Print Friendly, PDF & Email

THC has some potent effects against cancer, heart disease, pain, nausea and insomnia. It can also help with seizures, insulin sensitivity and improve brain function in certain ways.


Tetrahydrocannabinol (THC), also known as delta9-tetrahydrocannabinol, is the primary component of cannabis responsible for its psychoactive properties. It is considered a secondary metabolite of the plant marijuana that serves as a defense mechanism to prevent consumption of the plant (R).

THC in the Cannabis plant needs to be heated in order to be efficiently utilized by the body (R).

Medical use of cannabis dates back as far as 16th century B.C. by the Egyptians, and subsequently by the Greeks and Romans. A cannabis extract containing THC metabolites was found inside a tomb in Israel on remains of a young woman who appeared to have died giving birth (R). The archeologists who discovered the tomb speculated that the cannabis was used to facilitate the birth process.

Current Uses of THC in Medicine

Although CBD may be a more popular constituent of cannabis for therapeutic purposes, synthetic forms of THC such as Dronabinol have been approved for the treatment of nausea, vomiting, and loss of appetite in chemotherapy and AIDS patients (R).

Nabiximols, a cannabis extract, is a spray that can ease the symptoms of other spastic symptoms of treatment-resistant multiple sclerosis (R).

Route of Administration and Pharmacokinetics of THC 

There are many different routes of administration, with varying absorption and elimination rates, depending on the purpose of use (R).

  • Smoking or absorption of THC via the lungs result in rapid and efficient absorption with 2 – 56% bioavailability of THC and its metabolites. Peak levels in the blood is detected after 12 minutes.
  • Oral or ingestion of THC result in a lower, more gradual and blunted peak in serum concentration of THC. Serum levels peak at around 1.5 – 2 hours. Chocolate cookies with cannabis has ~6% bioavailability 1 – 5 hour post-ingestion. The absorbed cannabis is also subject to first-pass liver metabolism.
  • Sublingual, rectal, and skin uses of THC are somewhat less effective than smoking and injecting, but more effective than ingesting THC because these methods all bypass the digestive system and first-pass liver metabolism. In addition, the THC metabolites stay longer in the system when consumed via these less effective routes. Because smoking may cause other side-effects from smoke exposure, these other routes of administration may be favorable where a prolonged result is desired.

THC is a highly fat soluble substance, which means that it has a preference for lipid-rich tissues such as lungs, hearts, brain, and liver (R).

Brain levels of THC are almost always higher than blood levels, and there may be THC in the brain even when it is absent in the blood. Chronic use of THC can result in THC accumulation in fat tissues (R).

THC readily crosses the placenta in dogs and sheep (R).

Clearance of THC involves CYP450 in phase II liver detoxification (R).

The Good: Health Benefits of Tetrahydrocannabinol


1) THC Benefits Cardiovascular Diseases 

Marijuana use is typically associated with other unhealthy behaviors such as a high calorie diet, smoking, and other drug use (R). However, mechanistic studies found that THC itself (without those unhealthy lifestyle factors) have shown that THC may help reduce cardiovascular disease risk.

THC Hinders Progression of Atherosclerosis Plague

Patients developing atherosclerosis or hardening of arteries have increased levels of foam cells in the major arteries which lead to deposition of cholesterol and fatty plaque (R).

CB2 receptors are present on the surface of foam cells that THC activates, preventing them from depositing fatty streaks in the heart (R, R2).

In rats, similar results were shown through supplementation of low levels THC to reduce atherosclerosis without psychoactive effects (R).

THC inhibits the 15-lipoxygenase enzyme, which is an enzyme that oxidizes low-density lipoprotein (R).

THC’s anti-inflammatory effects reduce platelet accumulation and promote immune function in the heart, which inhibits atherosclerosis (R).

2) THC May Inhibit Tumor Growth and Help Prevent Cancer 

Brain Cancer

Glioblastoma multiforme is a deadly and hard to treat form of brain cancer with limited treatment options and a low life expectancy. Direct injection of THC into the glioblastoma tumors inhibits tumor cell proliferation and increased the median life expectancy by about 24 weeks (R). A cellular study found that CBD enhances this effect of THC (R).

Breast Cancer

Treatment of breast cancer cells in mice showed that low doses THC (.5 mg/day) served significant anti-tumor properties. THC reduced growth, number, and overall blood vessel number in the breast tumors (R).

