Declared 27 percent and the harm side: what research reviews link to higher potency
Dried flower with a declaration of 27 percent: what this number is, what systematic reviews associate with higher potency of the raw material, and why their results describe correlation rather than causation.
What does the declared 27 percent on the dried flower label mean?
It means the sum of THC, that is, the content of tetrahydrocannabinol along with its acid form converted to the active form. In freshly dried flowers, almost the entire load is still in acid form, so the number on the label describes the potential of the raw material after heating, not the portion that the patient absorbs during a single treatment.
The distinction between acid and active form is not a laboratory detail. Tetrahydrocannabinolic acid weighs more than the molecule that forms from it after the removal of carbon dioxide, so when converting, it is multiplied by a factor of 0.877. The monograph Cannabis flos in the European Pharmacopoeia describes the sum of THC, not just the neutral form, and this is how the declaration on the packaging of pharmaceutical raw material is read. Heating partially converts the acid to the active form, and part of the load is lost with vapor and residue, so the 27 from the label is not the amount that enters the bloodstream.
The declaration has an allowable deviation, so one number actually describes a range, not a point. Separately, the question stands as to how much of this declaration is confirmed by the measurement of a specific batch, as the study is conducted on a sample, not on the entire package. The overlap of neighboring potency ranges is elaborated on the page about eighteen procentach, and the distance between the declaration and the measurement is discussed on the page about twenty procentach. This page is not a product catalog: the assortment along with availability leads to a compilation of currently available medical marijuana strains..
How is the potency of dried flower selected for a specific patient?
This is determined by the attending physician, not the number on the package. The practice described in the literature involves starting with small amounts and gradually reaching the dose at which symptoms subside, while side effects remain manageable; the potency of the raw material is one of the variables in this calculation.
Higher potency changes not so much the goal as the jump between successive steps. The same volume of material carries more active substance at 27 percent than at twelve, so a single inhalation corresponds to a larger dose, and the margin of error becomes narrower. A person using the raw material for a long time usually tolerates stronger material better than a beginner, as tolerance builds with exposure. However, this same tolerance can lead to seeking increasingly stronger dried flower, and this is an area where reviews see a connection with cannabis addiction.
This page does not provide portion calculations because dried flower is a pharmaceutical raw material dispensed by a doctor's prescription in category Rpw, and the method of administration is determined by the attending physician. The mechanics of arriving at a portion are elaborated on the page about twenty-two procentach. Here, one distinction is sufficient: potency describes the raw material, while dose describes the treatment, and one cannot be converted to the other without knowing the route of administration and previous exposure.
Does the declared 27 percent change the onset and duration of action?
No. The declared potency determines how much substance is delivered by a single portion of material, not the rate at which the body absorbs and eliminates it. The onset and duration of the episode depend on the route of administration, so comparing potencies makes sense only when the route of administration is the same.
The route of administration determines the course more than the variety 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 lasts for 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 can last six, sometimes eight hours. Hence the most common mistake with oral administration: anyone who thinks nothing is happening after thirty minutes and takes another dose will receive both doses at once. The above ranges describe the route of administration, not this variety; pharmacokinetic studies for a single cultivar have not been published.
With stronger raw material, the slope of the same curve changes, not its shape. The same inhalation delivers more substance, so the peak occurs higher, not earlier, and it is this peak that determines whether the episode will be perceived as too intense. In oral administration, the difference is more serious, as the mistake described above costs more the stronger the material that went into the preparation. Thus, the declared percentage does not shorten the wait or lengthen the episode; it only shifts the height of the peak.
What is known about the relationship between the potency of the raw material and the effect, and what is not known?
Mainly, harm is known. The evidence regarding potency itself primarily describes psychosis and cannabis addiction and comes mostly from observational studies, meaning it shows correlation, not causation. Almost nothing is known about the relationship between the declared percentage and treatment efficacy.
A systematic review covering only observational studies involving humans (Petrilli et al., The Lancet Psychiatry, 2022, PMID:35901795) qualified twenty works from 4171 screened articles: eight concerned psychosis, eight anxiety, seven depression, and six cannabis addiction. Stronger products were associated with an increased risk of psychosis and addiction compared to weaker products, while for depression and anxiety, the evidence was inconsistent. The authors noted a lack of standardized exposure measurement, meaning that each of these twenty works measured potency in its own way.
