Mercaptopurine and Weed

{Fulldrug} and Weed

Authored by Pin Ng PhD

Edited by Hugh Soames

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Mercaptopurine and Weed


Most people who consume marijuana do so for its mood-altering and relaxing abilities. Weed gives people a high and allows them to relax. However, heavy consumption of weed can cause unwanted results. It can increase the anxiety and depression a person experiences, and it can interact with certain other drugs including Mercaptopurine. It is important to remember that interactions do occur with all types of drugs, to a great or lesser extent and this article details the interactions of mixing Mercaptopurine and Weed.


Mixing Mercaptopurine and Weed


Mercaptopurine (6-MP), sold under the brand name Purinethol among others, is a medication used for cancer and autoimmune diseases. Specifically it is used to treat acute lymphocytic leukemia (ALL), acute promyelocytic leukemia (APL), Crohn’s disease, and ulcerative colitis. For acute lymphocytic leukemia it is generally used with methotrexate. It is taken by mouth.

Common side effects include bone marrow suppression, liver toxicity, vomiting, and loss of appetite. Other serious side effects include an increased risk of future cancer and pancreatitis. Those with a genetic deficiency in thiopurine S-methyltransferase are at higher risk of side effects. Use in pregnancy may harm the baby. Mercaptopurine
is in the thiopurine and antimetabolite family of medications.

Mercaptopurine was approved for medical use in the United States in 1953. It is on the World Health Organization’s List of Essential Medicines.

It is used to treat acute lymphocytic leukemia, Crohn’s disease, and ulcerative colitis.

Some of the adverse reactions of taking mercaptopurine may include diarrhea, nausea, vomiting, loss of appetite, fatigue, stomach/abdominal pain, weakness, skin rash, darkening of the skin, and hair loss. Serious adverse reactions include mouth sores, fever, sore throat, easy bruising or bleeding, pinpoint red spots on the skin, yellowing of eyes or skin, dark urine, and painful or difficult urination. Other more serious side effects include black or tarry stools (melena), bloody stools, and bloody urine. Treatment is discontinued in up to 30% of patients due these effects but therapeutic drug monitoring of the biologically active metabolites, i.e. thiopurine nucleotides can help to optimize the efficacy and safety. Clinically, most hospitals resort to on-exchange LC-MS (liquid chromatography – mass spectrometry) but the newly developed approach of porous graphitic carbon based chromatography hyphenated with mass spectrometry appears superior with respect to patient care in this respect.

Symptoms of allergic reaction to mercaptopurine include rash, itching, swelling, dizziness, trouble breathing, and inflammation of the pancreas.

In some cases, mercaptopurine may suppress the production of blood cells, both white blood cells and red blood cells. It may be toxic to bone marrow. Quarterly blood counts are necessary for people on mercaptopurine. People should stop taking the medication at least temporarily while considering alternate treatment if there is an unexplained, abnormally large drop in white blood cell count, or any other blood count.

Toxicity of mercaptopurine can be linked to genetic polymorphisms in thiopurine S-methyltransferase (TPMT), nudix hydrolase 15 (NUDT15), and inosine triphosphate pyrophosphatase (ITPA). People with specific allele variants will require dose adjustments, especially for those with homozygous variant genotypes. Large differences of TPMT and NUDT15 among ethnicities in terms of variant allele frequency should be taken into consideration in clinical practice. Caucasian people with a variant allele of the ITPA gene, experience higher rates of febrile neuropenia than people of other ethnic groups, due to differences in allelic frequencies among ethnicities.

Mercaptopurine can lower the body’s ability to fight off infection. Those taking it should get permission from a doctor to receive immunizations and vaccinations. It is also recommended that, while on the drug, one should avoid those having recently received oral polio vaccine.

