CBD vs THC: The Complete Guide — How They Work, What They Do, and Why One Gets You High (And The Other Doesn’t)

Cannabis has become one of the most talked-about plants in modern wellness. But two of its best-known molecules — CBD (cannabidiol) and THC (tetrahydrocannabinol) — are often confused. They come from the same species, yet they behave very differently in the body. This guide explains everything your customers need to know: the science, the practical effects (smoking, vaping, topical use), the legal picture in the UK, and real-world UK case studies so your audience can make thoughtful, safe choices.

Quick snapshot

• THC = psychoactive; it binds to brain CB1 receptors → gets you high.

• CBD = non-psychoactive (does not produce a high); it modulates the endocannabinoid system (ECS) and has anti-inflammatory, antioxidant and balancing effects.

• Topical CBD works locally on the skin and won’t get you high.

• Certain CBD and THC medicines are prescribed in the UK for specific conditions (epilepsy, MS spasticity) under strict regulation.

What are CBD and THC?

Both CBD and THC are phytocannabinoids — plant compounds found in Cannabis sativa. There are over a hundred cannabinoids, but THC and CBD are the most widely studied.

• THC (Δ9-tetrahydrocannabinol): the principal psychoactive ingredient. It produces euphoria, altered perception, and can impair coordination and memory.

• CBD (cannabidiol): non-intoxicating at normal doses. It doesn’t produce a “high” and is used for calming, anti-inflammatory and potential anticonvulsant effects.

Why the confusion? Hemp and marijuana are both types of Cannabis sativa. Hemp varieties typically have very low THC (legally required to be below a set threshold) and can be CBD-rich. Consumers often see similar packaging and scents and assume equivalence; the chemistry, however, matters.

Section 2 — How they act in the body: the Endocannabinoid System (ECS)

The endocannabinoid system (ECS) is a regulatory network found throughout the body. It helps keep biological processes in balance — mood, sleep, appetite, immune activity and skin homeostasis.

Key parts of the ECS:

• Endocannabinoids (naturally produced by our bodies) such as anandamide.

• Receptors: chiefly CB1 (abundant in the brain and nervous system) and CB2 (more in immune cells and peripheral tissues, including skin).

• Enzymes that make and break down endocannabinoids.

THC behaves like an endocannabinoid and binds directly to CB1 receptors in the brain — that direct activation is what causes intoxication and the classic “high”.

CBD doesn’t bind strongly to CB1. Instead it modulates multiple parts of the ECS and other receptor systems (serotonin receptors, TRPV channels, and enzymes). It helps the body use its own endocannabinoids more effectively and has anti-inflammatory and neuromodulatory effects without producing euphoria.

(For a simple visual comparison of how CBD and THC interact with CB1 and CB2, see the chart: “THC vs CBD: Interaction with ECS components (illustrative)” below.)

Cited UK-relevant evidence: UK and international clinical practice recognise CBD-based medicines for seizures and THC/CBD sprays (nabiximols/Sativex) for MS spasticity, demonstrating how different cannabinoids are evaluated and used medically. Epilepsy Action+1

Receptor interactions

Smoking or vaping CBD vs THC: what actually happens?

Smoking and vaping deliver cannabinoids rapidly to the bloodstream. The differences are mostly about psychoactivity and side effects.

THC (smoked/vaped)

• Onset: within minutes.

• Peak: quick (minutes to half an hour).

• Effects: euphoria, altered perception, increased appetite, impaired reaction times; can cause anxiety or paranoia in some people.

• Risks: lung irritation (smoking), impaired driving, short-term memory effects, and potential for problematic use with heavy long-term consumption.

CBD (smoked/vaped)

• Onset: also rapid when inhaled, because absorption is quick.

• Effects: calming, anti-anxiety for some people; does not cause intoxication or the classic “high.”

• Risks: lung irritation with smoking; vaping oils must be high quality and pure — contaminated cartridges have caused harm in the past.

Onset & Duration: inhalation produces fast onset but variable duration compared with oral routes. See the illustrative chart below for typical onset/duration differences by administration route.

