Milk Thistle Does Help in Passing a Urine Drug Test: How-to Guide and Scientific Evidence

Daniel Miller avatar
Daniel Miller, Ph.D, Drug Testing Specialist

Last updated on Jan 13, 2024

Milk thistle is said to have numerous protective effects on the liver and can, therefore, improve its functions.

The stoning community seems to have found another use of these pills, though; passing a urine drug test.

While the milk thistle method has more detractors than supporters, there is some sense in passing a urine drug test using it.

And I am here to bring you the basics of why and how it works, and the scientific clarification for that.

What is milk thistle?

In its natural form, milk thistle (also known as Silybum marianum, Mary thistle, or holy thistle) is a flowering herb native to Mediterranean countries.

Related to the ragweed and daisy family, the milk thistle features distinctive flowers and white veins.

The white veins are traditionally thought to have been caused when a drop of milk from the Virgin Mary fell onto the leaves.

Milk thistle has been reported to have many protective effects on several organs and systems in the body.

For instance, it is said to protect the heart by lowering LDL cholesterol levels.

Several scientific explorations also suggest that it improves insulin resistance and can help control type 2 diabetes.

However, this prickly plant is often promoted for its incredible effects on the liver and its perceived ability to improve its functions greatly.

Milk thistle is regularly recommended as a complementary therapy for people suffering from damaged liver caused by non-alcoholic fatty liver disease, alcoholic liver disease, liver cancer, and hepatitis.

It’s also typically used to treat several liver-related illnesses, including liver cirrhosis, chronic hepatitis, liver damage, and gallbladder disorder.

Also, extracts from this magical plant have been known to protect the liver from Amatoxin- a deadly toxin from the ‘death cap’ mushroom, which is known to cause severe liver damage.

Mind you, and it’s these numerous effects on the liver that make Mary thistle a remedy for passing a urine drug test.


How Can Milk Thistle Help to Pass a Urine Drug Test

Having gone through my proposed method of using Holy Thistle to pass a test, you could ask, ‘‘isn’t this simply the dilution method?’’

Sure, the milk thistle method involves consuming a lot of water.

And this helps in cutting the concentration of THC metabolites in your urine sample, which increases your chances of beating the test even further.

However, milk thistle also does play another important role here.

Milk thistle features a group of active ingredients that are collectively called silymarin. Milk thistle extracts usually have concentrations of between 65% and 80% of these active ingredients.

These ingredients have been found to inhibit the activity of drug-metabolizing enzymes found in the liver, namely the CYP (cytochrome P450) and the UGT (Uridine diphosphoglucuronosyl Transferase) enzymes.

Understanding the CYP and UGT enzymes

The CYP and UGT enzymes are the primary enzymes that are involved in the metabolism of cannabinoids. As I have illustrated in another article, THC is metabolized in 2 main stages.

Phase 1 of this process involves the active THC oxidation to its active metabolites 11-OH-THC and later to the inactive THC-COOH. The CYP enzymes do this process.

The UGT enzymes take over the second phase, which is also called the glucuronidation process. As this name suggests, this phase involves adding a glucuronide molecule to the inactive THC-COOH metabolite.

The end product of the glucuronidation process is THC-COO-glucuronide. Importantly, the glucuronide suffix indicates that these metabolites are ready for excretion either through urine or bile juice.

What happens when silymarin inhibits the activity of the enzymes?

By inhibiting the activity of the CYP enzymes, silymarin decreases the rate of THC metabolism.

Secondly, by inhibiting the activity of the UGT enzymes, the glucuronidation process is also slowed.

This means that there will be fewer THC-COO-glucuronide metabolites released for excretion through urine.

What does this mean? You guessed, right. It means that there will be fewer THC-COOH metabolites in your urine.

If the level of THC-COOH metabolites in urine is lower than the cut-off, you’ll have PASSED the test.

But wait. Is there any evidence that silymarin does inhibit the activity of the drug-metabolizing enzymes in humans?

I figured out that you would ask this question. So, I dug around and came across several studies that have been carried out around this topic.

Here is what I got.

Milk Thistle inhibits CYP and UGT Enzymes: Scientific Evidence.

Silymarin has long been hypothesized to hamper the activity of the CYP enzymes in rats and impair the glucuronidation process in the liver.

In this light, and considering that the liver is responsible for the metabolism of drugs, a study published in the Journal of American Society for Pharmacology and Experimental Therapeutics wanted to investigate whether silymarin has any interactions co-administered drugs.

It also aims to understand whether silymarin does inhibit the performance of the enzymes involved in drug metabolism in the liver.

The results were pretty much how they expected.

In this study, the researchers plated hepatocytes obtained from human donor liver on six plates that had been coated with rat-tail collagen.

Next, some of these specimens were untreated; others were acute silymarin treated (0.1 mM), while the rest were chronic silymarin treated (treated with 0.25 mM silymarin).

The researchers went ahead and examined the activity of CYP3A4 enzymes in the hepatocytes by measuring the formation of the 6-beta(OH) testosterone in both the untreated and the silymarin treated cultures.

The results were as illustrated in the figure below.


