Respiratory infection triage: cold, flu, pneumonia, and isolation

Respiratory illness is one of the most common emergencies in any austere scenario, and the vast majority of it is viral and self-limiting. The job is not treating every cough — it is recognizing the minority of cases that are not viral, that have crossed into bacterial pneumonia or respiratory failure, and where the decision to start an antibiotic or escalate could save a life. Without a chest X-ray or a laboratory, that decision rests entirely on numbers you can measure at the bedside: pulse oximetry, respiratory rate, temperature, and mental status.

Educational use only

This page provides general educational information for emergency preparedness scenarios when professional medical care is unavailable. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider. Use this information at your own risk.

Before you start - Skills: Count respiratory rate accurately for a full 60 seconds using a watch with a second hand. Operate a pulse oximeter. Assess mental status using AVPU (Alert / Verbal / Pain / Unresponsive). No clinical training required for initial triage. - Materials: Pulse oximeter (finger-clip, inexpensive) and thermometer (digital). Watch with second hand or phone timer for RR. Stockpiled amoxicillin and doxycycline per medical stockpiling. - Antibiotic thresholds: Empiric antibiotic criteria per ATS/IDSA Community-Acquired Pneumonia 2019 guideline (Metlay et al., AJRCCM 200:e45-e67). Do not start antibiotics unless pneumonia criteria below are met — most respiratory illness is viral. - Pediatric fever thresholds: Any neonate (<28 days) with fever ≥100.4°F (38°C) rectal = emergency room, no exceptions, per AAP Fever and Antipyretic Use in Children (2022). - Pulse oximetry target: SpO2 ≥94% on room air per WHO pulse oximetry training guidelines (2011). Values <94% are abnormal; <90% is severe hypoxia requiring immediate intervention.

Action block

Do this first: Measure and record the sick person's pulse oximetry and respiratory rate once — these two numbers determine the urgency of every decision that follows (active time: 3 minutes). Time required: Active: 3 minutes for initial triage; reassessment every 4–6 hours during active illness. Cost range: Inexpensive for a finger-clip pulse oximeter and digital thermometer; affordable for a stockpiled amoxicillin and doxycycline supply. Skill level: Beginner for vital sign measurement and isolation setup; intermediate for syndrome classification; advanced for empiric antibiotic selection in comorbid patients. Tools and supplies: Tools: finger-clip pulse oximeter, digital thermometer, watch or phone timer. Supplies: amoxicillin 500 mg capsules, doxycycline 100 mg capsules, surgical masks, nitrile gloves per stockpiling. Safety warnings: See Sputum color is unreliable below — green or yellow sputum alone does not justify antibiotics and is a common decision error.

Viral first: why most antibiotics are wrong here

The overwhelming majority of acute respiratory illness — common colds, bronchitis, influenza-like illness, respiratory syncytial virus (RSV) in adults, and most COVID-19 presentations — is caused by viruses. The body's immune system resolves these infections within 5–14 days without antibiotics. This is not a recommendation to do nothing — it is a recognition that the correct treatment is supportive care, and that adding an antibiotic to a viral illness provides no benefit while carrying real risks.

Antibiotics do not treat viruses. They have no mechanism of action against viral pathogens. Starting amoxicillin for a cold does nothing for the infection and actively disrupts gut flora, increases the risk of Clostridioides difficile colitis, and contributes to antibiotic resistance in the community. The pathogens page contains the full explanation of why different organism classes require different treatments — read it before reaching for the antibiotic supply.

Standard viral URI course: Most colds and uncomplicated flu-like illness peaks at days 2–4 and resolves by days 7–10. Productive cough can persist for 2–3 weeks, especially after influenza, without indicating bacterial infection.