This drug was formerly not recommended during pregnancy and early evidence indicated pregnant women on the drug (or the related azathioprine) showed a seven-fold incidence of fetal abnormalities as well as a 20-fold increase in miscarriage. There were also anecdotal reports linking mercaptopurine with spontaneous abortion, leading to the US FDA rating both AZA and mercaptopurine as category D drugs. However, Davis et al. 1999 found mercaptopurine, compared to methotrexate, was ineffective as a single-agent abortifacient; every woman in the mercaptopurine arm of the study had fetal cardiac activity at follow-up (two weeks later) and was given a suction abortion. A more recent, larger study, however, performed by the Cancers et Surrisque Associe aux Maladies inflamatoires intestinales En France (CESAME) indicated an overall rate of congenital malformations not significantly greater than the general population in France. The European Crohn’s and Colitis Organisation (ECCO) concluded in a consensus paper in 2010 that while AZA and mercaptopurine have an FDA rating of D, new research in both animals and humans indicates that “thiopurines are safe and well tolerated during pregnancy.”

Mercaptopurine causes changes to chromosomes in animals and humans, though a study in 1990 found, “while the carcinogenic potential of 6-MP cannot be precluded, it can be only very weak or marginal.” Another study in 1999 noted an increased risk of developing leukemia when taking large doses of 6-MP with other cytotoxic drugs.

Allopurinol inhibits xanthine oxidase, the enzyme that breaks down mercaptopurine. Those taking allopurinol (often used to prevent gout) are at risk for mercaptopurine toxicity. The dose should be reduced or allopurinol should be discontinued.
Several published studies have demonstrated that the use of allopurinol in combination with low dose 6-MP helps reduce 6-MP levels, which are toxic to liver tissue, whilst increasing the therapeutic levels of 6-MP for some inflammatory conditions.

Official information from the package insert for purinethol:

6-MP ribonucleotide inhibits purine nucleotide synthesis and metabolism by inhibiting an enzyme called phosphoribosyl pyrophosphate amidotransferase (PRPP amidotransferase). Since this enzyme is the rate limiting factor for purine synthesis, this alters the synthesis and function of RNA and DNA.[citation needed] Mercaptopurine interferes with nucleotide interconversion and glycoprotein synthesis.

The enzyme thiopurine S-methyltransferase (TPMT) is responsible, in part, for the inactivation of 6-mercaptopurine. TPMT catalyzes the methylation of 6-mercaptopurine into the inactive metabolite 6-methylmercaptopurine – this methylation prevents mercaptopurine from further conversion into active, cytotoxic thioguanine nucleotide (TGN) metabolites. Certain genetic variations within the TPMT gene can lead to decreased or absent TPMT enzyme activity, and individuals who are homozygous or heterozygous for these types of genetic variations may have increased levels of TGN metabolites and an increased risk of severe bone marrow suppression (myelosuppression) when receiving mercaptopurine. In many ethnicities, TPMT polymorphisms that result in decreased or absent TPMT activity occur with a frequency of approximately 5%, meaning that about 0.25% of people are homozygous for these variants. However, an assay of TPMT activity in red blood cells or a TPMT genetic test can identify people with reduced TPMT activity, allowing for the adjustment of mercaptopurine dose or avoidance of the drug entirely. The FDA-approved drug label for mercaptopurine recommends testing for TPMT activity to identify people at risk for myelotoxicity. Testing for TPMT activity is an example of pharmacogenetics being translated into routine clinical care.

6-MP was discovered by Nobel Prize winning scientists Gertrude B. Elion and George H. Hitchings at Burroughs Wellcome in Tuckahoe, New York, and was clinically developed in collaboration with investigators at Memorial Hospital (now Memorial Sloan Kettering Cancer Center in New York City). The collaboration was initiated by Cornelius P. Rhoads who had run chemical weapons programs for the US army and had been involved in the work that led to the discovery that nitrogen mustards could potentially be used as cancer drugs, and had become the director of Memorial in 1948.


Research has found that anxiety is one of the leading symptoms created by marijuana in users, and that there is a correlation between Mercaptopurine and Weed and an increase in anxiety.


