Thirty percent: the upper end of the scale that has shifted over time

• How much evidence. 4 works from 2021 to 2025, all listed in the table below along with the model.
• What has not been shown. It has not been shown that a higher declared percentage on the label means stronger or better therapeutic effects. The evidence material regarding the potency of the raw material concerns almost exclusively adverse effects and non-medical use, not effectiveness.
• What you won’t find here. Dosage recommendations or strain indications. The choice is made by the attending physician, and cannabis flower is a raw material dispensed only by prescription.
• How to read this. The result of a study on rodents or in cell culture does not directly transfer to a patient taking the flower, and the column with the model indicates what the work was actually about.

What exactly does the thirty percent declaration on the raw material label measure?

The declaration describes the share of tetrahydrocannabinol in the mass of dried flower, converted from the acidic form to the neutral form, and not the strength of the perceived effect. The manufacturer provides a nominal value, to which a tolerance of ten percent of the value is added, so thirty percent means material falling between twenty-seven and thirty-three percent.

In dried flower, tetrahydrocannabinol mainly exists in the acidic form, which does not bind to the receptors of the endocannabinoid system. Only heating detaches a carbon dioxide molecule from it and converts it into an active form. The number on the package is therefore a converted value: it indicates how much active substance can be obtained from the raw material after heating, not how much is present in the raw material at the time of dispensing from the pharmacy. This principle applies to every declaration, but at the upper end of the scale, the conversion concerns a larger mass.

A tolerance of ten percent of the nominal value is not a small margin here. At thirty percent, the range reaches six percentage points, which is more than the gap between two adjacent positions from the middle of the range. The ranges of neighboring declarations overlap because of this, which we expand on the page about eighteen percent. Separately stands the question of how much the declaration from the series certificate corresponds to what the measurement shows, and this we dedicate a page to twenty percent. For the current assortment, we refer to the list of available strains, as this page describes the number, not the offer.

Why did thirty percent lie outside the scale two decades ago?

Because the scale has shifted over half a century. A meta-analysis published in the journal Addiction showed that the concentration of tetrahydrocannabinol in cannabis has increased from year to year, in dried material by about 0.29 percentage points annually, in samples collected from 1970 to 2017. The material that we now call strong was not available in circulation back then.

The work of Freeman and co-authors is not a single measurement, but a systematic review with a meta-analysis of concentration changes over time: it included twelve studies from seven countries and over sixty-six thousand samples of dried material. For resin, the rate was higher, at about 0.57 percentage points per year. The concentration of cannabidiol in the same material did not change in a way that could be demonstrated, so it was not the content of everything that increased, but just one substance (PMID:33160291).

For the page about thirty percent, this result has direct implications. The upper end of the offer is not standing still: the number that today indicates the strongest available material had no equivalent in the raw material two decades ago. The increase measured in tenths of a point looks modest on a yearly scale and gives several points on a generational scale, and it is precisely on this scale that literature on cannabis is read today.

What does the shifting of the scale do to the results of older studies?

It underestimates exposure. A study conducted on material from years past describes something weaker than what is available today in pharmacies, so directly transferring its results to today’s products leads the reader to think of a smaller amount of active substance than is actually at play with the same mass of dried material.

This consequence is inconvenient for the entire literature on cannabis, as it concerns not one study, but entire generations. The review by Petrilli and co-authors from The Lancet Psychiatry included only observational studies, and its authors noted the lack of a uniform measure of exposure (PMID:35901795). Without such a measure, it is impossible to say how much active substance participants from a decade ago were taking compared to participants studied today, and without that, comparing risks between generations remains an approximation.

At thirty percent, the problem is the sharpest, as it is the upper end of today’s pharmacy offer. The higher up the scale, the fewer older studies describing comparable material, and the fewer such studies, the more inference by analogy is required. This is even visible in the registration data collected for this compilation: out of eighty-five cultivars, sixty-nine have a declared content, the highest nominal declaration read from them is twenty-nine percent, and sixteen positions do not have a declared tolerance at all. There is still no declaration of thirty percent in this collection, although such positions have already appeared in pharmacies.

Does the word “strong” have a fixed reference point?

No, it does not. What today stands at the upper end of the offer lay outside the scale of available material two decades ago, and what was then called strong is now in the middle of the range. The word thus describes a position in the market of a given year, not a property of the plant.

This is evident in how the literature has to deal with the division into categories. The authors of the review from The American Journal of Psychiatry built a division corresponding to the real market, from the lowest ranges to concentrates, and the very fact that such a division had to be constructed for one work speaks to the lack of a common reference system (PMID:40134269). We dedicate a separate page to the power categories drawn from the literature about twenty-five percent.

A moving reference point has very practical implications. The statement “I have already had strong flower” says nothing until it is known from which year that memory comes and what declaration stood behind it. For the same reason, comparing experiences between individuals treated in different years leads to dead ends, and the only place where the number returns to its place is a conversation with the attending physician about a specific registration position. The same attention applies to descriptions found online: a mention of strong flower without a given declaration and date carries no information that could be verified.

How is the potency of the raw material matched to the patient?

The attending physician decides, not the number on the package. The declared percentage describes the raw material, not the dose: the same content provides a different amount of active substance with a different mass of dried material and a different route of administration. Positions from the upper end of the scale are practically given to individuals with established tolerance.

Tolerance changes what the same content does to a specific person. In a patient who has been taking cannabis for a long time, the reaction to the same raw material may be weaker than in someone who is just starting, so two doses with identical declarations are not equivalent. The difference does not lie in the flower, but in the recipient, and the website has no way to assess it.

