The content provided on this blog is intended for educational purposes only and should not be construed as medical advice. We strongly advise readers to seek guidance from a qualified healthcare professional regarding any medical concerns.

To reflect its medicinal nature rather than recreational use, we prefer the term ‘medical cannabis’ over terms such as ‘marijuana’, “grass”. or ‘dope’ which may carry negative connotations.

The opinions expressed in the blog belong to the respective authors, who are not medical professionals, and may not necessarily align with those of Lyphe Clinic. Lyphe Clinic does not endorse any specific products or services mentioned, except those provided through Lyphe Clinic.

Readers should be aware that the legality of medical cannabis varies by location, and this disclaimer may be subject to periodic updates.

A physician holding a vial of blood for drug analysis.

Key Points

  • Drug testing for cannabis is a standard procedure often employed by both the legal system and employers. A positive result can result in you being denied employment, losing your current job, or facing prosecution.
  • Passing a cannabis drug screening involves preparation and understanding the examination process. You should familiarise yourself with the type of test being used, how long you can expect it to take, as well as the measures you ought to consider before and following the evaluation.
  • Some of the common ways to prepare for a drug test include drinking lots of water and abstaining from cannabis for a few days before the test. You can also try eating certain foods or taking detox supplements that contain ingredients like activated charcoal, B vitamins, or creatine.
  • It is important to understand and be aware of your rights as a patient and what steps you can take if you feel they have been violated.


In a world where drug testing has become increasingly common, passing a cannabis drug test has become a priority for many individuals. Whether it’s for employment, legal reasons, or personal goals, navigating these assessments successfully requires knowledge and preparation. To this end, this blog aims to provide a thorough and informative guide on passing a cannabis drug test, offering insights and strategies to increase your chances of a favourable outcome.

Importantly, please keep in mind that the guidance and suggestions provided in this blog are not a substitute for professional medical advice.

Lyphe: Revolutionising Medical Cannabis Care

The logo of Lyphe Clinic.

As the UK’s premier and most extensive medical cannabis clinic, Lyphe sets the gold standard in patient care and insight into the complexities of navigating drug tests. Our experts collaborate closely with patients to devise tailored treatment strategies. With a comprehensive grasp of your medical condition and necessary cannabis dosage, we guide you through your well-being journey while being mindful of drug test implications. 

Schedule an appointment with one of our esteemed doctors today, and empower yourself with a treatment plan that’s just right for you.

Understanding How Cannabis Is Detected in Drug Tests

Close-up of a researcher holding a flask filled with a yellow fluid.

Understanding how cannabis is detected in drug tests is crucial for anyone who may be subject to such examinations. Typically, drug tests look for the presence of THC (Tetrahydrocannabinol) or its metabolites, which are byproducts created when the body processes THC. These metabolites can be stored in fat cells and gradually eliminated through bodily fluids like urine, blood, and saliva. The method and sensitivity of the drug screening can greatly affect the identification window. 

However, it’s important to note that various factors such as metabolism, frequency of use, and even the potency of the cannabis can influence how long THC or its metabolites remain detectable in your system. Therefore, while there are general guidelines, individual results may vary.

Before we delve into the strategies to pass a cannabis drug test, let’s grasp the basics of these tests:

Test Type Detection Window Common Use Cases Limitations Additional Information
Urinalysis 3-30 days Pre-employment, random tests, workplace policies Can detect past use, not impairment Tests for THC-COOH, a metabolite of THC

Sensitivity can vary

Blood  Hours to 1-2 days Accidents, DUI, legal procedures Invasive, short detection timeframe Directly measures THC levels in the bloodstream

Often used to determine recent use

Saliva  Hours to 1-3 days Roadside tests, on-site immediate results Short detection window Less invasive than blood tests 

Often used for quick assessments

Hair Follicle Up to 90 days Pre-employment, legal cases, custody battles Can identify past use, not impairment Hair tests can provide a longer history of drug use but require a hair sample of sufficient length

General Strategies to Pass a Cannabis Drug Test

This section will examine top recommendations for successfully navigating a cannabis drug screening. While these guidelines are broadly applicable, the specifics may differ based on the nature of the test.

