Delta-8 and Delta-9 THC: What's the Difference?

In the field of endocannabinoid medicines, you may have heard of two forms of THC known as delta-8 and delta-9 tetrahydrocannabinol (THC) compounds (hereto referred to as “delta-8” and “delta-9”). So, what is the difference between these two compounds?

What’s the Difference Between Delta-9 and Delta-8 Molecules?

Both delta-9 and delta-8 molecules are derived from marijuana. Delta-9 is the more famous of the cannabinoid THC molecules. Delta-9 THC is known for its psychoactive (“getting high”) effects and is often referred to as “THC.” Delta-9 is derived from its parent compound, the “mother of all cannabinoids,” cannabigerol (CBG—see diagram).

Source: Dr. Peter Bongiorno

Delta-8 is a metabolite of delta-9 and is naturally available from cannabis in low quantities. Commercially sold since 2018, delta-8 is available to consumers because it can be synthesized from hemp-derived cannabidiol (CBD) through a synthetic cyclization process. This process uses several different chemicals to create delta-8 from CBD. Hemp is a different plant from marijuana and contains minimal and nonpsychoactive levels of delta-9 THC but can be used to make delta-8 THC because it has abundant amounts of CBD.

Delta-8 and delta-9 are nearly identical molecules (save one difference in the location of a double bonding of shared electrons). Both delta-8 and delta-9 THC molecules can bind to endocannabinoid receptors CB1 (mostly in the brain’s central nervous system) and CB2 (mostly in the rest of the body) to create a psychoactive effect.

Both delta-9 and delta-8 are potent psychoactive substances. However, delta-8 has garnered interest because some states restrict delta-9 while still allowing delta-8 to be sold legally, as it is naturally derived from CBD extracted from hemp. This is a result of the Agriculture Improvement Act of 2018, known as the "Farm Bill," which permitted the sale of hemp products containing less than 0.3 percent delta-9 THC while still prohibiting marijuana products with significantly higher levels of delta-9 THC. Consequently, delta-8 products, including gummies, vapes, and combustible flowers, have surged in popularity, offering a promise that delta-8 provides a similar "high" as its more famous delta-9 counterpart for those unable to legally purchase delta-9 products.

Dirty Delta-8?

Many doctors believe that delta-8 is a "dirty" cannabinoid. The concern regarding delta-8 THC lies in its unregulated synthesis and production. Consequently, consumers may find it difficult to determine if it is contaminated with other substances or contains elevated levels of toxins resulting from the synthetic processes used to create the drug. Additionally, due to its legality in more areas than marijuana, there are worries that it will introduce the same health risks associated with marijuana to a larger portion of the population. This appears to be substantiated. A 2024 study published in the Journal of the American Medical Association (JAMA) indicates that 11 percent of 12th-graders have used delta-8. Moreover, delta-8 use was predictably higher in states lacking marijuana regulations, particularly in Southern and Midwestern regions. Because these molecules share similar structures, both delta-8 and delta-9 will yield positive results on drug screenings.

Drug Interactions With THC

If a patient is taking medications, it is important to be very careful with interactions that can occur with marijuana as well as any other THC products.

There are drugs that enhance the effects of marijuana and THC. THC is metabolized by the CYP3A4 and CYP2C9 cytochromes, which are specialized proteins in the liver that detoxify drugs and toxins. Drugs that inhibit these enzymes, such as ketoconazole, verapamil, fluoxetine, and amiodarone, can significantly elevate the levels and effects of THC. Cannabinoids that contain THC can also modify the effects of other medications. When THC is present alongside the anticoagulant warfarin, documented increases in bleeding issues have been noted.

Additionally, THC can enhance the effects of various medications. Using THC in conjunction with benzodiazepines and other central nervous system depressants, including alcohol, might cause drowsiness and balance issues. Sympathomimetics are medications that can activate the sympathetic nervous system—the part of our nervous system responsible for stress responses. THC can intensify the effects of sympathomimetic prescription drugs like alpha- and beta-agonists (such as clonidine and albuterol), recreational drugs like MDMA, and even over-the-counter sympathomimetics like pseudoephedrine, commonly used for cold and allergy relief. When sympathomimetic drug levels rise, individuals may encounter a rapid heartbeat, anxiety, and an elevated risk of arrhythmias or even heart attacks. Additionally, THC can increase the effects of anticholinergic medications such as those for Parkinson's disease, the anti-nausea drug Dramamine, antihistamines like Benadryl, and cold symptom medications like Dimetapp. Elevated levels of anticholinergics can result in a rapid heartbeat, blood pressure issues, urinary retention, and even central nervous system depression.

Finally, THC may reduce the effects of theophylline (a drug used for asthma and lung issues), as well as clozapine and olanzapine (medications for schizophrenia), which could result in a return of symptoms because the medication is not as effective.

Take a Break, Delta-8

Adolescents should refrain from using THC products, or marijuana, unless used for bona fide medical purposes under the care of a health practitioner. It is well established that teens who consume marijuana can experience arrested brain development in the prefrontal cortex, which increases the risks of cognitive dysfunction, mood disorders, and accelerated brain aging later in life. Since brain development is not complete until age 26, I believe that individuals under 26 should not regularly use these products unless directed by a medical practitioner for necessary treatment. Those over 26 should also exercise caution; like other addictive and mind-altering substances, they certainly should avoid daily use of delta-8 or THC products.

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Consumers who decide to use commercially available delta-8 products should verify their quality by researching the manufacturer. As consumers, we can ask for quality control information such as certificates of analysis (COAs). Any reputable company should be happy to share these with their customers.

Finally, consumers of these products should also reflect on their reasons for using them. While there may be short-term benefits and minimal harm to some individuals from using substances recreationally, chronic use indicates that there may be underlying issues that need to be addressed.