Carbon monoxide (CO) is a gas you can’t see, smell, or taste. It comes from things like gas stoves, heaters, furnaces, and car engines. When it builds up indoors, it poisons you — and the scary part is that it feels almost identical to the flu at first. We’re talking headache, dizziness, weakness, nausea, vomiting, rapid heartbeat, and shortness of breath. Research published in medical literature confirms that subacute carbon monoxide poisoning is commonly misdiagnosed as a flu-like viral illness — meaning even medical professionals can miss it.
According to the CDC, more than 400 Americans die every year from unintentional CO poisoning not linked to fires. That’s not a rare freak accident. That’s a steady, preventable number of people who likely thought they were just sick. The NCBI notes that symptoms are ‘nonspecific,’ which is a medical way of saying they look like a dozen other things — which is exactly why it’s so dangerous. Some people are at higher risk, including infants, the elderly, and people with chronic heart disease, anemia, or breathing problems.
Here’s the key thing to watch for: if multiple people in the same house feel sick at the same time, or if you feel noticeably better when you go outside, take that seriously. Those are red flags that it might not be a regular illness. Johns Hopkins lists symptoms that can escalate to seizures, chest pain, disorientation, and loss of consciousness — so this isn’t something that just stays mild.
What you should actually do: Get everyone out of the building immediately. Don’t stop to grab things. Call 911 from outside. Don’t go back in until emergency responders say it’s safe. Long-term, having a working CO detector in your home — especially near sleeping areas — is one of the simplest ways to protect yourself and your family.
The single most important thing to remember: if you feel flu-like symptoms that seem to get better when you leave your home or building, treat it as a possible CO emergency until proven otherwise. Getting outside fast is free. Staying inside to ‘wait and see’ can kill you.