Detection time for weed in hair

 Wondering, how long does weed stay in your hair? If yes, this article was prepared for you. Marijuana, ganja, pot, and weed are some of the commonly used terms when referring to Cannabis. This substance is one of the most abused drugs worldwide as a result it is considered illegal in most countries including The United States.

Weed is obtained from the plant Cannabis sativa and it is native to Central and Southern Asia.

Weed is extracted from the leaves, stems as well as dried flower buds of this plant. The main components of cannabis include tetrahydrocannabinol (THC) and cannabidiol (CBD).

It is mostly taken by smoking blunts or pipes and also eaten as food extract. Marijuana has various applications ranging from biomedical purposes to recreational ones.  In the medical field, weed is used to boost appetites, to treat epilepsy, asthma as well as many other ailments. High doses and recreational use of weed may result in a person losing focus, being aggressive, and generally losing control of their senses and continual use may lead to addiction.

Examples of countries where weed is legal

  • Canada
  • South Africa
  • Netherlands
  • Mexico
  • Australia

Properties Of The Cannabinoids found in Cannabis

Component NamePropertyEffect
THCMain psychoactive component*Feeling euphoria, paranoia, increased appetite, loss of focus
CBDNon-psychoactiveAnticonvulsant action

How is THC metabolized?

When an individual smokes weed, it is transferred from the respiratory system to the brain and different organs. THC binds to the receptors on the brain and triggers them to release various hormones such as dopamine which then creates a feeling of euphoria.  In the liver, the enzyme cytochrome P450 (CYP) catalyzes the hydroxylation and oxidation reactions to break down THC into II- hydroxy-THC and other metabolites which are then excreted via the urinary system.

How is weed tested and analyzed?

After exposure to weed, it can be detected in a person’s blood, saliva, hair, nails as well as urine using various analytical methods and immunoassays. The Hair follicle drug test is one of the commonly used tests because it is convenient, it can be performed anywhere be it home, health facility, or at work. It takes less time to conduct as compared to urine and blood tests. The hair follicle drug test checks for illegal drug use as well as overdosing and misusing prescriptions. The drug as well as its metabolites are analyzed using these hair tests. The specimen can be collected from any body part provided the thickness of the hair meets the required standard.  The tester only needs to collect 100 mg of hair as the specimen for testing. The specimen is then cleaned up to eliminate external contaminants before being digested in a solution that tears them into its components. Afterward, various immunoassays such as the “Enzyme-Linked Immunosorbent Assay” (ELISA), are used to carry out initial screening tests. The positive results are then confirmed using analytical techniques such as gas chromatography and Mass spectrometry. 0.1 picograms per milligram of hair is used to confirm the presence of THC. Levels above this prove that a person has been using weed for the past 90 days.

How does weed get in my hair?

As previously mentioned, smoking or taking any form of marijuana means that the drug ends up being absorbed into the bloodstream. From there, its active components connect to specific receptors on the brain where they end up triggering the release of various hormones. Moreover, some THC metabolites may enter the bloodstream and be absorbed into various cells including the hair cells. THC is then carried upwards from the hair roots where it can then be detected with hair THC tests for 90 days.

How long does weed stay in your hair?

THC takes 3 months in the hair which is generally based on the time needed for root hairs to sprout past the scalp and be long enough to be taken as a specimen for a  hair follicle drug test. CBD on the other hand stays for an average of two to five days in a person’s body.

Factors that influence how long marijuana remains in an individual’s system

These factors vary from person to person because some of them such as age and body mass index are unique to each individual and influence how the body breaks down THC and its metabolites. Some of the factors stated below depends on the dose and usage of weed by each individual.

  • Levels of THC in the weed

The higher the dose the higher the amount of THC in the weed. This means marijuana will stay a bit longer in the person’s body due to the high levels of the main psychoactive component. These higher doses also double the time taken for the weed to be removed from the body.

  • Number of times the drug is used

The frequency of usage also determines how long THC will stay in a person’s body. Regular use of weed increases the time taken for the drug to be removed from a person’s body.

  • Level of Hydration

Lower water levels in the body increase the concentrations of THC and its metabolites hence making it lasts longer in the system.

  • Metabolism rates

People have various body fat concentrations. Weed is normally stored in the body’s fat tissues. As FMAHealth specifies, individuals with less body fat may break down THC faster than their counterparts with higher body fat.  One way to increase metabolic rates and help the body break down THC faster is through regular intense exercises.

Can you cheat a hair follicle drug test?

Possibly yes. Some people believe that using detox kits or pills will help them break down and eliminate weed faster from their bodies. However, this is wrong for hair and cannot help anyone pass a hair follicle drug test. One possible way to cheat a hair test is through bleaching hair to pass a hair follicle drug test.  Bleaching hair eliminates more than 80% of drug components and their metabolites from an individual’s system. This is because hair is broken down and destroyed during bleaching which then leads to loss of metabolites from the hair. Hair relaxers, shampoos, and dyes also lower the levels of metabolites on the hair, therefore, affecting the quality of the hair drug tests. FMA Health recommends abstaining from marijuana for 3 months or more to guarantee the method for anyone wondering about how to pass a hair follicle drug test.


  • Carolyn Gaughan

    Carolyn Gaughan is an ex-executive vice president of the Kansas Academy of Family Physicians and represents the state associations of the American Academy of Family Physicians and the American College of Osteopathic Family Physicians.