Dried 18 percent: where this range overlaps with the declaration of 20 percent

• How many pieces of 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 action. 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 declared percentage on the flower label mean?

The percentage on the package is a declaration by the manufacturer, not a measurement result of that specific batch. The declaration carries a tolerance of ten percent in both directions, so the eighteen describes material from 16.2 to 19.8 percent. Some registered positions print these limits directly, while others provide only the nominal value. Nothing in this number indicates the strength of action.

The number refers to delta-9-tetrahydrocannabinol in its neutral form. In raw flower, the acidic form predominates, which the laboratory converts to this form, and the difference between the declaration and the measurement, as well as the calculation from the acidic form, is developed on the page dedicated to the twenty percent declaration.

Tolerance is a record of what is allowed, not a forecast of what has been measured. A position with a 20 percent declaration may be described in the composition with a statement about a content of no less than 18 and no more than 22 percent, and in pharmacy listings, it often stands with just the twenty. The reader then sees one number where the document presents a range.

Finally, a distinction that is easy to overlook. Cannabis flower sold over the counter in the cannabis flower category has a tetrahydrocannabinol content below the legal threshold and is not the same product as the raw material from the pharmacy. This page describes only the latter and is not a packaging list; the state of circulation is maintained by the list of available strains.

Why do the ranges for 18 and 20 percent overlap?

Because tolerance is calculated from the nominal value, not from the boundary of the neighboring declaration. The eighteen stretches from 16.2 to 19.8 percent, while the twenty ranges from 18.0 to 22.0. The segment from 18.0 to 19.8 belongs to both, so one measured value fits into two different labels.

The calculation involves four multiplications. The lower limit of the eighteen is 18 times 0.9, which is 16.2 percent, and the upper limit is 18 times 1.1, which is 19.8 percent. For the twenty, it comes out to 20 times 0.9, which is 18.0 percent, and 20 times 1.1, which is 22.0 percent. The common part starts where the lower limit of the stronger declaration meets the upper limit of the weaker one, and has a width of 1.8 percentage points.

Practically, this means that a batch described as weaker and a batch described as stronger can show the same number on the label, for example, 19.0 percent, while both remain compliant with their label. Neither is then described incorrectly. Going further: a batch from the eighteen measured at the upper end has 19.8 percent, and a batch from the twenty measured at the lower end has 18.0 percent, so the weaker label can sometimes be the stronger material.

What this calculation does not say: how often this happens. The range describes what is allowed, not the distribution of results from measurements in subsequent batches. Publicly available listings do not provide results for individual batches, so the percentage of batches landing in the common part remains unknown. However, the phenomenon is visible in the strain listing of this cluster: 26 out of 85 cultivars have a position with an eighteen percent declaration, and 16 of them are also listed in a stronger position.

How high does this common part reach on the declaration ladder?

Higher than would be inferred from the gap between the labels. Two declarations have a common part when the higher one is at most 1.222 times greater than the lower one. At this threshold, the eighteen overlaps with the twenty, touches the twenty-two exactly at one point, and the twenty-five overlaps with the thirty.

The threshold is taken directly from the definition of tolerance. The upper limit of the weaker declaration is 1.1 times its nominal value, and the lower limit of the stronger is 0.9 times its value, so the ranges have a common point as long as the ratio of both declarations does not exceed eleven ninths, or about 1.222.

This same rule explains why the common part does not disappear as the gap increases. The width of the range is two tenths of the declaration, so it grows along with it: 3.6 percentage points for the eighteen compared to 6.0 points for the thirty. Therefore, the twenty-five and thirty, although separated by five points of declaration, have a common segment from 27.0 to 27.5 percent, while the twenty-two and twenty-seven are separated by 0.1 points.

The eighteen has a special place here. Its upper limit, 19.8 percent, is also the lower limit of the twenty-two, because 22 is exactly eleven ninths of eighteen. These two declarations do not overlap, but touch at one point: the single value of 19.8 percent fits into both. Below are the limits of six declarations found in Polish registered positions.

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

This is determined by the attending physician, as this raw material is dispensed from the pharmacy only by prescription in the Rpw category. The matching process is gradual, starting from small doses towards one that produces an effect, and the declared percentage is just one of the parameters of this process, alongside the route of administration and frequency.

The matching itself is called titration and is developed separately on the page about the twenty-two percent declaration, along with the question of the variable tolerance of the patient over time. Here, one note arises from the calculation above: since the ranges of neighboring declarations have a common part, transitioning from the eighteen percent position to the twenty percent position does not necessarily mean a material stronger by two points, and sometimes it does not mean a stronger material at all.

The second reason why the label does not directly translate to the dose lies outside the raw material itself. The percentage describes the mass fraction in the flower, not how much substance will enter the body, as this is determined by the route of administration and the efficiency of the device. Two people using the same batch receive different amounts.