In mice, THC also successfully inhibits ErbB2-driven breast cancer through inhibition of Akt and mTOR signaling pathways (R).

However, THC use may not be beneficial in breast cancer types that do not harbor cannabinoid receptors. In addition, THC may suppress the anti-tumor immune responses (R).

Lung Cancer

THC inhibits EGF-induced lung cancer cell migration in cell lines and metastasis in mice (R).

In a survey of people who are habitual THC users but not cigarette smokers, the use of THC did not increase the incidence of lung cancer, although negative outcomes from smoking THC were not ruled out (R).

Prostate Cancer

The interplay between cannabinoid receptor and prostate cancer prognosis is complex. Some studies found that THC inhibits cell growth, while others found it enhances cell growth (R).

3) THC Stimulates Appetite and Can Help With Nausea


In patients suffering from HIV, cancer or other diseases that lead to decreased appetite and muscle wasting, THC and other cannabis substances has been studied as an effective treatment to stimulate appetite and mitigate cachexia (R).

In HIV patients, increased intake of THC through inhalation reduced the levels of peptide PYY (an appetite suppressant), while increased levels of leptin and ghrelin (R).

4) THC Helps with Pain Management

In mice, THC may have a pain relieving effect by potentiating the glycine receptor, including neuropathic pain (RR2).

However, human studies showed mixed results regarding THC’s effectiveness for pain management (R, R2).

Mice that consumed THC increased the activity CB1 receptor and release of the agmatine. The release of agmatine increased pain tolerance while also increasing overall body temperature (RR2).

Multiple Sclerosis

Oral ingestion of THC in patients suffering from multiple sclerosis (MS) reduced symptoms. The maximum dosage of 25 mg of THC over the course of 15 weeks reduced pain and muscle stiffness. Also, perceived notions of healing in patients with MS increased after taking THC, improving the quality of life (RR2R3).

5) THC Can Help Insomnia and Increase Deep Sleep

Cannabis and THC administration appears to decrease the time it takes to fall asleep and increase stage 4 sleep, but decrease REM sleep (R).

6) THC Helps Prevent Seizures 

In a rat model, THC completely abolishes epileptic seizures (R).

7) THC Increases Insulin Sensitivity

An epidemiological study found that current marijuana use is associated with 16% lower fasting insulin levels in comparison to past marijuana users and 26% in comparison to people who never used marijuana (R). This trend was also similar for other insulin resistance metrics, suggesting that THC increases insulin sensitivity.

On the other hand, in both mice and humans, blocking the cannabinoid receptor 1 increases insulin sensitivity in an adiponectin-dependent manner (RR).

8) THC Can Improve Your Brain in Some Ways

Chronic THC exposure in mice results in increased brain-derived neurotrophic factor (BDNF) in the hippocampus, but not in the frontal lobe (R).

Marijuana smoking increases cerebral blood flow both acutely and 2 hour afterwards (R, R2).

Alzheimer’s Disease

THC has been shown to reduce amyloid plague levels, reduce inflammation, and improve mitochondrial function in cellular models (R, R2).


5-HT1A agonists enhances the CB1 receptor-mediated effects of THC (R).

The Bad: Adverse Effects of THC

THC can cause schizophrenia-like symptoms, altered perception, increased anxiety, delayed recall time, impaired mental performance, and increased cortisol (R).

After ingesting a high dose of THC, increased levels of adrenaline were detected after 2 hours but then returned to normal after 4 hours (R).

Cannabinoid use can impair working memory through CB1 receptor in astroglial cells (R).

Chronic consumption of Cannabis increased the odds of getting Bipolar disorder and manic episodes (R).

THC may reversibly block synaptic neuroplasticity in the nucleus accumbens and hippocampus (R).

Chronic THC usage in humans reduces overall dopamine synthesis which in turn reduces motivation (R).

Highly potent cannabis may impair creativity and divergent thinking (R).

Repeated use of cannabis can result in tolerance due to a reduction in CB1 receptors (R).

Prior THC exposure can make nicotine more addictive in rats (R).

Technical: Actions of THC Receptors and Neurotransmitters

THC is a CB1 and CB2 partial agonists. THC binds to CB1 receptors on GABAergic and glutamatergic neurons, thus disrupting signaling systems to dopaminergic neurons (R, R2). In addition, THC allosterically modulates opioid receptors (R).

THC causes euphoric state through increasing of dopamine signaling, although chronic use of THC can blunt the dopamine receptors (coded by DRD1 and DRD2 genes) (R). The effects of THC on the dopamine system appears to be dependent on dose and duration of use (R).

