General Wellness
Carbon Monoxide, Blood Test Blood Test Preparation Guide
- Blood draw
- General Wellness
- Prep checklist included
At a glance
Carbon Monoxide, Blood Test Blood Test: prep snapshot
- Sample type
- Blood draw
- Fasting
- Fasting is usually not required for this test, but some labs may have specific instructions…
- Best collection time
- Because carbon monoxide leaves the blood over time, collect the sample as soon as possible…
- Typical turnaround
- Varies by collection lab
- Category
- General Wellness
This page explains how to prepare for a Carbon Monoxide, Blood Test, what the test measures, and what to confirm with the collection lab. A carbon monoxide blood test measures the level of carbon monoxide bound to hemoglobin in your blood.
What the results reflect
The test measures the percentage of hemoglobin that is bound to carbon monoxide rather than oxygen. It can help show whether a recent exposure has occurred and how significant that exposure may be.
- Carboxyhemoglobin
- Carbon monoxide level
- Hemoglobin
Getting ready for the Carbon Monoxide, Blood Test
Routine orders for this test rarely require special preparation. The collection lab can confirm any timing, fasting, or appointment details when you book.
- Book your appointment at a local collection lab and ask whether fasting or timing instructions apply.
- Tell the staff about recent exposure to smoke, exhaust, fumes, or any known carbon monoxide source.
- Avoid smoking or other combustion exposure right before the draw if the lab advises it, since recent exposure can affect results.
- Bring a list of your current medications and supplements to the appointment.
- Wear a short-sleeved shirt or top that allows easy access to a vein for the blood draw.
Fasting, timing, sample type, and what to bring
Fasting
Fasting is usually not required for this test, but some labs may have specific instructions based on your situation. Confirm with your lab before your appointment.
Best time to collect
Because carbon monoxide leaves the blood over time, collect the sample as soon as possible after a suspected exposure or when symptoms are present. Your clinician or the lab can advise on the best timing for your situation.
Sample type
Blood draw. The collector will explain the process before starting.
What to bring
- Your order confirmation email, in case the collection site asks to see it
- Your printed lab order or requisition form — the ordering physician prepares it for you after you order, and you print it (or fax it from your account) before visiting
- A short-sleeved or loose-sleeved shirt for an easy blood draw
- Water to drink before the draw and a light snack for afterward, if your test requires fasting
- A government-issued photo ID (most collection sites verify identity at check-in)
- A written list of the medications and supplements you currently take
You do not need an insurance card or a payment method at the collection site: the lab does not bill insurance, and you pay at order time, so there is no copay or deductible. The lab also provides the physician's requisition, so you do not need a separate doctor's referral.
Order process and what-to-bring details reflect the lab's published instructions, paraphrased in our own words. Confirm final requirements with the collection lab that will perform your draw.
At the collection site
A healthcare professional draws a small sample of blood from a vein in your arm, usually in less than a few minutes. The sample is then sent to a laboratory for analysis, and you can return to your normal activities afterward.
Details worth confirming with the collection lab before your visit:
- Does this test require fasting or any timing restrictions?
- How soon after a suspected exposure should I collect the sample?
- Will recent smoking or smoke exposure affect my results?
Why a clinician may order this test
A clinician may order this test when you have symptoms such as headache, dizziness, nausea, or confusion that could be related to carbon monoxide exposure. It may also be used to monitor known exposure in certain work or home environments.
Understanding your results
Reference ranges for carboxyhemoglobin can vary between laboratories and may depend on smoking status and other factors. Your lab report will include the range used for your sample, and your clinician will interpret the result in context.
General test information is compiled from publicly available reference material, including MedlinePlus (medlineplus.gov) and the Centers for Disease Control and Prevention (cdc.gov), and is reviewed for clarity. Preparation and what-to-bring details reflect the lab's published instructions, paraphrased into our own words. Preparation instructions, timing, and pricing vary by collection lab — always confirm them with the lab that will perform your draw.
Common questions
Frequently asked questions
Do I need to fast for a carbon monoxide blood test?
Fasting is usually not required, but your collection lab can confirm whether any restrictions apply to your order.
How long does it take to get results?
Results are typically available within one to three business days after the sample is collected.
Can smoking affect the results?
Yes, smoking and other recent combustion exposure can raise carbon monoxide levels, so tell the lab about any recent exposure.
Where can I get this test done?
You can order the test online through a partner and visit a local collection lab near you for the blood draw.