Time Your Consumption

The timing of your cannabis consumption plays a crucial role in determining your likelihood of passing a drug test. Research published in the Journal of Analytical Toxicology shows that the time between cannabis consumption and undergoing a drug test significantly influences the results. The more extended the interval between usage and the screening, the less likely it is to yield a positive outcome.

Moreover, as mentioned earlier, THC metabolites can linger in your system for varying durations, depending on various factors. For instance, the method of intake can also play a pivotal role. Here’s a general guideline:

Method of Consumption Detectable in Urine (Duration) Notes
Inhalation 1 to 30 days Depends on usage frequency
Edibles 1 to 30 days Depends on dosage and frequency
Topicals Unlikely to be detectable Typically don’t enter the bloodstream

If you know you’ll be facing a drug test, consider abstaining from cannabis for a sufficient amount of time before the test. Keep in mind that the longer the gap between your last consumption and the assessment, the better your chances of passing.

Stay Hydrated

Side view of man sitting and drinking water.

Staying well-hydrated is a viable strategy for reducing the concentration of THC metabolites in your urine, thus making it less likely for a drug test to detect their presence. By maintaining a higher fluid intake, you’re essentially diluting these substances within your system.

However, it’s crucial to strike a balance, as excessively diluted urine may draw attention. This could result in further scrutiny or the necessity for retesting. Overhydration could also pose health risks, such as electrolyte imbalances.

To navigate this carefully, you might opt to complement your water intake with B vitamins and creatine supplements. B vitamins can restore the natural yellow hue of your urine. Creatine supplements, on the other hand, can help to normalise the chemical composition. Both of these measures can make your urine sample appear more natural, thereby averting any potential flags for excessive dilution during testing.

Do note that these strategies are not foolproof, and the effectiveness may vary from person to person based on factors like metabolism, frequency of THC use, and the specific type of drug test administered. Always consult a medical professional for advice tailored to your individual circumstances.

Regular Exercise

Maintaining a healthy lifestyle can aid in the natural elimination of toxins, including THC metabolites, from your body. More specifically, regular exercise can help burn fat cells, which store the THC metabolites. However, the extent of this impact can vary based on several factors, including the regularity and vigour of physical activity, individual metabolism, and timing in relation to drug testing.

There is another caveat with exercise: the more you sweat, the more likely it is that THC metabolites will be released into your bloodstream. This can increase the risk of a positive test result. For instance, a study published in the journal Drug and Alcohol Dependence in 2013 found that acute exercise could temporarily increase THC metabolites in the bloodstream. Hence, if you are planning to take a drug test, it’s best to avoid any strenuous activities within the next 24 hours.

Use Home Drug Testing Kits

Home drug testing kits for THC are readily accessible for purchase, both online and at pharmacies, and can offer invaluable insights if you’re facing a drug examination in the near future. These kits operate on principles similar to those employed in professional facilities, making them a useful barometer for understanding how you may fare in an official test. Importantly, utilising one allows you to test yourself in the privacy and comfort of your own home, thus eliminating any anxieties or concerns you might have about initial screenings. 

However, it’s important to note that while these kits can be fairly reliable, they are not infallible. Variables such as the sensitivity of the test, the time since last THC use, and individual metabolic rates can all affect the outcome.

Detox Products

A bowl full of activated charcoal capsules.

A range of detoxification products, including detox beverages and tablets, are commercially available and purport to expedite the removal of THC metabolites from your system. While some individuals have reported success with these products, results can vary and may not be foolproof.

Some studies suggest that products containing activated charcoal (e.g., charcoal tablets) can help flush out THC metabolites from the body. For instance, one 2013 study published in Analytical and Bioanalytical Chemistry found that intake of 5mg of charcoal led to the binding of 1,000 ng/mL of free THC-COOH, the primary metabolite detected in cannabis drug tests.

It’s of paramount importance to conduct thorough research and opt for detox products from credible and well-reviewed sources. The efficacy of such products can vary widely, and some may contain ingredients that are ineffective or even potentially harmful. Therefore, it’s advisable to scrutinise product reviews, check for any scientific backing, and possibly consult healthcare professionals for recommendations tailored to your specific needs.

