CBD vs THC – What’s the difference?

Marie Law Alphabiolabs

By Marie Law, Head of Toxicology at AlphaBiolabs
Last reviewed: 02/27/2023

Cannabidiol (CBD) and tetrahydrocannabinol (THC) are chemical compounds found in marijuana and derived from the Cannabis sativa plant.

While both are classed as cannabinoids, there are some fundamental differences between the two.

Here, we explore CBD and THC, how the two are different, and the side effects of using each substance.

What is THC?

Tetrahydrocannabinol (THC) is a chemical compound and the main psychoactive ingredient found in marijuana.

This means that THC is responsible for the ‘high’ that people experience when using marijuana.

It is most commonly ingested by smoking marijuana. However, some people also vape it using electronic cigarettes, or infuse it into food or drinks including cookies, cakes, and tea.

Food and drinks that contain marijuana are known as ‘edibles’ or ‘marijuana edibles’.

What is CBD?

Cannabidiol or CBD, is a chemical found in marijuana.

However, unlike marijuana, CBD produces few if any psychoactive effects. This is because CBD only contains small amounts of tetrahydrocannabinol (THC) – the psychoactive ingredient in marijuana.

It is typically sold online, by pharmacies and by specialist retailers in the form of CBD oil but can also be found in the form of liquid, capsules, and gummies.

The purchase and sale of CBD products is legal at a federal level, provided products are hemp-derived and contain less than 0.3% THC. However, this varies from state-to-state, with some states considering the use or possession of any marijuana (cannabis) product illegal.

This means it is important to know the law for CBD in the state in which you reside.

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What are the differences in chemical composition between THC and CBD?

Although both CBD and THC are cannabinoids derived from the Cannabis sativa plant, each has a different composition.

Each shares the same molecular structure but the atoms within them are arranged differently. This means that CBD and THC have different effects on the body.

For example, THC is the main psychoactive ingredient found in marijuana, and is responsible for the physical and psychological side effects people experience when they take marijuana.

When a person uses marijuana, THC binds to specific receptors in the brain. In many people, this produces a sense of euphoria.

In contrast, CBD binds very weakly if at all to the brain’s receptors, meaning that it produces few if any psychoactive effects.

What are the medical benefits of CBD?

Advocates of CBD claim that it can be used to alleviate the symptoms associated with common conditions including anxiety, mild to moderate pain, and insomnia.

However, research is still being undertaken to determine how CBD might be used as a treatment for other conditions including Parkinson’s disease, schizophrenia, diabetes, and multiple sclerosis.

There is currently only one prescribed CBD product that has been approved for use by the Food and Drug Administration – Epidiolex – which is approved to treat seizures caused by certain types of epilepsy.

What are the medical benefits of THC?

Although some states have legalized marijuana for medical and/or recreational purposes, it remains illegal at a federal level, and is not approved by the Food and Drug Administration (FDA) for use in clinical treatments.

However, certain drugs containing small amounts of tetrahydrocannabinol (THC) – the psychoactive compound in marijuana/cannabis – are prescribed in medical settings for the treatment of certain conditions.

These drugs include:

  • Marinol – synthetic THC in a capsule form, which can be prescribed to control nausea and vomiting in chemotherapy patients
  • Epidoloex – an oral solution containing no more than 0.1% THC and used to treat two types of epilepsy
  • Syndros – an oral THC solution used in the treatment of anorexia

What are the side effects of CBD and THC?

Because THC and CBD have different chemical compositions, the side effects of each are also different.

People who use marijuana – which contains a higher concentration of THC than CBD – have been known to experience side effects including:

  • Increased heart rate and low blood pressure
  • Problems with coordination
  • Red eyes
  • Dry mouth
  • Anxiety and distress
  • Memory loss and confusion
  • Seizures

Regular ingestion of THC (via marijuana) over a prolonged period has been linked to many other long-term physical and psychological effects.

It is also important to note that the side effects of marijuana can vary considerably and can be much more harmful, depending on the strain of the drug. This is because some strains of marijuana contain much higher levels of THC than others.

In contrast, CBD products that are hemp-derived and contain less than 0.3% THC are generally considered safe and are legal at a federal level.

However, the legal status of CBD varies from state-to-state, and CBD itself still has the potential to cause adverse physical side effects, depending on how much a person uses, and whether they are taking CBD at the same time as other over the counter or prescription medications.

Some known side effects of CBD use include:

  • Dry mouth
  • Reduced appetite
  • Fatigue
  • Stomach issues
  • Dizziness
  • Nausea
  • Drowsiness

Excess use of CBD has also been linked to an increased risk of liver damage and can interfere with the effects of some prescription medications.

If you are considering taking CBD for medicinal purposes, it is recommended that you speak to your physician in the first instance, especially if you are already taking prescribed medications.

Is THC legal in the US?

THC is the main psychoactive ingredient found in marijuana.

Marijuana is a Schedule I substance under the Controlled Substances Act, meaning it remains illegal at a federal level due to its potential for abuse and dependency.

However, some states have legalized marijuana for medicinal and/or recreational purposes.

Is CBD legal in the US?

The sale of CBD was effectively legalized at a federal level in 2018, with the passing of the Agriculture Improvement Act (2018 Farm Bill), which removed hemp from the federal Controlled Substances Act.

This made hemp-derived CBD products legal with the added stipulation that they must contain less than 0.3% tetrahydrocannabinol (THC) – the psychoactive ingredient found in the Cannabis sativa plant.

However, despite this ruling, it is important to note that the legalization of CBD varies from state-to-state.

Some states consider possession of any marijuana (cannabis) products illegal, while others only permit the use of CBD when prescribed by a physician for the treatment of specific conditions.

This means it is important to understand the law in your state before purchasing CBD products.

Where can I buy a drug test?

AlphaBiolabs offers two types of home drug tests, designed to give you peace of mind or enable you to seek support for a loved one who is struggling with substance misuse.

  • Home Urine Drug Test Kit (pack of 3 – $34.95) – this easy-to-use home drug testing kit can detect drugs and their metabolites in a urine sample. The self-contained screening kit includes built-in test strips, allowing you to read the results in just 5 minutes
  • Drug and Alcohol Nail Test (from $99) – this test can detect drug use for a period of up to 12 months prior to samples being collected, with only a sample of fingernail clippings or toenail clippings required. Simply follow the instructions included in your test kit to collect your nail clipping samples and return them to our accredited laboratory for testing

Please be aware that our home drug test kits are for peace of mind only, and the results cannot be used in court or for legal reasons.

For confidential advice about which test might best suit your needs, you can email our Customer Services team at info@alphabiolabsusa.com.

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Marie Law AlphaBiolabs

Marie Law

Head of Toxicology at AlphaBiolabs
A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team. As Head of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public and the legal sector.

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