CBD vs THC: Understanding the Difference

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Introduction

If you’re exploring medicinal cannabis as a treatment option, you’ve likely encountered the terms CBD and THC. These two cannabinoids are the most well-known compounds found in the cannabis plant, but they have very different effects on the body and mind .

At Auscare Store, we believe in empowering Sydney patients with accurate, educational information about medicinal cannabis. This guide explains the key differences between CBD and THC, how they work, and what conditions each may be used for under medical supervision.

Important: This information is for educational purposes only. Medicinal cannabis products require a valid prescription from a registered medical practitioner and are only available to eligible patients through TGA-approved pathways .

What Are Cannabinoids?

Cannabinoids are natural chemical compounds found in the Cannabis sativa plant. The cannabis plant produces between 80 and 130 different cannabinoids, plus around 300 non-cannabinoid chemicals . The two main cannabinoids used in medicinal cannabis products are:

Cannabinoid	Full Name	Key Characteristic
THC	Delta-9-tetrahydrocannabinol	Psychoactive—produces a “high”
CBD	Cannabidiol	Non-psychoactive—does not produce a “high”

While THC and CBD have similar chemical structures, they differ dramatically in their mechanisms of action and effects on brain function .

🧠 How They Work: The Endocannabinoid System

To understand CBD and THC, you first need to know about the endocannabinoid system (ECS) — a unique communications system in the brain and body that affects many important functions including:

Mood
Memory
Sleep
Appetite
Pain sensation

The ECS is made up of natural molecules (endocannabinoids) and the receptors they interact with. It’s thought that medicinal cannabis can treat various illnesses by acting on this system .

How THC Works

THC acts on specific receptors in the brain known as cannabinoid or CB1 receptors. This binding action is what gives THC its psychoactive effects the feeling of being “high.” THC has a high affinity for these receptors, which is why its effects are so noticeable .

How CBD Works

CBD, by comparison, has less affinity for CB1 and CB2 receptors. Instead, it works to partly block receptor activity and inhibits the uptake of anandamide (an endocannabinoid), thus increasing its concentration in tissues . CBD has also been identified as a serotonin receptor (5-HT1A) agonist, which may be the basis of its purported anxiolytic (anti-anxiety) and antipsychotic actions .

⚡ Key Differences at a Glance

Feature	THC	CBD
Psychoactive	Yes—produces a “high”	No—does not produce a “high”
CB1 Receptor Affinity	High	Low (acts as antagonist)
Common Uses	Pain, nausea, muscle spasms, appetite stimulation	Seizures, anxiety, inflammation, psychosis
Side Effects	Euphoria, drowsiness, confusion, anxiety (at high doses)	Generally well-tolerated; mild drowsiness, appetite changes
Driving Impact	May cause positive roadside drug test	No evidence of driving impairment
Legal Status (Australia)	Schedule 8 (controlled drug)	Schedule 4 (prescription only) or Schedule 3 (pharmacist-only for low-dose)

💊 Therapeutic Uses: THC vs CBD

THC (Tetrahydrocannabinol)

THC is the chemical responsible for the psychotropic effects of cannabis and is the reason cannabis is used recreationally . However, THC also has significant therapeutic properties:

Condition	Evidence
Chronic pain	Effective at relieving chronic pain, particularly neuropathic (nerve) pain
Chemotherapy-induced nausea and vomiting	Evidence supports use after standard treatments have failed
Multiple sclerosis spasticity	Some evidence for pain and spasticity symptoms
Appetite stimulation	May improve appetite in palliative care
Sleep	May improve sleep in certain conditions

A Canadian retrospective cohort study found that increased THC:CBD ratio was associated with greater response for:

Neuropathic pain (odds ratio: 3.58)
Insomnia (odds ratio: 2.93)
Depressive symptoms (odds ratio: 1.63)

CBD (Cannabidiol)

CBD has medicinal properties but cannot make the user feel ‘high’ . It has been the subject of increasing research interest:

Condition	Evidence
Epilepsy	CBD reduces seizure frequency in Dravet syndrome and Lennox-Gastaut syndrome . Epidyolex (CBD) is TGA-approved and PBS-listed for these conditions .
Anxiety	May have anxiolytic effects through 5-HT1A receptor activity
Psychosis	Emerging evidence for antipsychotic effects
Inflammation	CBDA (CBD acid) appears promising as an anti-inflammatory substance
Pain	Evidence less robust than THC; may work best in combination with THC

Important: A study into fibromyalgia pain showed that the combination of CBD and THC had better effect on pain reduction than THC alone. Conversely, CBD alone had no effect on pain .

The Ideal THC:CBD Ratio

One of the most common questions patients ask is: “What THC:CBD ratio is right for me?”

The answer depends entirely on your condition, symptoms, and individual response. Research suggests:

Ratio	Best For
High THC, Low CBD	Neuropathic pain, insomnia, nausea, appetite stimulation
1:1 Balanced (50% THC, 50% CBD)	Anxiety symptoms—showed an inverted U-shaped curve with maximal benefit at this ratio
High CBD, Low THC	Epilepsy, anxiety (without psychoactive effects), patients sensitive to THC
CBD Only	Childhood epilepsy, patients who cannot tolerate any psychoactive effects

However, it is still difficult to say which THC:CBD ratio is the most ideal for a specific medical condition, as individual responses vary . The ultimate medicinal effect of cannabis does not depend solely on CBD or THC terpenes (aromatic compounds) also play a role in what is known as the “entourage effect” .

Important: CBD, THC and Driving

This is a critical consideration for Australian patients:

THC: In all Australian states and territories except Tasmania, it is unlawful to drive with any detectable THC in your system even if prescribed for medicinal purposes. There is no medical defence.
CBD: Studies have found no evidence that CBD negatively affects driving behaviour on its own . However, when using CBD and driving, it is important to avoid combining CBD with THC, as THC-containing products will show up on roadside drug tests.

Side Effects

Common Side Effects of THC

Drowsiness and sedation
Dizziness
Confusion
Anxiety and paranoia (at high doses)
Dry mouth
Increased appetite
Memory impairment

Common Side Effects of CBD

CBD is generally well-tolerated. Possible side effects include:

Sleepiness / drowsiness
Changes in appetite
Diarrhoea
Fatigue
Irritability
Elevated liver enzymes (with high doses, requires monitoring)

CBD may also cause side effects if it interacts with other medicines . There are significant interactions between CBD and anti-seizure medications including sodium valproate, clobazam, and lamotrigine .

Legal Status in Australia

THC-Containing Products

Schedule 8 (controlled drug)
Prescription-only
Stricter regulatory controls
Requires TGA approval (SAS or Authorised Prescriber)

CBD-Only Products

Schedule 4 (prescription only) for most products
Schedule 3 (pharmacist-only) for low-dose CBD (≤150mg daily dose, ≥98% CBD, <1% THC)
Available by prescription or (for low-dose) from pharmacists after consultation

Both THC and CBD products must be prescribed by a registered medical practitioner. Patients cannot personally import medicinal cannabis products .

Forms of Medicinal Cannabis

Medicinal cannabis products come in many forms :

Form	Typical Use
Oils	Most common; taken orally, precise dosing
Capsules	Convenient, consistent dosing
Dried flower	For vaporisation only (smoking not recommended)
Oro-mucosal sprays	Fast absorption under the tongue
Topicals	Creams and balms for localised relief

Note: Smoking medicinal cannabis is not recommended by health authorities. It’s difficult to track dosage and smoking damages the lungs

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