Anyone mixing Mercaptopurine and weed is likely to experience side effects. This happens with all medications whether weed or Mercaptopurine is mixed with them. Side effects can be harmful when mixing Mercaptopurine and weed. Doctors are likely to refuse a patient a Mercaptopurine prescription if the individual is a weed smoker or user. Of course, this could be due to the lack of studies and research completed on the mixing of Mercaptopurine and Weed.


Heavy, long-term weed use is harmful for people. It alters the brain’s functions and structure, and all pharmaceuticals and drugs including Mercaptopurine are designed to have an impact on the brain. There is a misplaced belief that pharmaceuticals and medication work by treating only the parts of the body affected yet this is obviously not the case in terms of Mercaptopurine. For example, simple painkiller medication does not heal the injury, it simply interrupts the brains functions to receive the pain cause by the injury. To say then that two drugs, Mercaptopurine and Weed, dol not interact is wrong. There will always be an interaction between Mercaptopurine and Weed in the brain11.J. D. Brown and A. G. Winterstein, Potential Adverse Drug Events and Drug–Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from


One of the milder side effects of mixing Mercaptopurine and Weed is Scromiting. This condition, reportedly caused by mixing Mercaptopurine and Weed, describes a marijuana-induced condition where the user experiences episodes of violent vomiting, which are often so severe and painful that they cause the person to scream. The medical term for Scromiting by mixing Mercaptopurine and Weed is cannabinoid hyperemesis syndrome, or CHS.  For these reasons, some people choose to quit smoking weed.


It was first included in scientific reports in 2004. Since then, researchers have determined that Scromiting is the result of ongoing, long-term use of marijuana—particularly when the drug contains high levels of THC, marijuana’s main psychoactive ingredient. Some experts believe that the receptors in the gut become overstimulated by THC, thus causing the repeated cycles of vomiting.


In the long run, a person can become even more depressed. There is a belief that marijuana is all-natural and not harmful to a person’s health. This is not true and Mercaptopurine and weed can cause health issues the more a person consumes it.


How does Weed effect the potency of Mercaptopurine?


The way in which the body absorbs and process Mercaptopurine may be affected by weed. Therefore, the potency of the Mercaptopurine may be less effective. Marijuana inhibits the metabolization of Mercaptopurine. Not having the right potency of Mercaptopurine means a person may either have a delay in the relief of their underlying symptoms.


A person seeking Mercaptopurine medication that uses weed should speak to their doctor. It is important the doctor knows about a patient’s weed use, so they can prescribe the right Mercaptopurine medication and strength. Or depending on level of interactions they may opt to prescribe a totally different medication. It is important for the doctor to know about their patient’s marijuana use. Weed is being legalized around the US, so doctors should be open to speaking about a patient’s use of it.


Sideffects of Mercaptopurine and Weed


Many individuals may not realize that there are side effects and consequences to mixing Mercaptopurine and Weed such as:


  • Dizziness
  • Sluggishness
  • Drowsiness
  • Shortness of breath
  • Itching
  • Hives
  • Palpitations
  • Respiratory Depression
  • Cardiac Arrest
  • Coma
  • Seizures
  • Death


Interestingly, it is impossible to tell what effect mixing this substance with Weed will have on an individual due to their own unique genetic make up and tolerance. It is never advisable to mix Mercaptopurine and Weed due to the chances of mild, moderate and severe side effects. If you are having an adverse reaction from mixing Mercaptopurine and Weed it’s imperative that you head to your local emergency room. Even mixing a small amount of Mercaptopurine and Weed is not recommended.


Taking Mercaptopurine and Weed together


People who take Mercaptopurine and Weed together will experience the effects of both substances. Technically, the specific effects and reactions that occur due to frequent use of Mercaptopurine and weed depend on whether you consume more weed in relation to Mercaptopurine or more Mercaptopurine in relation to weed.


The use of significantly more weed and Mercaptopurine will lead to sedation and lethargy, as well as the synergistic effects resulting from a mixture of the two medications.


