Hair Drug Test Collection: How Much Hair Is Really Needed?
If you’ve been scheduled for a hair follicle drug test, you might be wondering just how much hair is actually cut, and whether you’ll leave the test site with a noticeable bald spot.
The good news? Hair drug testing is a precise, minimally invasive process that won’t ruin your haircut or dating life when performed by a trained professional.
What Is a Hair Follicle Drug Test and How Does It Work?
A hair drug test screens for drug use by analyzing a small hair sample for drug metabolites. These substances remain trapped in the hair shaft and can reveal drug use for up to 90 days.
During collection, a technician will trim a small amount of hair from the crown of the back of your head, where the removal is less noticeable. The sample is then sealed and sent to the lab for testing.
This type of test is commonly used in workplace drug testing programs, legal proceedings, and situations where a long-term drug use history is relevant.
Hair follicle tests can detect a range of substances, including:
- Marijuana
- Amphetamines, including methamphetamine and MDMA (ecstasy)
- Cocaine
- Opiates, such as heroin, codeine, and morphine
- Phencyclidine (PCP)
How Much Hair Is Needed for a Hair Drug Test?
For most hair follicle drug screenings, labs require about 100 milligrams of hair, taken from the first 1.5 inches closest to the scalp. Because hair texture and thickness vary, collectors follow visual guidelines:
- If your hair is over 4 inches long: Approximately 120 strands, or the width of a pencil when bundled, or about 1 centimeter wide when laid flat.
- For shorter hair (½ inch to 4 inches): More strands are collected to ensure there’s enough material for accurate testing.
- Curly or coiled hair: Should resemble the size of a cotton ball, and root alignment is not required.
Collectors ensure the root ends are aligned properly in the testing foil for optimal lab processing.
What If You Have Short or No Scalp Hair?
If your head hair is less than ½ inch long or nonexistent, the test can still be performed using body hair. Collectors will take hair from the:
- Chest
- Underarms
- Legs
- Face
The sample must still meet the required quantity- roughly the size of a standard cotton ball. Collectors also record the source of the sample, as body hair grows more slowly and may reflect a longer detection period.
Can You Prepare or Wash Your Hair Before a Drug Test?
You do not need to take any special steps to prepare for a hair drug test. Simply continue with your normal hair care routine. Shampooing, conditioning, or styling your hair won’t affect test results- drug metabolites reside inside the hair shaft and aren’t removed with washing.
Do Hair Drug Tests Take a Lot of Hair?
Absolutely not. One of the most common hair drug test myths is that you’ll walk away with a visible bald patch. In reality, trained collectors only take what’s needed- usually a small, hidden section that’s barely noticeable.
Key Takeaways: Hair Drug Test Collection Facts
- Only a small sample of hair is required- typically 100 milligrams or 120 strands
- Hair is taken from the crown to keep the cut discreet
- Body hair can be used if scalp hair is too short
- No need to alter your hair care routine before the test
- Hair drug testing can detect use for up to 90 days
Whether you’re an employer requiring a hair drug screening or an individual preparing for one, it’s important to know the facts. With standardized procedures and expert collectors, the hair sample collection process is simple, safe, and stress-free.