An at-home breath test measures the gases you exhale before and after drinking a special substrate drink. You follow a strict prep diet the day before, fast overnight, collect a starting breath sample, drink the substrate, then collect timed breath samples over the next 2–3 hours. Preparation is the most critical part — diet errors and missed medication pauses are the primary cause of invalid results that require recollection.
Important: Register your kit before you start. If you skip the prep diet or fasting steps, your results will be invalid and you will need to collect again.
The day before: prep diet
For the full 24 hours before your test, eat only these foods:
Plain baked, broiled, or boiled chicken, fish, or turkey — seasoned with salt only, no marinades, sauces, or other seasonings
Plain white rice — no butter, oil, or sauce
Plain eggs — no milk, oil, or seasoning
Plain water
Avoid everything else during this 24-hour period, including all fruits and vegetables and their juices, bread, pasta, cereal, oats, grains, dairy products, beans and legumes, nuts and seeds, alcohol, carbonated drinks, gum, mints, candy, sugar, and sweeteners of any kind.
Overnight: Fast before the test
After your prep-diet dinner, begin a complete fast. Do not eat or drink anything except plain water for at least 12 hours before the test starts.
Important: Some medications must be paused well in advance of the test.
Antibiotics and oral antifungal medications: pause for up to 4 weeks before the test
Probiotics: pause for several days before the test
Laxatives and fiber supplements: pause for about 24 hours before the test
Follow your kit's specific timing for each medication. Never stop a prescribed medication without first talking to your care provider. If you have recently taken antibiotics, contact your care provider to reschedule before you begin.
Morning of the test
On the morning of your test, before you begin:
Do not eat, drink (except water), smoke, exercise, or sleep in.
Do not brush your teeth with toothpaste or use mouthwash. Both can produce gases that interfere with test results.
Set up your kit in a place where you can stay for the full 2–3 hour collection period.
Collecting the breath samples
The table below summarizes each step in the collection process.
Step | What to do |
Baseline (0 minutes) | Hold your breath for 30 seconds, then exhale slowly and completely into the labeled tube |
Drink the substrate | Immediately after the baseline sample, mix the substrate powder with 4–6 oz of plain water and drink it all within 5 minutes |
Timed samples | Collect one breath sample on your kit's schedule — commonly every 20 minutes for 2–3 hours |
For each timed breath sample:
Hold your breath for 30 seconds.
Exhale slowly and completely into the collection tube.
Label the tube with the time point (for example, "20 minutes") and the actual clock time of collection.
Do not eat, drink anything except plain water, exercise, or sleep during the collection period.
Note: If you burp into a tube, discard that tube and use a backup from your kit. Some bloating or gas after drinking the substrate is normal.
After all samples are collected
Place all tubes in the prepaid shipping box and ship the same day. Breath samples are stable at room temperature and do not require a cold pack.
Need more help?
If you ate something outside the prep diet, are unsure about medication timing, or need to reschedule, contact our support team through chat with your Kit ID before you begin the test. There is no cost for a replacement collection kit when a new sample collection is needed for the lab to complete your analysis.