When THC is present with Cannabidiol (CBD), it appears that CBD modulates the effects of THC on the CB1 and CB2 receptors (R). CBD itself is not psychoactive.

Health Tools I Wish I Had When I Was Sick

At SelfHacked, it’s our goal to offer our readers all the tools possible to get optimally healthy. When I was struggling with chronic health issues I felt stuck because I didn’t have any tools to help me get better. I had to spend literally thousands of hours trying to read through studies on pubmed to figure out how the body worked and how to fix it.

That’s why I decided to create tools that will help others cut down the guesswork:

  • Lab Test Analyzer – a software tool that will analyze your labs and tell you what the optimal values are for each marker — as well as provide you with actionable tips and personalized health and lifestyle recommendations to help you get there.
  • SelfDecode – a software tool that will help you analyze your genetic data from companies such as 23andme and ancestry. You will learn how your health is being impacted by your genes, and how to use this knowledge to your advantage.
  • SelfHacked Secrets – an ebook where we examine and explain the biggest overlooked environmental factors that cause disease. This ebook is a great place to start your journey if you want to learn the essential steps to optimizing your health.
  • SelfHacked Elimination Diet course – a video course that will help you figure out which diet works best for you
  • Selfhacked Inflammation course – a video course on inflammation and how to bring it down
  • Biohacking insomnia – an ebook on how to get great sleep
  • Lectin Avoidance Cookbook – an e-cookbook for people with food sensitivities
  • BrainGauge – a device that detects subtle brain changes and allows you to test what’s working for you
  • SelfHacked VIP – an area where you can ask me (Joe) questions about health topics

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


1 Star2 Stars3 Stars4 Stars5 Stars (14 votes, average: 4.29 out of 5)


  • FC

    Cannabinoids can contribute to Fatty Liver Disease via upregulating CB1 receptor which is causing fibrosis. Regular users may consider raw diet rich in kiwis and papayas or supplemental protease enzymes like: bromelain, serrapeptase, nattokinase, lubrokinase.

  • Mark

    Any ways to reverse brain damage from excessive cannabis use?

  • Good Guys Gardening

    Hmm. After reading this article I learned many things about cannabis. Also changed my intention about it. Thank you for the writing.

    1. Shea

      You’re welcome! Glad you learned from it. 🙂

  • Patrick

    For a long time I have wondered, is there any information out there giving a ballpark estimate of THC/CBD’s ORAC value? The only values anyone ought to trust are the ones published by the USDA. Nevertheless, in a speculative context, has anyone tried to guess? How does CBD compare to cocoa, cinnamon, or cloves?

  • carol close “The nonpsychoactive Cannabis constituent cannabidiol is a wake-inducing agent.” Lateral hypothalamus or dorsal raphe nuclei are wake-inducing brain areas which cannabidiol enhances wakefulness and decreases slow wave sleep and REM sleep. Furthermore, cannabidiol increases alpha and theta power spectra but diminished delta power spectra. Additionally, cannabidiol increases c-Fos expression in lateral hypothalamus or dorsal raphe nueclei. These findings suggest that cannabidiol is a wake-inducing compound that presumably activates neurons in lateral hypothalamus and dorsal raphe nuclei.
    (So cannabis increases alpha and theta sleep and decrease delta sleep. Delta sleep is when growth hormone and prolactin are produced. Growth hormone is essential for klotho, the anti-aging hormone.) Levels of puberty-related hormones such as testosterone and luteinising hormone (LH) were increased in the cannabis smokers. In contrast, growth hormone levels in the group were decreased.

    • Super strong cannabis responsible for quarter of psychosis cases
    • Cannabis use shrinks and rewires the brain
    • Even casual use of cannabis alters the brain
    • Cannabis can be highly addictive, major study finds

    It was also found that non-smoking boys were on average four kilos heavier and 4.6 inches taller by the age of 20 than the dope smokers.

    The researchers also looked at the effect of smoking cannabis on levels of the stress hormone, cortisol, in 10 cannabis addicts.

    They found that dope smokers have significantly higher levels of cortisol than non-smokers.

  • john mare

    regarding the schizo problem, just avoid what has more than 10% thc content. Those strains of mary jane are fine. This has also been studied.

  • Leave a Reply

    Your email address will not be published. Required fields are marked *

    This site uses Akismet to reduce spam. Learn how your comment data is processed.