Supportive care for viral respiratory illness:

  1. Rest. Reduce physical exertion; the immune response is metabolically expensive.
  2. Hydration. Adults should target at least 2 liters (about 2 quarts) per day; more with fever.
  3. Fever management. Acetaminophen 650–1,000 mg every 6–8 hours for adults (max 4,000 mg/day); or ibuprofen 400 mg every 6–8 hours with food. Do not use ibuprofen in patients with kidney disease, active stomach ulcers, or dehydration. Do not give aspirin to anyone under 18 — Reye syndrome risk.
  4. Honey (1 tablespoon / 15 mL) as a cough suppressant for adults and children over 1 year old. Equal to or better than dextromethorphan by several studies.
  5. Salt water (saline) nasal rinse for congestion. Mix 1/4 teaspoon (1.25 mL) non-iodized salt in 8 oz (240 mL) of warm clean water. Use a neti pot or squeeze bottle.

When viral becomes dangerous: Two patterns convert a viral illness into an emergency: (1) direct viral damage to the lower respiratory tract — influenza pneumonitis, severe COVID — characterized by rapidly falling SpO2 without the bacterial "new fever spike" pattern; and (2) secondary bacterial pneumonia, which arrives after the viral illness has peaked. The sections below address both.

Sources: CDC Antibiotic Use — Outpatient (Tier 1); ATS/IDSA CAP 2019 (Tier 1).

Influenza, COVID, RSV: same triage, different agent

These three cause the most clinically significant viral respiratory illness in adults. Triage proceeds identically — measure SpO2, respiratory rate, temperature, mental status — but antiviral options differ.

Influenza (flu):

When oseltamivir (Tamiflu) is available, start it as soon as possible. The benefit is greatest within 48 hours of symptom onset, but the CDC recommends considering treatment in hospitalized patients or high-risk patients regardless of timing.

  • Adult dose: oseltamivir 75 mg twice daily × 5 days per CDC influenza treatment guidelines.
  • Pediatric weight-based dosing (per CDC): ≤15 kg → 30 mg twice daily; 15–23 kg → 45 mg twice daily; 23–40 kg → 60 mg twice daily; >40 kg → 75 mg twice daily. All doses × 5 days.
  • High-risk populations (age ≥65, pregnancy, immunocompromise, severe obesity, underlying cardiopulmonary disease): treat even if presenting past 48 hours.

COVID-19:

Nirmatrelvir-ritonavir (Paxlovid) and remdesivir (Veklury) are the primary evidence-based antivirals per IDSA COVID-19 Treatment Guidelines. Both require timely initiation and are unlikely to be accessible in a prolonged grid-down scenario. In their absence, treatment is supportive. Apply the same SpO2, respiratory rate, and mental status triage criteria.

RSV in adults:

RSV presents as an upper respiratory infection in most healthy adults — runny nose, congestion, mild cough — and resolves in 1–2 weeks. Older adults, immunocompromised patients, and those with underlying lung disease can develop severe lower respiratory illness. No antiviral is available for outpatient RSV. Supportive care only.

The deceleration phase — recognize it:

Most patients with influenza or COVID-19 improve measurably between days 5–7. A patient who improves and then suddenly gets worse — new fever spike, worsening cough, new chest pain, falling SpO2 — has not had a relapse. They have developed secondary bacterial pneumonia. This pattern is a red flag, not a variation of the original illness. See the dedicated section below.

Pneumonia danger signs: what to measure

Without imaging, pneumonia diagnosis is clinical. Measure all of these, record them, and compare against the thresholds below. A single abnormal finding is a flag; two or more abnormal findings are a probable-pneumonia picture that drives the antibiotic decision.

Finding Normal Abnormal Severe How to measure
SpO2 (pulse oximetry) ≥95% <94% <90% Finger-clip oximeter; wait 30 seconds for stabilization; repeat if movement artifact
Respiratory rate (RR) 12–20/min >24/min >30/min Count chest rises for a full 60 seconds; partial counts multiplied are inaccurate
Temperature 97–99°F (36–37°C) >100.4°F (38°C) >103°F (39.4°C) Digital thermometer; oral is standard; rectal is more accurate for infants
Mental status Alert, oriented Confused, disoriented Unresponsive or AVPU < V Ask: name, date, current location

Pneumonia red flags — any one of these raises bacterial suspicion:

  • SpO2 <94% on room air. Silent hypoxia is the single most dangerous finding — COVID-19 popularized the term because patients maintained normal breathing effort while their oxygen fell into dangerous ranges. Never trust "looks fine" without checking the oximeter. Target SpO2 ≥94%.
  • Respiratory rate >24/min. Measure for a full 60 seconds. Partial measurement multiplied by two significantly overestimates the rate. A rate above 30/min is severe. Normal adult resting rate is 12–20/min.
  • Pleuritic chest pain. Sharp pain that is distinctly worse on deep inspiration or coughing. This localizes inflammation to the pleura (the lung lining) and is a classic pneumonia presentation. Muscle soreness from coughing is diffuse; pleuritic pain is localized and stabbing.
  • Confusion or new altered mental status. In the context of respiratory illness, confusion indicates either severe hypoxia, early sepsis, or both. This is an escalation trigger, not a sign to monitor.
  • Cyanosis. Blue or dusky color of lips, fingernails, or nailbeds. This is a late sign of severe hypoxia. Implies SpO2 is almost certainly below 85%.
  • Fever >100.4°F (38°C) lasting more than 48 hours without improvement. Viral URIs typically produce a fever spike early that begins trending down by days 2–3. Fever that persists or returns after initial improvement raises bacterial suspicion significantly.
  • Productive cough with rust-colored or frankly bloody sputum. Classic for Streptococcus pneumoniae pneumonia. Also seen in Klebsiella pneumonia and pulmonary tuberculosis.
  • Failure to improve by days 5–7 of a viral course. The typical viral URI trend is clear improvement by day 5. A patient still getting worse at this point is on the wrong trajectory.

Sources: ATS/IDSA CAP 2019 — Metlay et al., AJRCCM 200:e45-e67 (Tier 1); WHO Integrated Management of Adolescent and Adult Illness (Tier 1).

Sputum color is unreliable

Green or yellow sputum alone does not indicate bacterial infection and does not justify starting antibiotics.

Both viral and bacterial respiratory infections produce colored sputum. The yellow-green color comes from neutrophil enzymes (myeloperoxidase), not from bacteria. A viral infection with robust immune activation produces exactly the same color as a bacterial infection.

Multiple meta-analyses confirm that sputum purulence has poor predictive value for bacterial infection — with sensitivity around 73% and specificity around 39%, it is only slightly better than a coin flip as a stand-alone diagnostic criterion.

Use the pulse-ox reading, respiratory rate, temperature pattern, and clinical course — not sputum color — to decide whether antibiotics are warranted.

Source: Annals of the American Thoracic Society — Sputum Color as a Marker for Bacteria in COPD, 2022 (Tier 1); European Respiratory Journal — Sputum Color and Bacteria in Chronic Bronchitis Exacerbations, 2012 (Tier 1).

CRB-65 and qSOFA without imaging or labs

These two scoring tools give you a structured severity assessment using only bedside findings — no chest X-ray, no blood work required.

CRB-65 (the field version of CURB-65)

The full CURB-65 score includes a blood urea nitrogen (BUN) lab value. The CRB-65 drops that criterion and works entirely with clinical findings, making it the correct tool for austere settings. One point for each criterion present:

Criterion How to assess Points
C — Confusion New or worsening confusion, disorientation, AVPU < Alert 1
R — Respiratory rate ≥30/min Count for a full 60 seconds 1
B — Blood pressure <90 systolic OR diastolic ≤60 BP cuff if available; use shock signs (rapid weak pulse, capillary refill >2 seconds, pallor) if no cuff 1
65 — Age ≥65 years Self-evident 1

Interpretation:

  • Score 0: Outpatient management appropriate — low mortality risk. Monitor for deterioration.
  • Score 1–2: Consider hospital-equivalent care or evacuation. Increased risk. Closely monitor SpO2 and RR every 4–6 hours.
  • Score ≥3: Severe pneumonia. High mortality without hospital-level care. Aggressive intervention warranted; evacuation priority.

qSOFA — sepsis alert

qSOFA (quick Sequential Organ Failure Assessment) is the same tool used on the wound infection and sepsis page. Apply it here when respiratory illness has progressed to possible sepsis. One point each for:

  • Altered mental status
  • Respiratory rate ≥22/min
  • Systolic blood pressure ≤100 mm Hg

A qSOFA score of ≥2 = probable sepsis. This is an evacuation emergency regardless of antibiotic status. Do not use qSOFA as a primary tool for pneumonia severity — use CRB-65 for that. Use qSOFA when you suspect the infection has gone systemic.

