CBD and THC are both compounds from the cannabis plant. THC is the one that causes the high, and CBD doesn't. The law differs by country and by US state, so check the rules where you live, and speak to a doctor first if you take any medication.
Those two short names get mixed up a lot, partly because products often contain both. CBD stands for cannabidiol and THC for tetrahydrocannabinol. They're related, but they behave differently, and the legal, workplace and labelling questions are different too. I'll keep this to what's well established and leave health claims out of it.
CBD vs THC at a glance
| CBD | THC | |
|---|---|---|
| Where it comes from | Cannabis plants, most often hemp | Cannabis plants, mostly marijuana varieties |
| Does it cause a high? | No | Yes |
| Legal status in general terms | Often allowed in some form, with limits on THC content and on how products are sold | Often restricted or illegal, with some places allowing medical or adult use |
| Drug tests | Standard tests don't look for it | Standard workplace tests look for it |
| Common forms | Oils, gummies, capsules, creams, vapes | Flower, edibles, vapes, oils, where legal |
The table is a simplification. Laws change, and a product sold as CBD can still contain some THC. That's why labels and lab reports matter, and I'll come back to them below.
How they work, in plain words
Your body has a network called the endocannabinoid system. Both CBD and THC interact with it, but in different ways. THC is known for its effect on the brain that produces the high. CBD doesn't produce that effect, and researchers are still working out exactly how it acts.
Research is still developing, so I won't claim that either compound treats or cures anything. If you're thinking about either one for a health reason, that's a conversation for a doctor or pharmacist, not a blog post.
Hemp vs marijuana
Both are the same species of plant, Cannabis sativa, but they're grown and defined differently. Hemp is the kind bred to contain very low THC, and it's the usual source of CBD products. Marijuana varieties contain much more THC. In the US, the 2018 Farm Bill made hemp with a very low THC level federally legal, but state rules still differ, and CBD products are regulated separately.
In the UK, CBD products can be sold in some forms, and edible CBD products fall under the Food Standards Agency's novel food rules. In other countries the rules change again. Check your local regulator rather than relying on a general summary.
Full spectrum, broad spectrum and isolate
You'll see these three terms on labels. They describe what else is in the product alongside CBD.
- Full spectrum: contains CBD plus other plant compounds, which can include a small amount of THC.
- Broad spectrum: contains CBD plus other plant compounds, with the THC removed or reduced as far as the maker can manage.
- Isolate: contains CBD on its own, in purified form.
Which you pick matters if you're drug tested or want to avoid THC completely. It's the first thing to check on the label.
Can CBD make you fail a drug test?
Standard workplace drug tests look for THC or its by-products, not CBD. The risk comes from THC that can sit in a product. Full spectrum products can contain a small amount, and some products turn out to contain more than the label says. Regular use may allow even small amounts to build up in your system.
If you're tested at work, talk to your employer before you use any cannabis-derived product. This guide is a general overview, and I can't tell you what your own test will find.
If avoiding THC matters to you, isolate is the lowest-risk choice on paper, and a broad spectrum product comes next. Even then, rely on the lab report for that batch rather than the wording on the front, because marketing terms aren't tightly standardised.
Reading a CBD label
Labels can be vague and quality varies, so a few checks are worth the time.
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- Third-party lab report: look for an independent test, often called a certificate of analysis, that you can read.
- Batch number: the report should match the batch on your bottle or packet.
- THC content: check what the report says about THC, not just the front of the pack.
- Ingredients: make sure you know what else is in it, including carrier oils, sweeteners and flavours.
- Dose per serving: it should be clear, so you know how much you're taking.
- The seller: a company that makes testing easy to find is a better sign than one that hides it.
Be wary of products that make health promises. In many places it's against the rules for sellers to claim a CBD product treats or cures a condition, and a company that does so is not one I'd trust with your attention. A trustworthy seller sticks to what the product is, what's in it and how it was tested.
Medication interactions
This is the part to take seriously. CBD can interact with some medicines, because it may change how the body processes them. Regulators have warned about this. The only CBD medicine approved by the US Food and Drug Administration is Epidiolex, which is prescribed for certain rare seizure conditions. That approval doesn't apply to over-the-counter CBD products.
If you take any prescription or over-the-counter medicine, speak to a doctor or pharmacist before trying CBD. Tell them exactly what product you're considering. If you're pregnant, breastfeeding or have a health condition, ask first as well.
Rules about CBD also vary on travel. A product that's fine at home may be restricted in another country or state, so check before you pack it. Airlines and border agencies can have their own rules too.
For brands and writers
If you run a CBD business and want to share your expertise, here's how to write for my CBD section. If you work with cannabis-related brands, my notes on marketing tactics for cannabis businesses may help too.
This is general information, not medical or legal advice. Check the law where you live and speak to a doctor before using CBD, especially if you take any medication.
Frequently asked questions
What is the main difference between CBD and THC?
Both come from the cannabis plant, but THC causes a high and CBD doesn't. They're also treated differently by law and by workplace drug tests.
Is CBD legal?
It depends on where you live. Many places allow CBD with limits on THC and on how products are sold, but the rules change, so check your local regulator.
Does CBD show up on a drug test?
Standard tests look for THC, not CBD. Some CBD products contain a small amount of THC, so talk to your employer before using one if you're tested.
Can I take CBD with my medication?
Not without checking. CBD can interact with some medicines, so speak to a doctor or pharmacist first.