Therefore, the page with numbers does not replace a conversation in the office. The listing of limits shows what is allowed for the manufacturer, and nothing more: it does not say how much substance reaches the patient or what dose is appropriate for them. This remains the decision of the attending physician, made with the entire list of medications taken in mind.

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

No. The course over time is determined by the route of administration, not the number on the package. A higher declaration only indicates that the same mass of flower carries more active substance, so it is arithmetic of content, not a description of when the effect appears and how long it lasts.

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 fades 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. Hence the most common mistake with oral administration: someone 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 a pair of declarations from this page, the difference is smaller than it appears on the label. If a batch described as eighteen percent measures 19.0 percent, and a batch described as twenty percent measures the same, then both carry an identical amount of substance in the same mass of raw material, and nothing in their course can differ due to the label. The writing changes by two points, the material does not change at all.

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

It is known that higher concentrations are associated with worse outcomes in non-medical use, mainly on the side of psychosis and addiction. However, it is not known whether they provide more effective treatment: there are few medical works, their results vary in both directions, and the certainty of evidence has been rated as very low by the authors of the reviews.

The evidence material is asymmetrical. The largest review gathered 99 studies with a total of 221,097 participants, of which randomization was conducted in 42 percent. In studies that did not assess therapeutic use, high concentrations were associated with psychosis or schizophrenia in seventy percent of the works, and with cannabis addiction in seventy-five. Moderate or high risk of systematic error burdened over 95 percent of the included positions (PMID:40854216).

On the therapeutic side, the same review shows divergence, not a result. For anxiety, benefits were reported in 47 percent of studies, for depression 48, but the same sets of works also brought opposing signals, respectively in 24 and 30 percent. An older review, 20 observational studies selected from 4,171 screened articles, linked greater potency with an increased risk of psychosis and addiction, while for depression and anxiety, it deemed the evidence inconsistent, lacking a unified measure of exposure (PMID:35901795).

A newer review, based on 42 works selected from 4,545 records, divided potency into categories corresponding to the market, and rated the overall certainty of evidence as very low (PMID:40134269); the same categories are developed on the page about the twenty-five percent declaration. The fourth position is a meta-analysis showing that the raw material studied in earlier years was weaker than that in today’s circulation (PMID:33160291); this thread is addressed on the page about the thirty.

For this page, one limitation is important, common to all four works: none studies a single declaration. The categories used in these reviews have ten percentage points or more, and their boundaries cut through the ranges of labels across. The eighteen reaches up to 19.8 percent, which means it goes beyond the category from 10 to 19; the twenty, from 18.0 to 22.0 percent, lies in this category at the lower end, and at the upper end already in the next one. Thus, the separation of eighteen from twenty lies below the resolution of the evidence that exists.

What adverse effects are associated with higher potency raw material?

The same as with lower potency flower, except that reviews link higher concentrations with more frequent occurrences of psychosis and addiction in non-medical use. For the difference between the eighteen and twenty percent declarations, there are no separate data, as reports are not divided that finely.

Reports of adverse effects are collected for medicinal products with a batch number, not for the strain name, 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 numerical frequencies for these symptoms, as public listings for cannabis flower in Poland do not separate them by individual products.

The potency of the raw material adds only as much to this list as is visible in observational research reviews: more frequent reports of psychosis and cannabis addiction with higher concentration products, with the caveat that these are studies without randomization and without a unified measure of exposure. The adverse symptoms, along with what is known about their frequency, are developed on the page about the twenty-seven percent declaration.

Frequently asked questions

Can flower with an 18 percent label be stronger than flower with a 20 percent label?

Yes, and this results from the arithmetic of tolerance itself. The upper limit of the eighteen percent declaration is 19.8 percent, and the lower limit of the twenty percent declaration is 18.0 percent, so a batch from the former may contain more substance than a batch from the latter, both in accordance with the label.

Does a higher declared percentage mean stronger or better therapeutic action?

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

What is the range for the 18 percent declaration?

From 16.2 to 19.8 percent. The lower limit is 18 multiplied by 0.9, the upper limit is 18 multiplied by 1.1, which is a tolerance of ten percent of the nominal value in both directions. The entire range has a width of 3.6 percentage points.

Does the range mean that the measurement usually lies at its end?

No. The limits indicate what is allowed to be marketed under a given label, not how the results of measurements from subsequent batches are distributed. Public listings do not provide these results, so the frequency of hitting the common segment with the neighboring declaration remains unknown.

Does switching from the 18 percent position to the 20 percent position mean a stronger material?

Not necessarily. The ranges of both declarations have a common segment from 18.0 to 19.8 percent, so a two-point difference on the label does not have to correspond to any difference in content. Whether such a switch makes sense is determined by the attending physician, not the calculation of tolerance.

Where to check which positions with an 18 percent declaration are currently available?

In the list of available medical marijuana strains, which is updated separately and shows the state of circulation. This page is not a packaging list: it explains what the number on the label means, not which packages are currently in pharmacies.

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 decision of the attending physician. Editorial text: editorial team of ubucha.pl.