Sources: ATS/IDSA CAP 2019 (Tier 1); Sepsis-3 — Singer et al., JAMA 2016 (Tier 1).

Empiric antibiotics for community-acquired pneumonia: when justified

Empiric antibiotics for respiratory illness are warranted only when the clinical picture is consistent with bacterial pneumonia — not for every fever, not for every cough, not because the sputum is colored. The decision gate is the combination of danger signs described above plus the absence of an escalation option.

Start empiric antibiotics when ALL of the following apply:

  1. Clinical picture is consistent with pneumonia (two or more danger signs from the table above, OR one severe sign such as SpO2 <90% or confusion)
  2. No hospital or higher-level care is accessible
  3. Patient has no documented allergy to the antibiotic class

Antibiotic selection

Clinical scenario First choice Alternative Duration
Adult, no significant comorbidities, no antibiotics in past 3 months Amoxicillin 1 g three times daily Doxycycline 100 mg twice daily (penicillin allergy; also covers atypicals) 5 days
Adult, with comorbidities (chronic heart/lung/kidney/liver disease, diabetes, immunosuppression, recent antibiotics) Amoxicillin-clavulanate 875/125 mg twice daily + azithromycin 500 mg day 1 then 250 mg days 2–5 Levofloxacin 750 mg once daily × 5 days (respiratory fluoroquinolone; avoid if known QT prolongation or seizure history) 5 days
Pediatric (>3 months), presumed pneumococcal Amoxicillin 90 mg/kg/day divided twice daily (max 4 g/day) Azithromycin 10 mg/kg day 1 (max 500 mg), then 5 mg/kg days 2–5 (max 250 mg), if atypical suspected 5 days
Aspiration suspected (witnessed aspiration, dental disease, decreased consciousness, alcohol use) Amoxicillin-clavulanate 875/125 mg twice daily Clindamycin 600 mg three times daily 5–7 days
Influenza-related secondary bacterial (see deceleration section below) Amoxicillin-clavulanate 875/125 mg twice daily OR doxycycline 100 mg twice daily TMP-SMX 800/160 mg twice daily added if MRSA suspected (necrotizing pattern, hemoptysis, rapid deterioration) 5–7 days

Notes on azithromycin (Z-pack): The 2019 ATS/IDSA guideline removed azithromycin from its first-line recommendation for outpatient CAP without comorbidities due to rising macrolide resistance in Streptococcus pneumoniae (the most common bacterial cause of CAP). Azithromycin is still useful as combination therapy in the comorbidity scenario and in pediatric atypical pneumonia (Mycoplasma pneumoniae, Chlamydia pneumoniae). Do not rely on azithromycin monotherapy as primary CAP coverage where macrolide resistance is prevalent.

Reassess at 48–72 hours. If the patient is clearly improving — fever trending down, SpO2 stable or improving, respiratory rate decreasing, less fatigue — continue to the 5-day minimum. If the patient is not improving or is worsening at 48 hours, re-examine: is this the right antibiotic for the likely organism? Is there an unrecognized aspiration component? Has the patient developed respiratory failure (see below)?

Stop early? Only if the patient develops a clear allergic reaction (rash, hives, throat tightening) — then stop immediately and treat the allergy. Never stop because the patient "feels better" before completing 5 days. The bacteria that remain when symptoms resolve are the ones that generate resistance.

Sources: ATS/IDSA CAP 2019 — Metlay et al., AJRCCM 200:e45-e67 (Tier 1); PIDS/IDSA Pediatric CAP 2011 — Bradley et al., CID 53:e25-e76 (Tier 1).