People who take both weed and Mercaptopurine may experience effects such as:


  • reduced motor reflexes from Mercaptopurine and Weed
  • dizziness from Weed and Mercaptopurine
  • nausea and vomiting due to Mercaptopurine and Weed


Some people may also experience more euphoria, depression, irritability or all three. A combination of weed and Mercaptopurine leads to significantly more lethargy which can easily tip over into coma, respiratory depression seizures and death.

Mixing weed and Mercaptopurine


The primary effect of weed is influenced by an increase in the concentration of the inhibitory neurotransmitter GABA, which is found in the spinal cord and brain stem, and by a reduction in its effect on neuronal transmitters. When weed is combined with Mercaptopurine this primary effect is exaggerated, increasing the strain on the body with unpredictable results.


Weed and Mercaptopurine affects dopamine levels in the brain, causing the body both mental and physical distress. Larger amounts of Mercaptopurine and weed have a greater adverse effect yet leading medical recommendation is that smaller does of Mercaptopurine can be just as harmful and there is no way of knowing exactly how Mercaptopurine and weed is going to affect an individual before they take it.


Taking Mercaptopurine and weed together


People who take Mercaptopurine and weed together will experience the effects of both substances. The use of significantly more Mercaptopurine with weed will lead to sedation and lethargy, as well as the synergistic effects resulting from a mixture of the two medications.


People who take both weed and Mercaptopurine may experience effects such as:


  • reduced motor reflexes from Mercaptopurine and weed
  • dizziness from weed and Mercaptopurine
  • nausea and vomiting of the Mercaptopurine


Some people may also experience more euphoria, depression, irritability or all three. A combination of weed and Mercaptopurine leads to significantly more lethargy which can easily tip over into coma, respiratory depression seizures and death.

Weed Vs Mercaptopurine


Taking Mercaptopurine in sufficient quantities increases the risk of a heart failure. Additionally, people under the influence of Mercaptopurine and weed may have difficulty forming new memories. With weed vs Mercaptopurine in an individual’s system they become confused and do not understand their environment. Due to the synergistic properties of Mercaptopurine when mixed with weed it can lead to confusion, anxiety, depression and other mental disorders. Chronic use of Mercaptopurine and weed can lead to permanent changes in the brain22.G. Lafaye, L. Karila, L. Blecha and A. Benyamina, Cannabis, cannabinoids, and health – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from


Mercaptopurine Vs Weed


Studies investigating the effects of drugs such as Mercaptopurine and weed have shown that the potential for parasomnia (performing tasks in sleep) is dramatically increased when Mercaptopurine and weed are combined. Severe and dangerous side effects can occur when medications are mixed in the system, and sleep disorders are a common side effect of taking weed and Mercaptopurine together.


When a small to medium amount of weed is combined with Mercaptopurine, sleep disorders such as sleep apnea can occur. According to the latest data from the US Centers for Disease Control and Prevention (CDC) most ER visits and hospitalizations caused by too much weed were associated with other substances such as Mercaptopurine.


How long after taking Mercaptopurine can I smoke weed or take edibles?


To avoid any residual toxicity it is advisable to wait until the Mercaptopurine has totally cleared your system before taking weed, even in small quantities.


Overdose on Mercaptopurine and weed


In the case of Overdose on Mercaptopurine or if you are worried after mixing Mercaptopurine and weed, call a first responder or proceed to the nearest Emergency Room immediately.


If you are worried about someone who has taken too much Mercaptopurine or mixed weed with Mercaptopurine then call a first responder or take them to get immediate medical help. The best place for you or someone you care about in the case of a medical emergency is under medical supervision. Be sure to tell the medical team that there is a mix of Mercaptopurine and weed in their system.


Excessive Weed intake and result in scromiting, chs, and anxiety disorder.  It is advisable to quit vaping weed if you are feeling these symptoms.