Be Honest With the Tester

If you’re subjected to a drug assessment, honesty is often the best policy. While the prospect may seem daunting, there are circumstances in which being forthright about your cannabis use could lead to a more sympathetic and understanding response from the testing authorities.

Firstly, if you possess a valid medical prescription for cannabis, disclosing this information upfront can simplify matters significantly. Similarly, if you reside in an area where recreational use of cannabis is legal, being honest about your usage can sometimes mitigate the repercussions of a positive test result. Some employers and testing authorities may adopt a more lenient stance in such cases, especially if your cannabis use doesn’t directly impact your job performance or breach any workplace policies.


Passing a cannabis drug test requires knowledge, preparation, and a mindful approach. By understanding the detection windows of different testing methods and implementing strategies tailored to each, individuals can increase their chances of successfully passing these examinations. It’s important to exercise caution, read product labels carefully, and consult with healthcare professionals or experts when necessary. 

As a distinguished UK medical cannabis clinic, we at Lyphe recommend that patients seek tailored advice from our healthcare professionals regarding the ideal dosage and frequency to reduce detection times. Committed to providing accurate information and specialised guidance on medical cannabis use, we invite you to book a consultation with one of our experts today.

Frequently Asked Questions (FAQs)

How long does cannabis stay in your system?

The length of time cannabis stays in your system varies depending on the type of test. In general, cannabis can be detected in urine for up to 30 days and in blood for up to 36 hours. It can be identified in saliva within several hours after use and may persist for up to 72 hours.

Do detox products work?

While some detox products claim to assist in eliminating cannabis metabolites from the body, it’s important to exercise caution and choose reputable products. Some lack scientific evidence and may do more harm than good.

Can I fail a drug test for secondhand smoke?

It’s unlikely but not impossible to fail a drug test from secondhand smoke. Exposure to large amounts of secondhand smoke in an unventilated room could potentially result in a positive test result.

Can medical cannabis users fail a drug test?

UK-specific guidelines and regulations do permit the use of medical cannabis for certain health conditions. However, it’s crucial to inform your employer or the testing facility about your prescription prior to undergoing the test.

What should I do if I fail a cannabis drug test?

If you fail a cannabis drug test, be honest and forthcoming with your employer or the testing facility. Corrective action can be taken depending on the situation, such as enrollment in an employee assistance program or job reassignment.


Böhnke E, Dietz L, Heinrich T, Aderjan R, Skopp G, et al. (2013) Disposition and Enterohepatic Circulation of Intravenously Administered 11-Nor-9-Carboxy-Δ9-Tetrahydrocannabinol in Serum and Urine in Healthy Human Subjects. J Forensic Toxicol Pharmacol 2:2. doi:10.4172/2325-9841.1000107

Niedbala, R.S., Kardos, K.W., Fritch, D.F., Kardos, T.F., & Waga, J. (2001). Detection of marijuana use by oral fluid and urine analysis following single-dose administration of smoked and oral marijuana. Journal of Analytical Toxicology, 25 (7/8), 289-303.

Skopp, G., & Mikus, G. (2013). An in vitro experiment on the interaction of charcoal or wheat bran with 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol and its glucuronide. Analytical and bioanalytical chemistry, 405(29), 9449–9453. https://doi.org/10.1007/s00216-013-7381-4

Wall, M. E., Sadler, B. M., Brine, D., Taylor, H., & Perez-Reyes, M. (1983). Metabolism, disposition, and kinetics of delta-9-tetrahydrocannabinol in men and women. Clinical Pharmacology & Therapeutics, 34(3), 352-363. https://doi.org/10.1038/clpt.1983.179

Wong, A., Montebello, M. E., Norberg, M. M., Rooney, K., Lintzeris, N., Bruno, R., Booth, J., Arnold, J. C., & McGregor, I. S. (2013). Exercise increases plasma THC concentrations in regular cannabis users. Drug and Alcohol Dependence, 133(2), 763-767. https://doi.org/10.1016/j.drugalcdep.2013.07.031

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