Secondary bacterial after viral: the deceleration trap

The most commonly missed respiratory emergency is the patient who is getting better and then suddenly gets worse. This is not a viral relapse — it is a new infection piggybacking on lung tissue that has already been damaged by the virus.

The pattern:

  • Patient has influenza, COVID, or a significant URI.
  • Days 2–5: illness peaks, patient appears to be improving.
  • Days 5–10: patient develops a new fever spike (often higher than the initial viral fever), new focal chest pain (usually one-sided and pleuritic), new or worsening productive cough, or a drop in SpO2 that was previously stable.

This interval — improvement followed by sudden decline — is the classic presentation of secondary bacterial pneumonia. Missing it and attributing the worsening to "the flu getting worse" is a common and lethal error.

Why this happens:

Influenza and other respiratory viruses damage the epithelial lining of the lower airways, suppress neutrophil function, and impair the mechanical clearance of bacteria from the lung surface. Bacteria that were previously contained on airway surfaces — especially Streptococcus pneumoniae, Staphylococcus aureus (including MRSA strains), and Haemophilus influenzae — find an open door into compromised lung tissue.

Most common pathogens after influenza: S. pneumoniae (most common), S. aureus including MRSA (most dangerous, can cause necrotizing pneumonia), H. influenzae.

Warning signs specific to MRSA-associated pneumonia:

  • Hemoptysis (coughing blood) in the context of post-influenza deterioration
  • Rapidly progressive respiratory distress over 12–24 hours
  • Necrotizing pattern on imaging (unavailable in field, but symptom severity is a clinical surrogate)

If MRSA-associated necrotizing pneumonia is suspected: add TMP-SMX 800/160 mg twice daily to the base regimen and escalate immediately.

Treatment: Start empiric antibiotics as bacterial pneumonia (amoxicillin-clavulanate or doxycycline as first line; see table above). Escalate as a high-priority case — secondary bacterial pneumonia after influenza carries higher mortality than either infection alone.

Source: Secondary Bacterial Infections in Patients With Viral Pneumonia — Manohar et al., PMC 2020 (Tier 1, peer-reviewed); CDC Seasonal Flu HCP Clinical Guidance (Tier 1).

Respiratory failure: when there is no escalation

Respiratory failure in an austere setting is one of the hardest situations this manual addresses. It requires honesty about what is possible and what is not.

Defining respiratory failure in this context:

  • SpO2 <90% on room air despite supportive positioning and care
  • Respiratory rate >30/min sustained over 30+ minutes
  • Accessory muscle use: the patient is using neck, shoulder, and upper chest muscles to breathe (you can see them straining)
  • Paradoxical breathing: the abdomen moves outward while the chest moves inward on inspiration — the opposite of normal
  • Cyanosis of lips or nailbeds

At this level of compromise, the patient needs supplemental oxygen, positive-pressure ventilation, or both. In most household and field scenarios, those are not available.

What you can do:

1. Prone positioning (awake proning)

Have the patient lie face-down for sessions of 30 minutes on, then 30 minutes in another position (side-lying or semi-reclined), cycling throughout the day. Awake prone positioning was studied extensively during the COVID-19 pandemic and showed consistent improvement in oxygenation in non-intubated patients with hypoxic respiratory failure — through a mechanism of opening atelectatic lung regions in the posterior lung zones that are preferentially affected in severe viral pneumonia.

This is not a cure. It is a temporizing measure that may improve SpO2 by 3–6 percentage points in some patients and may reduce the drive to breathe against impaired lungs. It is worth attempting while evacuation is arranged.

2. Head of bed elevated 30–45°

Never lie a respiratory failure patient flat. Head elevation reduces the work of breathing and improves functional residual lung capacity. This is one of the simplest and most impactful positioning interventions available without any equipment.

3. Pursed-lip breathing coaching

Instruct the patient to breathe in through the nose for 2 counts, then exhale slowly through pursed lips for 4 counts. This technique — well established in COPD management — slows respiratory rate, reduces air trapping, and reduces the sense of air hunger. A patient who is panicking and breathing at 35/min may slow to 24/min with effective pursed-lip coaching.