Important note on CBD “flower” or hemp flower: some vendors sell hemp flower that smells and looks like marijuana but meets legal THC limits (often below 0.2% in the UK/EU). That trace THC is unlikely to produce intoxication, but lab testing is essential.

Oral vs sublingual vs topical: practical differences

• Oral (edibles, capsules):

  • Slower onset (usually 30–120 minutes); longer duration (several hours).

  • Oral THC undergoes first-pass metabolism and can create stronger, longer-lasting intoxication for the same dose compared with inhalation.

• Sublingual (oils/tinctures):

  • Faster absorption than oral; often used for more predictable dosing.

• Topical (creams, balms):

  • Local effects on skin or soft tissue: anti-inflammatory, antioxidant, moisturising.

  • Topical CBD does not reach the brain or cause a high in normal cosmetic or therapeutic use; systemic absorption is minimal. This makes CBD topicals attractive for skin inflammation, arthritic joints, or local muscle soreness.

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CBD and skincare: what does the evidence say?

Topical CBD has gained traction in cosmetics and dermatology because of its anti-inflammatory and antioxidant properties. Preclinical and early clinical literature suggests CBD can:

• Reduce inflammatory cytokines implicated in acne and eczema.

• Suppress sebocyte (skin oil gland) overactivity — a potential anti-acne mechanism.

• Provide antioxidant protection that may help ageing skin.

A 2022 systematic review and multiple recent reviews summarise CBD’s anti-inflammatory and anti-acne potential (laboratory and early human studies). While promising, large, rigorous RCTs on topical CBD for specific skin diseases are still evolving; nano-formulations and delivery technology are active research areas. PMC+1

Practical takeaways for skincare brands and customers

• Use well-formulated, lab-tested topical products. CBD performs best when paired with skin-healthy oils, antioxidants and stable preservatives.

• Look for CPSR/regulated cosmetic documentation and 3rd-party lab results (heavy metals, pesticides, residual solvents, cannabinoid profile). Highly Enfused products are CPSR-certified and use organic ingredients, which helps reassure customers. (Keep certificates accessible on product pages.)

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Benefits and side effects: the big comparison

Below is a concise comparison of typical benefits and adverse effects.

Benefits

• CBD: anti-inflammatory, anxiolytic effects in some studies, anticonvulsant (for certain syndromes), promotes skin calm and antioxidant protection. Epilepsy Action+1

• THC: potent analgesia for some conditions, appetite stimulation, muscle spasm reduction (particularly when combined with CBD in medicinal sprays like Sativex). PubMed

Common side effects (illustrative)(See downloadable chart showing approximate relative frequencies.)

• THC: dry mouth, red eyes, increased appetite, dizziness, anxiety/paranoia in some people.

• CBD: generally well tolerated; possible drowsiness, dry mouth, and interactions with other medications (important to check with a clinician).

Side effects frequency

Safety, drug interactions and lab testing

Drug interactions: CBD can interact with medications metabolised by the liver’s cytochrome P450 enzymes (CYPs). That’s the same enzyme family involved with many prescription drugs. For customers on prescription medicines (especially blood thinners, certain antiepileptics), advise consulting a clinician before starting CBD.

Quality matters

• Look for third-party lab testing showing CBD concentration, THC < legal limit, absence of contaminants.

• Avoid unregulated vaping cartridges or unlabelled products. Use trusted suppliers.

Topical safety Topical CBD products generally have low systemic absorption and are safer regarding drug interactions, but patch testing is sensible (especially for sensitive or eczema-prone skin).

Legal status in the UK (short version)

• CBD derived from hemp with very low THC content is legal and widely available as a cosmetic ingredient in the UK when compliant with cosmetic regulation and CPSR listing.

• THC (psychoactive) remains controlled and is not legal for general sale. Specific, licensed medicinal products that contain THC (or THC+CBD) may be prescribed in limited circumstances under medical supervision. Sativex (nabiximols) is one such licensed product for MS spasticity; Epidyolex (a purified CBD pharmaceutical) is licensed for specific epilepsies. Epilepsy Action+1

UK case studies and clinical evidence (what happened here at home)

Below are several UK-relevant studies and outcomes that should be quoted in the blog to give readers evidence grounded in British practice and research.

