REASONING GP · Clinical algorithm · Quick reference

Breathlessness in adults — triage and diagnostic approach

Daytime GP and OOH/111, face-to-face or remote. Measure before you reason, screen for the acute life-threats, then separate cardiac from respiratory from systemic to a named diagnosis.
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AdultsGP + OOHDiagnosis firstv1.0 · Sep 2026
Core rule. Breathlessness is a measurement, not an impression: RR, SpO₂, pulse and BP come before the history. A normal-looking patient with RR ≥25 or SpO₂ <94% is an acute-care decision. New hypoxia, new tachycardia or breathlessness at rest is never "just anxiety" or "just their COPD" until measured.
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Before any history: is this an emergency now? Stop the consultation and call 999 if any of these is present
Cannot speak in sentences, silent chest, exhaustion, cyanosis, agitation or drowsiness · SpO₂ <92% on air or below target · RR ≥25 or rising · pulse >120 or <40, systolic BP <90 · life-threatening asthma (PEF <33%, silent chest, poor effort, bradycardia, confusion — NG245) · stridor, drooling, facial or tongue swelling · silent hyper-resonant hemithorax or tracheal deviation · suspected anaphylaxis. Sit upright, oxygen to target, IM adrenaline 500 micrograms if anaphylaxis, salbutamol via spacer if wheeze, hand over with observations and times. Do not delay transfer for a CXR, bloods or an ECG.
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Measure, then define the breathlessness in four lines Enough to place the patient in the table below; the full history can wait

Measure first

RR over a full minute, SpO₂ on air (and the usual reading), pulse, BP, temperature, GCS; peak flow if wheeze; NEWS2. A fall of 3% from a previous SpO₂ matters even if the number looks fine.

Time course

Minutes (pneumothorax, PE, anaphylaxis, arrhythmia) · hours to days (asthma, infection, heart failure, ACS) · weeks to months (COPD, anaemia, effusion, cancer, fibrosis). Episodic and fully resolving suggests asthma, arrhythmia or panic.

Pattern and posture

Orthopnoea and paroxysmal nocturnal dyspnoea (heart failure) · exertional limit in metres or flights, and how it changed · wheeze, cough, sputum, haemoptysis · chest pain, palpitations, syncope · better on holiday (occupational).