4. Hydration without fluid overload

Maintain at least 1.5–2 liters (about 1.5–2 quarts) per day for an adult patient in respiratory failure. Dehydration worsens mucus viscosity and impairs expectoration. However, fluid overload worsens pulmonary edema — if the patient has underlying heart failure or you can see leg swelling and hear gurgling breaths, restrict fluids.

5. Supplemental oxygen

If supplemental oxygen is available (a rare but meaningful preparedness advantage for any household with a chronically ill member), target SpO2 ≥90–94%. Titrate to the lowest flow rate that maintains that target. See chronic conditions preparedness for oxygen concentrator sizing and stockpiling.

When there is no escalation option:

This is the hardest paragraph on this page to write. If the patient is in respiratory failure and no hospital is reachable, the medically honest answer is that most interventions available in a household setting are insufficient to reverse severe hypoxic respiratory failure. The goal shifts to:

  • Comfort: position the patient to minimize air hunger; use acetaminophen for fever; reduce anxiety with calm presence and verbal reassurance
  • Dyspnea: if opioid analgesics are in the household (see long-term medication strategy), low-dose morphine reduces the subjective sensation of air hunger and reduces the respiratory drive without worsening outcome in a patient already in respiratory failure
  • Family preparation: tell the family what is happening. Prepare them for the possibility that the patient may not recover. Time together with the family present, mental health support, and preparation for a comfortable death are legitimate medical goals when cure is not possible

This is not giving up — it is the correct and compassionate reframing of goals when escalation is impossible.

Outbreak control: isolation in a household

One respiratory illness in a household is a case. Without isolation, it becomes an outbreak. The window to prevent spread is the first few hours of symptoms.

Immediate isolation setup

  1. Assign the sick person to a single room with a closing door. A room with its own bathroom is ideal. If not, the patient uses the bathroom last, and it is cleaned after every use before other household members enter.

  2. Place a box fan or window fan facing outward in the sick room window. Air is exhausted from the sick room to the outside, creating a mild negative-pressure effect that draws household air into the sick room rather than sick-room air into the household. Seal the gap under the door with a rolled towel when the fan runs.

  3. Mask the sick person when the caregiver enters. A surgical mask worn by the source patient — not just by the caregiver — is one of the most effective single interventions to reduce respiratory droplet spread.

  4. The caregiver wears a mask. An N95 or KN95 respirator provides the best protection. A surgical or cloth mask is meaningfully better than nothing. Assign one caregiver to the sick room; do not rotate multiple household members through the role. Each additional person who enters the sick room multiplies household exposure.

  5. Hand hygiene between every contact. Soap and water for 20 seconds. Respiratory droplets settle on hands and surfaces. The hand-to-face route is significant for most respiratory pathogens.

  6. Surface decontamination. Mix 4 teaspoons (about 20 mL) of household bleach per quart (about 1 liter) of water — approximately a 1:10 dilution of 5.25% sodium hypochlorite, yielding roughly 5,000 ppm chlorine. Apply to doorknobs, light switches, faucet handles, toilet handles, and shared contact surfaces daily. Allow 1 minute of contact before wiping.

  7. Cohort sleep. During an active outbreak, the sick person should not share a bed or bedroom with other household members. Respiratory transmission during sleep, when people are in close proximity for hours, is a major pathway.

For the complete donning and doffing sequence for N95 + gown + eye protection, and the full isolation room supply list for longer-duration infectious illness, see pandemic preparedness. That page covers a longer-duration respiratory illness scenario with a complete PPE protocol, symptom monitoring schedule, and multi-week supply requirements.

Field note

The sick person wearing a surgical mask is approximately as protective as — and in some studies more protective than — the caregiver wearing one. If you only have one mask, put it on the sick person, not the caregiver. This runs counter to instinct but is well-supported by transmission research.

Pediatric and pregnancy red flags

Respiratory illness in children and pregnant patients requires lower escalation thresholds than healthy adults.