As these results show, the activity of the CYP3A4 enzymes was much higher in the untreated culture, slightly lower in the 0.1 mM silymarin treated culture, and almost insignificant in the 0.25 mM treated culture.

The researchers then went ahead and accessed UGT enzymes’ activity by measuring the formation of 4-MUG ( 4-methylumbelliferone glucuronide).

According to the figure below, the untreated cells formed 4-MUG at the rate of 0.35 nmol/min/mg of protein. Cells treated with Phenobarbital (PB) had a slightly higher formation.

On the other hand, cultures treated with 0.1 mM silymarin concentration had a notably lower MUG formation.

The formation was even much lower in the 0.25 mM silymarin treated culture.

Using Milk Thistle to Pass a Urine Drug Test

What you’ll need

Also, go for a brand that uses at least 80% silymarin in every pill. Most manufacturers will state the percentage in the ingredients list.


Step 1:

Abstain from the drugs at least until you are through the test – I did not have to mention this, but the last thing you want to do when trying to skirt a test is to add more drugs into your system.

Step 2: Start drinking a lot of water.

The moment you are alerted of a possible urine drug test, start drinking water and peeing whenever you feel the urge to.

If you have a day, ensure that you finish at least 1 gallon of water spread evenly.

The essence of this is to remove as much THC metabolites from the body as possible.

Step 3: Take 2-3 Milk Thistle pills per day with meals

Take a milk thistle pill with every meal totaling 3 pills each day. Most of these pills have milk thistle extract in the 150 -175mg range.

This supplement’s clinically proven dosage is 420mg spread evenly across the day and consumed 2-3 times.

This means that if you have less than a day to the test, you could ingest 2 pills at once without putting your life on the line.

Step 4: Test yourself regularly

Depending on the amount of time you have to the test, you must keep testing yourself to determine whether the method is working.

Testing strips that give you an approximate value of the level of THC concentration in your urine make it easy to decide whether or not to change the dose of water and pills.

Step 5: On the day of the test

Depending on the time you are scheduled to take the test, wake up early to start your daily cleansing regimen.

Start taking that day’s gallon of water plus a milk thistle tablet.

Note that you don’t really need to change your morning routine.

2 hours to the test, swallow another milk thistle pill plus the vitamin B2 pill and continue drinking the remaining part of the gallon of water.


As these results demonstrate, taking a few Holy thistle pills does inhibit the liver’s speed to metabolize THC into THC-COOH metabolites that the lab’s test for.

This means that it can actually help in passing a urine drug test.

However, as you may have noted, this is technically a 2-in-1 method of passing a urine drug test.

It involves minimizing the creation and release of THC-COOH metabolites in urine and diluting the little amounts of these metabolites that may be present in the urine.

In my opinion, this not only increases your chances of beating the test by 2 folds, but it also makes it easy for everyone to pass a test even on short notice.

Remember that over-diluting your urine can land you in trouble, though.

This happens when you consume a lot of water without minding certain important urine values such as creatinine and the specific gravity levels.

Instead of using this unreliable method, I recommend using detox products proven to work:

Frequently Asked Questions

The milk thistle method involves drinking copious amounts of water. Isn’t it simply the dilution method?

The water in this method boosts your chances of beating the test by diluting any available THC-COOH metabolites in the urine below the cut-off levels.

However, silymarin (the active ingredients in Mary thistle) works by minimizing the speed at which the CYP and the UGT enzymes in the liver metabolize THC to THC-COOH THC-COOH to THC-COO-glucuronide, respectively.

Does milk thistle help in detoxing cannabis?

Although milk thistle minimizes the number of THC metabolites available for detection in the urine, remember that it does not boost detoxification. In any case, it does the opposite.

The fact that it negatively affects how the CYP and UGT enzymes remove THC from the body means that it will prolong the detoxification process.

Will exercising before the test make it hard to pass using the Milk thistle method?

There is an ongoing rumor that exercising before the test could make it hard for you to pass a urine test.

Technically, there is some sense in this claim. THC is highly lipophilic, i.e., highly soluble in fat.

As you exercise, the fat-stored THC is released into the plasma as the fat cells get burned for energy.

However, Worth mentioning is that what is released are the THC molecules, not the THC-COOH, which labs test for.

Studies show that the increased THC levels in the blood plasma only lasts for 2 hours.

So, NO, exercising won’t ahead of a test affect the urine drug test results immediately.

Read more about this myth in my other article on working out to pass a drug test here.

100% Success Rate for Passing Drug Tests!

Clear Choice Sub-Solution is the perfect solution for passing a drug test. It contains a clean synthetic urine that is biocide free and completely undetectable.

It also comes with their patented heat activator formula that raises the urine’s temperature to normal body temperature within seconds, so you don’t need to worry about having to heat it up yourself.

Furthermore, the standard size container makes it easy to conceal, and it is unisex, so it can be used by both male and female users.

The information on this website about detox products and synthetic urines is for educational purposes only. We do not endorse or condone their illegal use. Always consider the laws in your area and the potential legal consequences. Consult with a healthcare professional before using any products. Your responsibility and well-being are paramount.