Mixing Mercaptopurine and weed and antidepressants


Weed users feeling depressed and anxious may be prescribed antidepressant medication. There are some antidepressant users who also use Mercaptopurine and weed. These individuals may not realize that there are side effects and consequences to consuming both Mercaptopurine, marijuana and a range of antidepressants.


Studies on weed, Mercaptopurine and antidepressants is almost nil. The reason for so little information on the side effects of the two is mostly down to marijuana being illegal in most places – although a number of states in the United States have legalized the drug.


Self-medicating with Weed and Mercaptopurine


A lot of people suffer from depression caused by weed and Mercaptopurine. How many? According to Anxiety and Depression Association of America (ADAA), in any given year, it is estimated that nearly 16 million adults experience depression. Unfortunately, that number is likely to be wrong due to under reporting. Many people do not report suffering from depression because they do not want to be looked at as suffering from a mental illness. The stigmas around mental health continue and people do not want to be labeled as depressed.


Potential side effects from mixing Mercaptopurine and weed


Quitting weed to take Mercaptopurine


Medical professionals say an individual prescribed or taking Mercaptopurine should not stop using weed cold turkey.  Withdrawal symptoms can be significant. Heavy pot users should especially avoid going cold turkey. The side effects of withdrawal from weed include anxiety, irritability, loss of sleep, change of appetite, and depression by quitting weed cold turkey and starting to take Mercaptopurine.


A person beginning to use Mercaptopurine should cut back on weed slowly. While reducing the amount of weed use, combine it with mindfulness techniques and/or yoga. Experts stress that non-medication can greatly improve a person’s mood.


Weed and Mercaptopurine can affect a person in various ways. Different types of marijuana produce different side effects. Side effects of weed and Mercaptopurine may include:


  • loss of motor skills
  • poor or lack of coordination
  • lowered blood pressure
  • short-term memory loss
  • increased heart rate
  • increased blood pressure
  • anxiety
  • paranoia
  • increased energy
  • increased motivation


Mixing Mercaptopurine and weed can also produce hallucinations in users. This makes marijuana a hallucinogenic for some users. Weed creates different side effects in different people, making it a very potent drug. Now, mixing Mercaptopurine or other mental health drugs with weed can cause even more unwanted side effects.


Mixing drugs and weed conclusion


Long-term weed use can make depression and anxiety worse. In addition, using marijuana can prevent Mercaptopurine from working to their full potential33.J. D. Brown and A. G. Winterstein, Potential Adverse Drug Events and Drug–Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from Weed consumption should be reduced gradually to get the most out of prescription medication. Marijuana is a drug and it is harmful to individual’s long-term health. Weed has many side effects and the consequences are different to each person who uses it, especially when mixed with Mercaptopurine.


If you take Mercaptopurine, and also drink Alcohol or MDMA, you can research the effects of Mercaptopurine and Alcohol , Mercaptopurine and Cocaine as well as Mercaptopurine and MDMA here.


To find the effects of other drugs and weed refer to our Weed and Other Drugs Index A to L or our Weed and Other Drugs Index M-Z.

Or you could find what you are looking for in our Alcohol and Interactions with Other Drugs index A to L or Alcohol and Interactions with Other Drugs index M to Z , Cocaine and Interactions with Other Drugs index A to L or Cocaine and Interactions with Other Drugs index M to Z or our MDMA and Interactions with Other Drugs Index A to L or MDMA and Interactions with Other Drugs Index M to Z.


Mercaptopurine and Weed

Mercaptopurine and Weed

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  • 1
    1.J. D. Brown and A. G. Winterstein, Potential Adverse Drug Events and Drug–Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from
  • 2
    2.G. Lafaye, L. Karila, L. Blecha and A. Benyamina, Cannabis, cannabinoids, and health – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from
  • 3
    3.J. D. Brown and A. G. Winterstein, Potential Adverse Drug Events and Drug–Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use – PMC, PubMed Central (PMC).; Retrieved September 27, 2022, from