Neonates and young infants

  • Any neonate (<28 days): Any fever ≥100.4°F (38°C) rectal, any respiratory distress (grunting, nasal flaring, retractions, RR >60/min), or any change in feeding pattern = emergency room, no exceptions. Neonates cannot mount a typical immune response and deteriorate faster than any other population. Per AAP 2022 guidelines.
  • Infants 1–3 months: Fever ≥100.4°F (38°C) rectal requires same-day medical evaluation. Respiratory rate >60/min, retractions, or poor feeding = emergency evaluation.

WHO respiratory rate thresholds for children

The WHO age-specific respiratory rate thresholds identify pneumonia in children more reliably than adult thresholds:

Age Tachypnea threshold Action
< 2 months ≥60 breaths/min Emergency
2–12 months ≥50 breaths/min Urgent evaluation
1–5 years ≥40 breaths/min Urgent evaluation
>5 years ≥30 breaths/min (or adult threshold of >24/min for CAP suspicion) Concerning

For any infant or child with respiratory illness, also see infant and toddler care for age-specific fever decision tables and hydration thresholds.

Pregnancy

  • Respiratory illness baseline is altered in pregnancy: the growing uterus elevates the diaphragm, reducing functional residual capacity by up to 20%. What looks like normal breathing work in a non-pregnant person may represent significant compromise in a pregnant patient.
  • Target SpO2 ≥95% in pregnancy (one point higher than the non-pregnant adult threshold). SpO2 <95% in a pregnant patient warrants the same urgency as SpO2 <90% in a non-pregnant adult.
  • Influenza in pregnancy carries higher complication risk. Per ACOG, antiviral treatment (oseltamivir) should be started early and at lower threshold in pregnant patients — do not wait for 48-hour confirmation before treating.
  • Avoid ibuprofen and other NSAIDs from 20 weeks of pregnancy onward per FDA 2020 drug safety communication (low amniotic fluid risk from 20 weeks; premature closure of the fetal ductus arteriosus risk rises sharply from ~30 weeks onward). Acetaminophen is the preferred antipyretic throughout pregnancy.

Asthma and COPD baseline

A respiratory illness exacerbation in a patient with pre-existing asthma or COPD can mask superimposed pneumonia. Apply a lower threshold for empiric antibiotics if the clinical picture changes character — new fever after several days, new chest pain, new SpO2 drop outside the patient's typical exacerbation pattern. What looks like a routine asthma flare may be both.

Common mistakes that get people killed

These are the errors that appear consistently in austere-environment case reports and disaster medicine literature. Read them before you are in the situation.

Starting antibiotics for every cough or fever. Most respiratory illness is viral. Every unnecessary antibiotic course disrupts gut flora, creates resistance risk, and depletes a supply that may not be replaceable. The decision criteria above exist precisely to separate the minority who need antibiotics from the majority who do not.

Trusting sputum color as the antibiotic trigger. Green or yellow sputum does not indicate bacterial infection. Both viral and bacterial illness produce colored sputum through the same neutrophil enzyme mechanism. Using this as the primary decision criterion leads to antibiotic overuse. Use SpO2, RR, fever pattern, and the danger-sign checklist.

Skipping the pulse oximeter on "looks fine" patients. Silent hypoxia is a documented phenomenon — particularly with COVID-19 and some influenza pneumonia presentations. A patient can have SpO2 of 88% and appear minimally distressed. Never make a severity judgment without measuring SpO2 directly.

Missing the deceleration trap. The patient who gets better and then suddenly worsens is developing secondary bacterial pneumonia, not having a viral relapse. This pattern demands an antibiotic decision, not "let's watch it another day."

Lying the patient flat. Supine positioning worsens oxygenation in any respiratory illness. The standard should be head of bed elevated 30–45° at all times, with prone positioning for sessions during severe illness. Flat is never the right position for a patient with respiratory distress.

Treating an asthma exacerbation as purely asthma when pneumonia underlies it. Patients with asthma or COPD may present an exacerbation that masks superimposed pneumonia. If the exacerbation does not respond to bronchodilators and supportive care within 24–48 hours, or if the character of the illness changes (new fever, new pleuritic pain), reassess for pneumonia.