Context

Known asthma, COPD, heart failure, IHD, cancer · inhaler technique, adherence, steroid courses this year, previous ITU · pack-years, asbestos, occupation · immobility, surgery, pregnancy/postpartum, oestrogen · amiodarone, methotrexate, nitrofurantoin.
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Red-flag screen: trigger → concern → destination → what to do before handover One row is enough; do not add up reassuring features
Trigger / red flagLeading concern · destinationDo now · do not delay
Acute severe or life-threatening asthma: PEF <50% (severe) or <33% (life-threatening), RR ≥25, pulse ≥110, cannot complete sentences; silent chest, cyanosis, poor effort, confusion, SpO₂ <92% (NG245). Acute asthma
999 now if life-threatening, SpO₂ <92% or no response		 Salbutamol 4–10 puffs via spacer, one puff at a time, every 10–20 minutes, or nebulised 5 mg. Prednisolone 40–50 mg for 5 days (NG245). Oxygen to 94–98%. Never discharge after a nebuliser without repeating PEF and SpO₂.
Pleuritic pain or sudden breathlessness with hypoxia, pulse >100, haemoptysis, unilateral leg swelling, syncope; immobility, surgery, cancer, pregnancy or 6 weeks postpartum, oestrogen. Pulmonary embolism / pneumothorax
999 if hypoxic, hypotensive or syncope Same-day acute assessment		 Two-level PE Wells (NG158). Over 4: immediate CTPA via the acute route, not a D-dimer. 4 or less: D-dimer only if same-day, interim anticoagulation if delayed. Pregnancy or postpartum: no D-dimer, no Wells — direct maternity assessment (RCOG). Tracheal deviation with hypotension = tension pneumothorax → 999.
Acute heart failure or arrhythmia: breathless at rest, orthopnoea, PND, new crackles, raised JVP, new oedema, pulse >120 or <40 or irregular, syncope; or with chest pain or sweating — breathlessness alone can be the ACS in diabetes, age over 75 and women. Acute heart failure · arrhythmia · ACS
999 now if ACS suspected, unstable or pulmonary oedema		 ECG if it will not delay transfer. Suspected ACS: aspirin 300 mg orally unless allergic; record dose and time (CG95). Sit upright; oxygen only if SpO₂ <94%. Never a diuretic and review.
Airway compromise or anaphylaxis: stridor, drooling, facial, lip or tongue swelling, urticaria with breathlessness or hypotension after a trigger; suspected inhaled foreign body. Anaphylaxis · upper airway obstruction
999 now		 IM adrenaline 500 micrograms (0.5 mL of 1 mg/mL) anterolateral thigh, repeated after 5 minutes if no response; lie flat with legs raised, or sit up if breathing dominates; high-flow oxygen (Resuscitation Council UK). Never rely on an antihistamine. All anaphylaxis is admitted.
Infection with severity features: fever, rigors, purulent sputum, focal signs, confusion; CRB65 — confusion, RR ≥30, BP <90 systolic or ≤60 diastolic, age ≥65 (CG191): ≥3, or 1–2 with hypoxia or frailty, needs hospital. Pneumonia · empyema · sepsis
Same-day acute assessment 999 if sepsis, shock or neutropenic		 Temperature and SpO₂; record CRB65 and NEWS2. CRB65 0 with normal SpO₂: treat at home, review at 48–72 hours (CG191). SpO₂ <94% or NEWS2 ≥5 is an acute-care decision, not an antibiotic and review.
COPD exacerbation not safe at home: SpO₂ below target, marked breathlessness, cyanosis, confusion or drowsiness, new oedema, poor support, or no improvement on a rescue pack (NG115). COPD exacerbation · type 2 respiratory failure
Same-day acute assessment 999 if drowsy or confused		 Salbutamol via spacer or air-driven nebuliser; prednisolone 30 mg for 5 days; antibiotic only if sputum is more purulent or the patient is unwell (NG114/NG115). Oxygen target 88–92% if hypercapnic risk. Drowsiness or headache suggests CO₂ retention: a transfer, not more nebulisers.
Pregnancy or up to 6 weeks postpartum, or cancer / immunosuppressed / anticoagulated, with new or worsening breathlessness. PE · peripartum cardiomyopathy · pre-eclampsia · SVC obstruction · effusion · pneumonitis · anaemia
Same-day maternity / acute / oncology 999 if unstable		 Record gestation or postpartum interval, BP, urinalysis, SpO₂, cancer treatment and anticoagulant. Speak directly to maternity, acute or acute oncology. Facial or arm swelling with distended neck veins is SVC obstruction. Breathlessness on immunotherapy or a pneumotoxic drug is a specialist call.
Age 40 and over with unexplained breathlessness plus cough, fatigue, chest pain, weight loss or appetite loss; or with haemoptysis at any age; ever smoked or asbestos-exposed; clubbing or supraclavicular nodes. Lung cancer · mesothelioma
Urgent CXR within 2 weeks · NG12		 Direct-access urgent CXR (NG12); haemoptysis at 40 and over needs it even with a normal examination. A normal CXR with persisting symptoms still needs a decision on urgent suspected-cancer referral. Breathlessness with anaemia or weight loss needs an urgent FBC (NG12).
Safety rule. A normal chest, a normal peak flow between attacks, a normal CXR and a familiar diagnosis label each reduce probability and exclude nothing. Wheeze can be absent in life-threatening asthma and present in heart failure. Never label new breathlessness as anxiety while RR, SpO₂ or pulse is abnormal.
Colour is semantic: red = emergency now · amber = same-day acute assessment · blue = define/assess · green = primary-care diagnosis established · purple = uncertain, routine specialist or 2WW. Continued on page 2: classification, cause classifier, routine referral, primary-care treatment, endpoint.
REASONING GP · Breathlessness in adults — triage and diagnostic approach
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Focused examination and investigation Remote assessment that cannot measure is an escalation criterion

Observations

RR, SpO₂ on air, pulse rate and rhythm, BP, temperature, GCS; peak flow with best/predicted; NEWS2. Repeat after treatment — the change matters more than the first number.