1. Epidyolex (CBD) — licensed for rare epilepsy syndromes

Epidyolex (a pharmaceutical, purified CBD formulation) has been approved and recommended for specific severe epilepsy syndromes (Dravet syndrome and Lennox-Gastaut) and listed for use in NHS practice for qualifying patients. This highlights CBD’s proven anticonvulsant properties in specific populations under medical supervision. Epilepsy Action+1

2. Sativex (nabiximols) — THC+CBD oromucosal spray for MS spasticity

Sativex, an oromucosal spray containing roughly equal amounts of THC and CBD, has clinical trial evidence showing reduced spasticity in people with multiple sclerosis; the UK has approved it for certain patients and it is part of NHS-available treatments in qualifying circumstances. This showcases how THC+CBD combinations can be useful therapeutically under strict protocols. PubMed+1

3. UK Medical Cannabis Registry cohort studies — real-world data

Analyses from the UK Medical Cannabis Registry (cohort studies) have reported improvements in symptoms like anxiety and quality of life for some patients prescribed cannabis-based medical products (CBMPs). These registry data are valuable real-world evidence but are observational — they indicate potential benefits and safety signals that require further RCT confirmation.

4. Ongoing and new NHS trials (2025)

The NHS and UK universities are expanding clinical trials on cannabis medicines, including trials planned to start in 2025 for refractory epilepsy that will evaluate both CBD and THC containing products. This shows the UK research community is actively trying to produce higher-quality evidence. Epilepsy Action

5. CBD in dermatology (reviews & lab studies)

Multiple reviews and preclinical studies (including recent systematic reviews) indicate CBD’s anti-inflammatory and anti-acne potential. While lab data and early human studies are favourable, large clinical trials for common dermatological conditions remain limited and are a field of active research.

Practical guidance (How to choose, use and store CBD products)

1. Check certificates — Product must have third-party lab results (COA) for cannabinoid profile and contaminants.

2. THC limits — In the UK/EU, legal CBD products should contain only trace THC (commonly <0.2% in many jurisdictions; always check current legal thresholds and product COAs).

3. Topicals for skin — Choose creams and balms with good emollients, stable formulations and clear lab tests. Avoid products claiming miraculous cures.

4. Start low, go slow — For oral or sublingual use, start with a low CBD dose and increase gradually while monitoring effects.

5. Check interactions — If on medicines, advise customers to consult a pharmacist or doctor.

6. Storage — keep cool, out of direct sunlight; oils and creams last longer when stored properly.

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Frequently asked questions (FAQ)

Q — Will CBD in a cream get me high? A- No. Topical CBD is not absorbed into the bloodstream at levels that cause intoxication in normal cosmetic or therapeutic use.

Q — If CBD products smell like weed, do they contain THC? A — Hemp and cannabis share terpenes that give characteristic aromas. A smell alone doesn’t mean high THC — always check lab reports.

Q — Are CBD products safe during pregnancy or breastfeeding ?A — There isn’t robust evidence to prove safety; most clinical guidance is to avoid cannabinoids during pregnancy or breastfeeding. Encourage customers to check with healthcare providers.

Q — Can CBD show up on a drug test? A — Pure CBD should not cause a positive test for THC, but low levels of THC in full-spectrum products could, in rare cases, result in trace positive tests over time. Recommend THC-free (broad-spectrum or CBD isolate) products if drug testing is a concern.

Section 12 — Final thoughts and brand positioning

CBD and THC are cousins in the cannabinoid family but they play very different roles. CBD is your ally for everyday balance, skin calm and gentle support; THC is a powerful psychoactive agent that has therapeutic roles but also carries greater risks and legal controls.

At CBD Healing Bar we only use Highly Enfused products, we choose transparency: crafted, organic formulations, CPSR compliance, and open lab reporting so customers can see what’s in the jar. Our topical CBD balms and face masks aim to soothe and restore skin without the complications of intoxication — making natural care that’s safe, honest and effective.