Carbon Monoxide, Blood Test
This page explains the carbon monoxide, blood test, what it measures, and how to arrange it. A carbon monoxide (CO) blood test measures how much CO is attached to hemoglobin, the protein that carries oxygen in your blood. It is ordered when someone has symptoms like headache, dizziness, or confusion that might be from smoke, car exhaust, or faulty heaters, or to check exposure in certain jobs.
- Sample type
- blood
- Category
- General Wellness
- Turnaround
- 1-3 business days
- Price
- $179
- Referral
- Not required
A carbon monoxide (CO) blood test measures how much CO is attached to hemoglobin, the protein that carries oxygen in your blood. It is ordered when someone has symptoms like headache, dizziness, or confusion that might be from smoke, car exhaust, or faulty heaters, or to check exposure in certain jobs.
What it measures
- Carboxyhemoglobin (COHb) — The percentage of hemoglobin carrying carbon monoxide instead of oxygen.
- Hemoglobin (Hb) — The total amount of oxygen-carrying protein in your blood.
- Oxygen saturation (SaO2) — How much oxygen is attached to hemoglobin, often measured alongside COHb.
- Methemoglobin (MetHb) — A form of hemoglobin that cannot carry oxygen; sometimes checked to rule out other causes.
Who it is for
A doctor may order this test if you have unexplained symptoms of CO exposure, such as headache, nausea, or confusion, especially if others in the same building have similar symptoms. It is also used for people who work with combustion engines, furnaces, or in firefighting.
Preparation
No fasting or special preparation is needed. Tell your doctor if you smoke, because smoking can raise your baseline CO level.
Results and what they mean
Results are reported as a percentage of carboxyhemoglobin. Normal levels are usually low, but interpretation depends on whether you smoke and your symptoms. Only a clinician can interpret your results in context; this information is not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the carbon monoxide, blood test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Does this test hurt?
It uses a standard blood draw from a vein, which feels like a quick pinch.
How long do results take?
Most results are ready in 1 to 3 business days.
Can I eat before the test?
Yes, no fasting is required.
Is my result kept private?
Yes, your results are confidential and shared only with you and your healthcare team.