CO Symptoms Action Check

WARNING: If you are currently experiencing severe symptoms - confusion, difficulty walking, chest pain, loss of consciousness - or if your CO alarm is sounding, leave the building immediately and call 911. Do not continue with this action check first.

Carbon monoxide symptoms often overlap with the flu, food poisoning, altitude sickness, and migraine. Headache, nausea, dizziness, and fatigue are common to all of them. The key difference is context: Do symptoms improve when you leave the building? Are multiple people or pets affected at the same time?

This 1-minute action check asks five questions about symptoms, exposure context, and who else is affected. It helps you decide whether to leave now, call 911, call Poison Control, or keep monitoring while you investigate the source.

This is not a diagnosis tool. It is a safety action tool. When in doubt, leave the building and call 911. Carbon monoxide exposure can escalate quickly.

In 60 Seconds

• CO symptoms often mimic the flu: headache, nausea, dizziness, fatigue, and confusion.
• The strongest clue is context: symptoms improve outside, multiple people feel sick, and pets may also act unwell.
• Children, older adults, pregnant individuals, and people with heart or lung conditions can be affected faster and at lower concentrations.
• Even mild symptoms deserve prompt safety action and medical follow-up when appropriate.
• When in doubt, get out. Leave the building, call 911 from outside, and do not re-enter until responders clear it.

What This Check Covers

• What symptoms are happening right now and whether any are severe.
• Whether symptoms improve when you leave the building.
• Whether multiple people or pets in the same location are affected.
• Whether a likely CO source is nearby.
• Whether anyone affected is in a vulnerable group.

Start the Check

How to Interpret Your Result

This action check routes symptom-and-exposure patterns to the safest next step using CDC, CPSC, Poison Control, and clinical reference guidance.

• Monitor Symptoms and Check the Environment:Your answers do not strongly match the classic CO exposure pattern. Monitor your symptoms, verify that CO detectors are working, and call Poison Control or your doctor if symptoms persist.
• Leave and Get Guidance Now:Your symptoms and context are consistent with possible carbon monoxide exposure. Leave the building, call Poison Control, and do not re-enter until the building has been checked.
• Leave Now and Call 911:Your symptoms and context strongly suggest a dangerous exposure pattern. Leave immediately, call 911 from outside, and go to the nearest emergency room.

Sources & References

1. CDC — CO Poisoning Basics. ~400 deaths/year, 100,000+ ER visits, symptoms, prevention.
2. CDC — Clinical Guidance for CO Poisoning. Treatment protocols, COHb interpretation.
3. CPSC — CO Questions and Answers. PPM symptom thresholds, alarm standards.
4. Mayo Clinic — Carbon Monoxide Poisoning. Symptoms, when to see a doctor, causes, prevention.
5. Cleveland Clinic — Carbon Monoxide Poisoning. Severity staging and emergency warning signs.
6. StatPearls/NCBI — Carbon Monoxide Toxicity. Symptom percentages, COHb thresholds, delayed neurological sequelae.
7. Johns Hopkins Medicine — Carbon Monoxide Poisoning. Flu vs CO differentiation.
8. OSHA — CO Effects at Different Concentrations. Official concentration and time-to-effect chart.
9. AAP — Carbon Monoxide Exposure. Pediatric-specific susceptibility.
10. Poison Control — Carbon Monoxide Poisoning. Emergency guidance, 1-800-222-1222.