The method of reaching the dose, that is, titration, is described on the page about twenty-two percent and details should be sought there. Here remains the observation resulting from the topic of this page: since the scale has shifted over time, one’s own experience from years past is also not a good starting point. The choice of registration position belongs to the physician, who knows the diagnosis and the other medications being taken, and dispensing the raw material in the Rpw category still requires a prescription.

Does the declared percentage change the onset and duration of action?

No, it does not. The onset and length of the episode are determined by the route of administration, not the declared content. With a higher declaration, the same mass of dried material simply carries more active substance at the same time.

The route of administration determines the course more than the strain itself. After vaporization, the substance passes from the lungs to the blood almost immediately, so the first sensations appear after a few minutes, the intensity increases for another ten to thirty minutes, and the whole effect wears off within two to four hours. After ingestion, the raw material first passes through the intestine and liver, so the first sensations are awaited from half an hour to two hours, and the episode lasts six, sometimes eight hours. This is where the most common mistake in oral administration comes from: anyone who thinks nothing is happening after thirty minutes and adjusts the dose will receive both doses at once. The above ranges describe the route of administration, not the strain; pharmacokinetic studies for a single cultivar have not been published.

For material at the upper end of the scale, there is one practical difference. A mistake in oral administration costs more because it concerns a dose with a higher content, not because the episode proceeds differently over time. No one has measured the course of action separately for thirty percent raw material and separately for weaker material, so the ranges given above remain a description of the route of administration, not a description of this declaration.

What is known and what is not known about the relationship between raw material potency and effect?

It is known that higher potency is associated with more frequent problematic use of cannabis and a higher risk of psychosis. It is not known whether it translates into better therapeutic effects: the evidence material concerns almost exclusively adverse effects and non-medical use, and the certainty of the evidence has been assessed by the authors of the latest reviews as very low.

The four works on which this page stands discuss different things and differ in the study model, so the model stands with each of them.

The discrepancies between these works are information, not a flaw. The review from Annals of Internal Medicine found nearly half of the results favorable for anxiety and depression among studies on therapeutic use, but some of the same studies simultaneously noted unfavorable associations, and the risk of systematic error was assessed as moderate or high in over ninety-five percent of the material included in the review (PMID:40854216). The review from The American Journal of Psychiatry assessed the overall certainty of the evidence as very low, and the review from The Lancet Psychiatry relied solely on observational studies, in which exposure is inferred from what participants reported.

For a single declaration, including thirty percent, there is no separate result. The categories used in the literature encompass broad ranges, not specific registration positions, so these reviews cannot indicate how thirty percent raw material differs from twenty-seven percent raw material.

What adverse effects are associated with higher potency raw material?

The same as those described for cannabis flower in general, except that with a higher declaration, they are easier to experience with the same mass of raw material. There is no separate compilation of frequencies for thirty percent material because reports are collected for medicinal products with a serial number, not for declared potency.

Reports of adverse effects are collected for medicinal products with a serial number, not for strain names, so the following pertains to cannabis flower as a group of raw materials. The most common effects include dry mouth, red eyes, and increased heart rate. Dizziness upon rapid standing, daytime drowsiness, and temporary worsening of short-term memory are less frequently reported, as well as anxiety that increases with dosage. A separate issue is medications taken concurrently, especially sedatives and those affecting coagulation: their assessment requires knowledge of the entire list of preparations, not just the description of the plant. We do not provide frequencies of these symptoms numerically because public compilations for cannabis flower in Poland do not separate them by individual products.

As for the relationship with potency, the reviews collected above mention more frequent problematic use and a higher risk of psychosis with stronger products, but they do so based on observational studies and with the certainty of evidence assessed as very low. We dedicate a separate page to twenty-seven percent, here remains the observation that a higher declaration does not change the list of symptoms, it changes the mass of raw material at which they appear.

Frequently asked questions about the declared potency of flower

Does a higher declared percentage mean stronger therapeutic effects?

It has not been shown that a higher declared percentage on the label means stronger or better therapeutic effects. The evidence material regarding the potency of the raw material concerns almost exclusively adverse effects and non-medical use, not effectiveness, and studies on therapeutic use are few and yield mixed results. The authors of both the latest reviews assessed the certainty of the evidence as very low. There is also no study that compared two pharmacy flowers differing only in declared content.

Is thirty percent the highest potency of flower available in Polish pharmacies?

This is currently the upper end of the pharmacy offer. Previously, this end was lower, and nothing indicates that it will remain stationary, which is why we keep the current list of positions in one compilation of strains, not on this page.

Where does the range from 27 to 33 percent come from with a thirty percent declaration?

From the tolerance of ten percent of the nominal value, which is allowed for the manufacturer’s declaration. Thirty percent minus a tenth gives twenty-seven, and thirty percent plus a tenth gives thirty-three.

Do older studies on cannabis describe the same raw material as today’s?

No. A meta-analysis from the journal Addiction showed an increase in the concentration of tetrahydrocannabinol in successive years, so the material from older studies was on average weaker, and transferring those results to today’s products underestimates exposure (PMID:33160291).

Does high declared flower work longer?

No. The onset and duration of the episode are determined by the route of administration, not the declared content. After vaporization, sensations appear within a few minutes and wear off within a few hours; after oral administration, everything shifts and extends.

Who decides on the choice of raw material potency for the patient?

The attending physician. Cannabis flower is a pharmaceutical raw material dispensed by prescription in the Rpw category, and the choice of registration position requires knowledge of the diagnosis and other medications being taken, which the website cannot replace.

Cannabis flower is a pharmaceutical raw material dispensed by prescription in the Rpw category. The material is informational in nature and does not replace medical advice or the decisions of the attending physician. Editorial text: editorial team ubucha.pl.