Marijuana is a popular recreational drug that has gained widespread acceptance recently. However, despite its growing popularity, many people are still unaware of some of the basics of marijuana use, such as how long it stays in the body.
While the effects of marijuana on the body can vary depending on the frequency and dosage of use, one of the most common questions users ask is how long it stays in the hair. This is a crucial question, especially for those subject to drug testing, such as job applicants or athletes. In this article, I’ll explore the science behind how marijuana gets into the hair, how long it stays there, and what factors can affect its detection.
When a person consumes marijuana, some cannabinoids (the active compounds in marijuana) can be deposited in their hair. The duration of detectability can depend on several factors, such as the frequency and amount of marijuana use, the person’s hair growth rate and length, and the sensitivity of the testing method.
Research suggests that THC, the main psychoactive component of marijuana, can be detectable in hair for up to 90 days or more after last use. Other cannabinoids, such as CBD, may also be detectable in hair, but for a shorter duration. Hair testing for marijuana is commonly used in workplace drug testing, law enforcement, and other settings. However, the accuracy and reliability of these tests can vary, and false positives and negatives can occur. Hair samples can also be contaminated by external sources of cannabinoids, such as secondhand smoke or contact with marijuana-infused products.
It’s important to note that the presence of cannabinoids in hair does not necessarily correspond to the level of impairment or intoxication. Hair testing can only indicate past use, and cannot determine the exact timing or frequency of use. If a person is concerned about the potential for a positive hair test, they should consult a healthcare provider or legal professional. It’s also worth noting that some hair detoxification products and methods are available on the market, but their effectiveness and safety are not well established.
Whether you’re a casual user or someone who needs to pass a drug test, this article will provide the information you need to know.
How marijuana enters the hair
To understand how marijuana gets into the hair, it’s essential to understand how it works in the body. When you smoke, ingest, or inhale marijuana, it enters the bloodstream and spreads throughout your body. As it moves through your system, it passes through your hair follicles, which are small openings in your skin that produce hair. Once marijuana enters your hair follicles, it becomes trapped in the hair shaft, which remains until the hair falls out or is cut.
The reason marijuana is detectable in hair is because it contains a compound called THC (tetrahydrocannabinol), the active ingredient in marijuana that produces the “high” sensation. THC is fat-soluble, which binds to the fats in your body and can be stored in your hair for a long time.

How long can marijuana stay in the hair?
The amount of time that marijuana stays in your hair depends on several factors, such as the frequency and dosage of use, the type of test being used, and the test’s sensitivity. On average, marijuana can be detected in hair samples for up to 90 days after use.
However, it’s worth noting that hair tests are not always accurate and can produce false positives. For example, if you were near someone who was smoking marijuana, you could absorb some of the THC through your hair and produce a positive test result, even if you didn’t use the drug yourself.
Factors that affect marijuana detection in hair
Several factors can affect how long marijuana stays in your hair and how easily it can be detected. These include:
Hair color and type
Dark hair tends to hold onto drugs longer than light hair, as the pigment in darker hair can bind more easily to drug molecules. Additionally, curly or coarse hair can trap drugs more effectively than straight hair, meaning that drug residues can be more challenging to remove.
Frequency and dosage of use
The more often you use marijuana and the higher the dose, the more likely it is to be detectable in your hair. Infrequent or low-dose users are less likely to test positive.
Length of hair
The longer your hair, the more likely it is that drugs will be detectable. Hair grows at an average rate of half an inch per month, meaning that hair samples taken from different parts of your head could show different drug histories.
Bleaching or dyeing hair
Chemicals used in hair treatments, such as bleaching and dyeing, can break down drug molecules, making them less detectable in hair samples.
Hair drug testing methods
Hair drug tests are becoming increasingly popular for detecting marijuana use, as they are more accurate and less invasive than other types of drug tests. There are two primary methods of hair drug testing:
ELISA (enzyme-linked immunosorbent assay)
This is a preliminary screening test that looks for the presence of THC in hair samples. ELISA tests are relatively quick and inexpensive but can produce false positives.
GC/MS (gas chromatography/mass spectrometry)
This is a more definitive test that confirms the presence of THC in hair samples. GC/MS tests are more accurate than ELISA tests and can detect lower levels of THC, but they are more expensive and time-consuming.
False positives in hair drug testing
As mentioned earlier, hair drug testing is inaccurate and can produce false positives. This can happen for several reasons, such as:
Secondhand exposure
If you’re around people who are smoking marijuana, you could absorb some of the THC through your hair and produce a positive test result.
Contamination
Hair samples can become contaminated with drugs from external sources, such as contact with drug users or exposure to drugs in the environment.
Laboratory error
Human error can occur during the testing process, leading to inaccurate results.

How to pass a hair drug test for marijuana
If you’re concerned about testing positive for marijuana use in a hair drug test, there are several things you can do to try to pass the test:
Stop using marijuana
The most effective way to pass a hair drug test is to stop using marijuana altogether. This will give your body time to eliminate any THC from your system and reduce the likelihood of a positive test result.
Use detox products
Many detox products claim to remove drugs from hair, but their effectiveness is not always guaranteed. Some of these products can be harsh on hair and scalp, so it’s important to research them thoroughly before use.
Shave your head
While extreme, shaving your head can remove all traces of drugs from your hair, making it impossible to test for marijuana use.
Home remedies for removing marijuana from hair
If you’re looking for a more natural way to remove marijuana from your hair, you can try several home remedies. However, it’s essential to note that these remedies have not been scientifically proven to be effective, and their success may depend on the individual.
Apple cider vinegar
Rinsing your hair with apple cider vinegar can help to remove drug residues from the hair shaft.
Baking soda
Mixing baking soda with water to create a paste and applying it to your hair can help to strip away drug residues.
Lemon juice
Applying lemon juice to your hair and sitting in the sun for a few hours can help to break down THC molecules in your hair.
Conclusion and final thoughts
In conclusion, marijuana can stay in the hair for up to 90 days after use, depending on several factors such as hair color and type, frequency and dosage of use, and length of hair. Hair drug testing is becoming more popular to detect marijuana use, but false positives can occur due to secondhand exposure, contamination, or laboratory error.
If you’re concerned about testing positive for marijuana use, you can try stopping use, using detox products, or shaving your head. However, it’s important to remember that the most effective way to pass a hair drug test is to stop using marijuana altogether.