Getting Started

01What cannabis actually is

Cannabis is a flowering plant in the Cannabaceae family. It produces more than 100 distinct compounds called cannabinoids, plus dozens of aromatic compounds called terpenes. The plant you buy at a dispensary is a specific variety bred over decades for a specific ratio of those compounds — the way a Cabernet Sauvignon grape is a specific variety of Vitis vinifera bred for a specific wine.

The two cannabinoids most people have heard of are THC (tetrahydrocannabinol) and CBD (cannabidiol). They do very different things. THC is the compound responsible for the feeling of being high. CBD is not intoxicating on its own, but it changes how your body responds to THC and has its own direct effects on pain, anxiety, and seizure thresholds.

Everything else you'll see on a label — minor cannabinoids like CBG, CBN, CBC, and terpenes like myrcene, limonene, pinene, caryophyllene — is meaningful, but in smaller ways. If you understand THC and CBD, you understand 80% of what's important.

02The endocannabinoid system, in 400 words

Your body already makes its own cannabinoids. They're called endocannabinoids — endo for endogenous, meaning made inside you — and they regulate sleep, mood, appetite, pain signaling, immune response, and a half-dozen other things that all need to stay in balance.

They work on two main receptor types: CB1 and CB2. CB1 receptors are concentrated in the brain and nervous system — they're why THC feels the way it does. CB2 receptors are concentrated in immune tissue — they're why cannabis has anti-inflammatory effects that don't require feeling high.

When you use cannabis, the plant's cannabinoids dock onto the same receptors your body's cannabinoids use. THC fits well into CB1. CBD does something more indirect — it doesn't dock strongly at either CB1 or CB2, but it changes how they respond to the cannabinoids around them, and it shifts the enzymes that break cannabinoids down.

That's the 90% version. The 10% that pharmacists care about is that every person has a slightly different baseline — how many CB1 receptors you have, how efficiently your enzymes clear cannabinoids out, how sensitive your nervous system is to small shifts — and that's why two people can take the same dose and have genuinely different experiences. It's not weakness or tolerance. It's biochemistry.

03THC and CBD: the minimum you need

THC is the intoxicating compound. It relieves pain, reduces nausea, stimulates appetite, and produces the altered cognition most people think of as 'being high.' Its dose-response curve is biphasic — small amounts often reduce anxiety, but larger amounts can increase it. This is why more is frequently worse, not better.

CBD is not intoxicating. It reduces anxiety, acts as an anticonvulsant (it's the active ingredient in the FDA-approved seizure drug Epidiolex), and has anti-inflammatory effects. It also modulates how THC feels — products with a balanced CBD:THC ratio are usually gentler than pure-THC products at equivalent doses.

A useful mental model: if THC is the accelerator, CBD is the governor. Products that pair them tend to be more predictable. Products that are near-pure THC can produce the strongest effects but also the strongest side effects — cognitive fog, rapid heart rate, paranoia — especially in patients new to cannabis.

04Terpenes — the part the industry oversells

Terpenes are aromatic compounds — they're why one strain smells like pine and another like citrus. They exist in almost every plant on Earth; cannabis isn't special in producing them.

What makes them useful in cannabis is that they subtly modulate the experience of cannabinoids. Myrcene tends to feel more sedating, limonene more uplifting, caryophyllene more anti-inflammatory. The effect sizes are real but small relative to THC and CBD content. Any budtender who tells you a specific terpene profile will treat a specific condition is overselling — the research doesn't support claims that strong.

A pharmacist's rule of thumb: treat terpene dominance as a tiebreaker between two products with similar cannabinoid profiles, not as the main factor in picking a product.

05A short honest history

Cannabis has been used medicinally for at least two thousand years. It appears in the Chinese pharmacopoeia Shen Nong Ben Cao Jing, in the writings of Ibn al-Baytar, in the formularies of medieval Islamic medicine, and in the U.S. Pharmacopoeia from 1851 to 1942.

It was removed from the USP not because its medical uses were disproven, but because of the 1937 Marihuana Tax Act — a law written against the medical-cannabis tradition in favor of the pharmaceutical industry of the time. From 1942 to roughly the 1990s, cannabis was effectively outside medicine in the United States.

What's happening now is a return, not an invention. The difference is that patients in 2026 have tools that didn't exist in 1851 — standardized cannabinoid content on labels, third-party lab testing, published pharmacokinetic research, and the ability to look up interactions against every prescription they take. The plant isn't new. The infrastructure around it is.

06Before your first dispensary visit

If you only remember four things from this pillar: (1) cannabis works through a receptor system your body already uses; (2) THC is intoxicating, CBD is not, and they behave differently; (3) individual variation in dosing is real — start low; (4) everything else is tuning.

The next pillar in the sequence is Read the Label. Once you understand what cannabinoids do, the label stops being a wall of numbers and becomes a recipe you can read.