Stopping antibiotics at 48 hours because the patient feels better. Antibiotic effectiveness begins before symptoms fully clear. Stopping at first symptomatic improvement leaves residual bacteria that are more likely to be resistant and more likely to relapse. Complete the 5-day minimum course unless allergy occurs.

Failing to isolate. Influenza spreads most efficiently in the first 2–4 days of illness. RSV and other respiratory viruses spread via droplets deposited on surfaces. A single symptomatic person sharing meals, a bathroom, and a sleeping area with four other people will infect the household within days in most scenarios. One sick room, one door, one caregiver.

Teach your family

Seven plain-language rules that every household member should know before an outbreak occurs:

  1. Check the pulse oximeter once a day on any sick person. Below 94% = wake the adult in charge immediately. Below 90% = this is an emergency. Do not wait for other symptoms to appear.

  2. Count breaths for a full minute — not 15 or 30 seconds. On a resting adult: more than 24 breaths per minute is concerning. More than 30 is serious. On a child under 5: more than 40 is concerning.

  3. Cover coughs with the inside of the elbow, not the hand. Hands touch everything; elbows touch nothing. Teach children this habit before they need it.

  4. Sit up, don't lie flat. Any sick person with a cough or breathing difficulty should be sitting or lying with the head elevated. Flat position makes breathing harder.

  5. One sick room, door closed, caregiver wears the mask. The sick person also wears a surgical mask when the caregiver is in the room. This is the single most impactful household intervention.

  6. Do not ask for antibiotics for a cold. Viral illness does not respond to antibiotics. Giving amoxicillin for a sore throat caused by a virus does nothing and depletes a supply you may genuinely need later. The threshold is SpO2 <94%, RR >24, and a pneumonia danger sign — not "feels awful."

  7. New fever after getting better = red flag. A patient improving from flu who suddenly spikes a fever again, develops chest pain, or starts breathing fast has likely developed a secondary bacterial pneumonia. That pattern changes the urgency level immediately — wake the adult in charge.

Every page in this section addresses a different aspect of the respiratory illness triage and management framework:

Sources and next steps

Last reviewed: 2026-05-22

Source hierarchy:

  1. ATS/IDSA Community-Acquired Pneumonia Guidelines 2019 — Metlay et al., AJRCCM 200:e45-e67 (Tier 1, professional medical society guideline)
  2. PIDS/IDSA Pediatric Community-Acquired Pneumonia Guidelines 2011 — Bradley et al., CID 53:e25-e76 (Tier 1, professional medical society guideline)
  3. CDC Treating Flu with Antiviral Drugs — oseltamivir dosing (Tier 1, federal public health agency)
  4. CDC Antibiotic Use — Adult Outpatient Clinical Care (Tier 1, federal public health agency)
  5. Sepsis-3 Definition — Singer et al., JAMA 2016 (Tier 1, peer-reviewed clinical standard)
  6. WHO Pulse Oximetry Training Manual 2011 (Tier 1, international health authority)
  7. WHO Integrated Management of Childhood Illness (IMCI) (Tier 1, international health authority — pediatric RR thresholds)
  8. Secondary Bacterial Infections in Patients With Viral Pneumonia — PMC 2020 (Tier 1, peer-reviewed)
  9. Awake Prone Positioning in COVID-19 — PMC 2024 meta-analysis (Tier 1, peer-reviewed)

Legal/regional caveats: Antibiotic prescribing authority varies by jurisdiction — in most US states, prescription antibiotics require a licensed prescriber. This page describes antibiotic selection for emergency preparedness education only. Fluoroquinolone use (levofloxacin) carries documented risks including tendinopathy and QT prolongation — use only when alternatives are contraindicated. Pediatric dosing should be verified by a licensed provider whenever possible. Oseltamivir and antiviral medications require a prescription in the US; stockpiling decisions should be made with a physician's guidance.

Safety stakes: life-safety topic — verify against current local/professional guidance before acting.

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