System examination

Work of breathing, speech, accessory muscles, cyanosis · trachea, percussion, breath sounds, wheeze or crackles and whether unilateral · JVP, heart sounds, oedema, calves · pallor, clubbing, nodes.

Pattern-separating signs

Basal crackles with raised JVP and oedema (heart failure) · stony dullness (effusion) · fine crackles with clubbing (fibrosis) · hyper-resonance with quiet sounds (pneumothorax) · normal chest with tachypnoea and hypoxia (PE, anaemia, acidosis) · normal chest, normal SpO₂ (panic).

Investigations

CXR (urgent if NG12 applies). Spirometry with reversibility, FeNO and a peak-flow diary for asthma (NG245); post-bronchodilator FEV₁/FVC <0.7 for COPD (NG115). NT-proBNP and ECG for heart failure (NG106). FBC, ferritin, U&E, TFT, HbA1c. Not in primary care: CTPA, echo without NT-proBNP triage, steroid trials.
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Classify: three exits, not two "Chest is clear" is not a diagnosis; name the cause or name the uncertainty

Serious cause likely

Any red flag, RR ≥25, SpO₂ below 94% or below baseline, new tachycardia or hypotension, or a high-risk context. Output: name the concern; use the destination above; record observations, treatment and time.

Cause established in primary care

Observations at baseline, and the whole breathlessness explained by one cause below with objective support (spirometry, NT-proBNP, FBC, CXR). Output: record the cause, the findings, and the management pathway entered.

Unclassified / uncertain

Exertional breathlessness with normal resting observations, mixed features, or not improving on treatment. Output: never default to "anxiety" or "deconditioning". State the uncertainty, the exclusions outstanding, the section-6 route where one applies, and who reviews when.
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Cause classifier: what makes each diagnosis, objectively Only once the red-flag screen is negative
AsthmaEpisodic wheeze, cough and breathlessness with diurnal and trigger-related variability, atopy. Objective confirmation before diagnosis (NG245): FeNO ≥50 ppb, FEV₁ improvement of 12% plus 200 mL, or peak-flow variability over 20% on a 2-week diary. Never on symptoms or a salbutamol trial. Better away from work is occupational asthma.
COPDAge over 35 with a smoking or exposure history plus exertional breathlessness, chronic cough or sputum, and post-bronchodilator FEV₁/FVC below 0.7 (NG115). Record the MRC grade. Never diagnose without spirometry. A never-smoker with obstruction needs another explanation.
Chronic heart failureExertional breathlessness with orthopnoea or PND, oedema, raised JVP, basal crackles, previous MI or AF. NT-proBNP and ECG in primary care (NG106): 400–2000 ng/L → echo within 6 weeks; above 2000 → within 2 weeks. Below 400 makes heart failure unlikely but does not explain the breathlessness; obesity and cardiac drugs lower it.
Anaemia, thyroid, metabolic, obesity, deconditioningGradual exertional breathlessness with a normal chest and normal SpO₂. Requires positive findings, not the absence of others: FBC and ferritin, TFT, U&E, HbA1c, weight trajectory. Iron deficiency in a man or postmenopausal woman needs a GI cancer route (NG12).
Breathing pattern disorder / panicBreathlessness at rest that eases on exertion, sighing, air hunger, perioral tingling, episodes peaking within minutes, normal observations throughout. Only after cardiac, respiratory and anaemic causes are addressed objectively. Inducible laryngeal obstruction is often mislabelled asthma.
Do not label by defaultInterstitial lung disease (fine crackles, clubbing, exertional desaturation) needs an urgent CXR and respiratory referral, not an antibiotic. Effusion, SVC obstruction and bronchiectasis are imaging diagnoses. A patient labelled asthma or COPD who is not improving needs spirometry, not another inhaler.
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Refer routinely from this consultation Not same-day, not 999 — the cases that leave by letter
NT-proBNP 400–2000 ng/L → heart-failure specialist and echo within 6 weeks; above 2000 ng/L → within 2 weeks (NG106) · uncertainty after the objective panel, or suspected interstitial lung disease, bronchiectasis or pulmonary hypertension → respiratory · asthma uncontrolled on moderate-dose MART, or 2 or more steroid courses in 12 months → respiratory (NG245) · COPD at MRC grade 3 or above → pulmonary rehabilitation and long-term oxygen assessment (NG115) · suspected occupational asthma → occupational lung service · breathing pattern disorder → respiratory physiotherapy · recurrent panic → NHS Talking Therapies (NG113). What remains below is what primary care treats today.
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The only treatment decisions that belong in this consultation What primary care treats today
AnaphylaxisIM adrenaline 500 micrograms (0.5 mL of 1 mg/mL) anterolateral thigh, repeat after 5 minutes if no improvement; position, high-flow oxygen, 999 (RCUK). Admit every case; two auto-injectors on discharge and an allergy referral.
Acute asthma not needing immediate transferSalbutamol 4–10 puffs via spacer one puff at a time, every 10–20 minutes, or nebulised 5 mg; prednisolone 40–50 mg daily for 5 days; oxygen to 94–98% (NG245). Review within 48 hours, check technique, give a written action plan. No response, or SpO₂ <92%, is an admission.
COPD exacerbation safe at homeIncrease short-acting bronchodilator via spacer; prednisolone 30 mg daily for 5 days; antibiotic only if sputum is more purulent or the patient is unwell (NG114/NG115). Oxygen target 88–92% if at risk of hypercapnia. Review at 48 hours and refresh the rescue pack.
Pneumonia, CRB65 0, SpO₂ normalAmoxicillin 500 mg three times daily for 5 days first line unless penicillin-allergic (CG191, NG138); safety-net and review at 48–72 hours. Repeat CXR at 6 weeks if symptoms persist or lung-cancer risk is higher.
Newly confirmed asthma or COPDStart the NG245 or NG115 ladder only after objective confirmation. Technique demonstrated, spacer supplied, smoking cessation offered, vaccinations checked, written plan, named review date.
What not to doNo diuretic for breathlessness and review without NT-proBNP and an ECG. No community treatment of suspected PE or pneumothorax. No steroid trial as a diagnostic test. No oxygen outside a specialist assessment. No inhaler started on symptoms alone.
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Endpoint and documentation Finish with one of four conclusions

