What Is a Hair Analysis Test?

Medically Reviewed by Nayana Ambardekar, MD on March 31, 2024
3 min read

A single hair can give a lot of information about you. The hair on your head grows 2-6 years before falling out. Many tiny blood vessels feed the base of each strand. During that time, your hair shaft absorbs chemicals from any drugs you take. It also contains sweat, your body’s natural oils, and any toxins around you.

A hair analysis uses special techniques to look closely at your hair under a microscope. The results can show details about your health and habits. Different labs do the tests differently, and their results can vary a lot. Experts say hair analysis is most helpful when paired with tests that use something other than hair.

Drug use: As your hair grows, some drugs will “stick” to the strands. You can’t wash them out. Because of that, your hair can reveal if you’ve been using drugs like opioids, cocaine, amphetamines, and cannabis. While a urine test will reveal if you’ve used drugs in the last several days, hair testing can show if you’ve done drugs over the past 3 months.

Heavy metals: If your hair has toxins like mercury and arsenic, you could be more likely to get certain health problems.

Some genetic disorders: For example, a hair sample can help diagnose Fragile X syndrome. This is a common disorder that’s passed down in families.

Family links: Analyzing hair follicles side by side sometimes can show if people are blood relatives.

Alopecia: If you’re losing hair or your hair doesn’t grow like it should, a close-up look can help your doctor figure out the best treatment.

Police evidence: Hair samples can help police identify suspects or victims after a crime.

Hair samples can be cut from the scalp or pulled up with the roots, depending on the reason for the test.

For some tests, you’ll need a lock of hair that’s 3 inches long and about the width of a pencil. If your hair is curly, the sample will be about the size of a cotton ball.

For other tests, you need hair that’s still attached to the roots. Your hair follicle, the part that’s inside your skin, has the most amount of your unique genetic code called DNA.

Hair follicle test kits are sold online to help confirm paternity. You need samples from both the baby and the presumed father. The person would need to agree to give it, and it’s unclear how accurate the tests may be.

Let the lab know all of the hair products that you use. That includes shampoo and conditioner, hair dyes, and hair straighteners. Some ingredients could mess up your results.

Usually, the lab will wash the sample to remove sweat, oil, skin cells, and other things. It may cut the hair into pieces or ground it into a powder before examining it under a microscope. The lab may also do a chemical analysis.

Hair analysis can be a useful tool, but there’s still a lot to learn about it. Because of this, you could be asked to take a different type of test so the results can be compared.

Health insurance doesn’t always cover the cost of hair analysis. Some insurers want more proof that this type of test is accurate.