• Inability to complete sentences
• Low oxygen saturations, cyanosis or exhaustion
• Sudden onset, especially with chest pain
• Confusion or reduced consciousness

Unexplained weight loss and other "systemic" flags

• Weight loss that the patient can't explain
• Night sweats and persistent fever
• A new lump, or bleeding from anywhere unexpected
• Difficulty swallowing that is getting worse

In children

• Drowsiness, floppiness or being hard to wake
• A non-blanching rash
• Signs of dehydration, such as reduced wet nappies
• Breathing difficulty, grunting or long pauses in breathing
• Parental concern that something is very wrong, which should always be taken seriously

How to actually ask

Red flags only help if you ask about them. A few tips:

1. Ask them explicitly. Patients often don't volunteer symptoms they think are unrelated, like a change in bladder function with back pain.
2. Use plain language. "Have you had any trouble passing urine or controlling your bowels?" is clearer than medical terms.
3. Document the negatives. Recording that red flags were absent shows you thought about them.
4. Escalate early. If a red flag is present, tell a senior. Nobody will mind an unnecessary question; everybody minds a missed diagnosis.

Practise asking, not just knowing

It's easy to recite red flags and still forget to ask in the moment. In Sushruta, patients hold back some details until you ask the right question, and the history axis of your grade shows when you skipped an important screen. Make red flag questions a habit, not an afterthought.

This list is a starting point for study, not a complete clinical guideline. Learn the red flags for your own specialty and follow local guidance in practice.