I was reviewing two certificates of analysis last fall — both flower products available at North Dakota dispensaries. The first tested at 28.3% total THC. The second came in at 19.1%. A patient I correspond with had tried both and reported, without knowing the numbers, that the 19% product provided more consistent relief for her chronic pain and fewer side effects. She asked me to explain why. I told her I'd need about eight hundred words, and she'd need to stop thinking of THC percentage as a quality score.

The 28% product's COA showed a terpene profile that was, to be charitable, sparse. Myrcene at 0.4%, trace amounts of limonene, and essentially nothing else worth reporting. The 19% product listed myrcene at 1.1%, beta-caryophyllene at 0.8%, linalool at 0.3%, and four additional terpenes above the limit of quantification. The cannabinoid profile was also more complex — measurable CBD, CBG, and CBN alongside the THC.

This is not an unusual comparison. It is, in fact, the norm. And it illustrates a problem I have watched the cannabis industry enthusiastically refuse to solve: the marketing of THC percentage as the primary indicator of product quality.

What the Number Actually Measures

Total THC percentage tells you the maximum amount of delta-9-tetrahydrocannabinol available in a given weight of product, typically calculated as THCa × 0.877 + THC. That conversion factor accounts for the loss of a carboxyl group during decarboxylation — the heat-driven process that converts the acid form into the psychoactive compound.

That is what it measures. It does not measure how the product will make you feel. It does not predict therapeutic efficacy. It does not account for the dozens of other compounds present in the plant that modify, enhance, or temper THC's effects. Choosing cannabis by THC percentage is — and I will stand by this analogy until someone offers a better one — like choosing wine by alcohol content.

Why Higher Doesn't Mean Better

A 2020 study from the University of Colorado Boulder (Bidwell et al., published in JAMA Psychiatry) examined blood THC levels and self-reported intoxication among participants using flower products of varying potency. The finding that matters here: participants using 24% THC flower did not report significantly greater intoxication than those using 16% flower, despite measurably higher blood concentrations. The authors suggested that other plant compounds, individual tolerance, and consumption behavior may matter as much as — or more than — raw potency.

This aligns with what analytical chemists have understood about complex botanical preparations for decades. A single-compound assay tells you one thing about a multi-compound matrix. It is necessary information. It is not sufficient information.

What to Look at Instead

If you have access to a certificate of analysis — and you should always ask for one — here is what I recommend examining beyond the THC line:

Terpene profile. Terpenes are the aromatic compounds responsible for differences in smell, flavor, and, increasingly, reported therapeutic effects between cultivars. A 2011 review by Ethan Russo (published in the British Journal of Pharmacology) proposed that terpenes like myrcene, limonene, and beta-caryophyllene modulate cannabinoid activity in clinically relevant ways. The evidence is still developing, but the framework is sound: the whole profile matters.

Minor cannabinoids. CBD, CBG, CBN, and CBC appear in varying concentrations and may influence the overall experience. A product with 18% THC and 2% CBD will likely produce a different effect than one with 18% THC and no measurable CBD.

Consistency across batches. If a product's THC swings from 22% to 29% between batches but its terpene profile shifts entirely, you are not buying the same product twice regardless of what the label says.

What's absent. A clean pesticide screen, acceptable residual solvent levels, and no microbial contamination are not selling points. They are minimums. But they appear on the COA, and they matter more than the THC number you're fixating on.

The Market Incentive Problem

I understand why dispensaries emphasize THC percentage. Patients ask for it. Patients have been trained — by an industry that found a simple number easier to market than a complex profile — to equate high THC with high value. Cultivators, in turn, breed and grow for maximum THC, sometimes at the expense of terpene diversity and minor cannabinoid content.

This is not a conspiracy. It is a market responding to a metric that is easy to measure, easy to advertise, and fundamentally incomplete. Changing it requires patients to ask different questions, and dispensaries to be prepared with better answers.

What You Can Do

Next time you visit a dispensary, ask to see the full certificate of analysis. Look at the terpene profile. Ask what minor cannabinoids are present. If the staff cannot answer those questions, that tells you something — not about their competence, necessarily, but about what the industry has decided patients need to know.

You deserve more than a number. You deserve a profile.