A newer systematic review of observational and experimental studies (Lake et al., The American Journal of Psychiatry, 2025, PMID:40134269) selected 42 works from 4545 screened records and categorized the market by potency; the range from twenty to thirty percent also includes 27. The signal for problematic cannabis use leaned towards higher potency, while other areas were less consistent, though they tilted towards worse outcomes. Studies on therapeutic use were few and yielded mixed results, and the overall certainty of evidence was assessed by the authors as very low. The categorization itself is discussed on the page about twenty-five procentach.
The basis for comparison is movable: concentrations have increased over the years studied, as shown by the meta-analysis of subsequent years (Freeman et al., Addiction, 2021, PMID:33160291), so older works describe a raw material weaker than today's. The effects of this shift are elaborated on the page about thirty procentach.
What adverse effects are associated with higher potency raw material?
The same as with weaker raw material, only more frequent with comparable amounts of material. Two phenomena are separately described directly with higher potency: psychosis or schizophrenia and cannabis addiction. Both come from observational studies and both speak of correlation, not established causation.
Reports of adverse effects are collected for medicinal products with a batch number, not for the strain name, so the following pertains to hemp dried flower as a group of raw materials. The most frequently reported symptoms are dry mouth, red eyes, and increased heart rate. Dizziness upon rapid standing, daytime drowsiness, and temporary worsening of short-term memory are less frequently described, 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 the frequency of these symptoms numerically, as public compilations for hemp dried flower in Poland do not separate them by individual products.
The numbers for potency come from a systematic review of 99 studies involving 221,097 participants, in which 42 percent of the studies were randomized (Rittiphairoj et al., Annals of Internal Medicine, 2025, PMID:40854216). Among the studies that did not assess therapeutic use, products with high concentrations were negatively associated with psychosis or schizophrenia in 70 percent of the studies and with cannabis dependence in 75 percent; for anxiety and depression, the rates were 53 and 41, and these were most evident in healthy individuals. Over 95 percent of the included studies had moderate to high risk of systematic error.
In the branch assessing therapeutic use, the picture was different: nearly half of the studies found benefits for anxiety (47 percent) and for depression (48 percent), while some of them simultaneously described adverse associations (24 and 30 percent). Thus, both branches tell a different story.
The percentage of studies reporting a relationship is not the risk for an individual nor a measure of the strength of that relationship. The observational study compares groups that differ not only in the potency of the raw material but also in age, frequency of use, and the reason for using cannabis, so the reverse direction of the relationship remains open: a more severe course of the disorder may lead to stronger material, not the other way around.
Frequently Asked Questions
Does dried flower with a declaration of 27 percent work stronger than dried flower with a lower declaration?
With the same amount of material, it contains more active substance, which is not the same as stronger therapeutic action. Comparisons of two pharmaceutical dried flowers differing only in declared content have not been published, so the difference in therapeutic effect remains unknown.
Does a higher percentage on the label mean better therapeutic action?
It has not been shown that a higher declared percentage on the label indicates stronger or better therapeutic effects. The evidence regarding the potency of the raw material pertains almost exclusively to adverse effects and non-medical use, not efficacy, and studies on therapeutic applications are few and yield mixed results. The authors of both of the latest reviews assessed the certainty of evidence as very low. There is also no study that compared two pharmaceutical dried flowers differing only in declared content.
Is 27 percent a lot?
In terms used in the literature, this number falls within the range of twenty to thirty percent, which is in the upper part of the range described for dried flower. Above that are kief, resin, and concentrates, which this page does not address.
Does the declared 27 percent equal the measured 27 percent?
No. The declaration has an allowable deviation, and the measurement is performed on a sample taken from a batch. Therefore, the label with one number describes a range, not a value read from a specific package.
Does raw material with higher potency produce different adverse effects?
The reported symptoms are the same, differing only in frequency for comparable amounts of material. The adverse effects associated with higher potency include psychosis or schizophrenia and cannabis dependence, described in observational studies as comorbidities.
Who decides on the potency of raw material in treatment?
The attending physician, on the prescription in the Rpw category. The informational page does not replace either the indication or the selection of the form and method of administration.
Where to check which strains of this potency are available?
In the compilation of currently available medical marijuana strains, maintained by the hub of this collection of pages. This page describes only the number from the label and the state of evidence, not the assortment.
The material is informational and does not replace medical advice. Editorial: ubocha.