1 · Time-critical serious

999 route taken; suspected diagnosis, RR, SpO₂ on air, pulse, BP, PEF where relevant, treatment with doses and times, oxygen target.

2 · Serious possible

Same-day acute, maternity or oncology assessment arranged; the question being excluded, Wells or CRB65 score, who was spoken to, deadline to be seen.

3 · Cause established

Cause and the objective findings supporting it; observations; management pathway entered; inhaler technique and plan; safety-net understood.

4 · Unclassified

Uncertainty stated; objective panel or referral sent, with date; interim rescue plan; review owner and timeframe; escalation criteria.
Why a primary-care diagnosis is safe today: no row on the page-1 screen applies · RR, SpO₂, pulse and BP at baseline and recorded · the whole breathlessness explained by one cause with objective support · written safety-net and a review with a named owner. Safety-net wording: call 999 if you cannot speak in full sentences, your lips turn blue, you become drowsy, or your breathing suddenly worsens; same-day contact for breathlessness at rest, a reliever lasting under 4 hours, chest pain, coughing blood, a swollen painful leg, or waking breathless.
OOH / remote limitation. Convert to face-to-face or emergency assessment if the patient cannot complete sentences on the call; RR, SpO₂, pulse or peak flow cannot be measured; symptoms are worsening during the call; the patient is pregnant, immunosuppressed or has had ITU admission for asthma; or safe transport cannot be guaranteed.
Clinical decision support only; follow local emergency-transfer, antimicrobial and referral policies and check doses against the current BNF. Source hierarchy: NICE and CKS first, then BNF/MHRA, then national specialty guidance. Sources: NICE NG245 Asthma · NG115 COPD · NG114 COPD exacerbation antimicrobial · CG191 Pneumonia · NG138 CAP antimicrobial · NG106 Chronic heart failure · CG187 Acute heart failure · NG158 Venous thromboembolic diseases · CG95 Chest pain · NG51 Sepsis · NG12 Suspected cancer · NG113 Panic disorder · NICE CKS · BNF · MHRA · BTS Pleural disease 2023 · BTS Emergency oxygen · RCUK anaphylaxis · RCOG Green-top 37b. Review after any guidance or medicines-safety update, otherwise every 6 months. © Reasoning GP · gpreasoning.uk