Dried flower label at twenty percent: total THC, acid form, and a ratio of 0.877

What exactly does twenty percent on the dried flower label mean?

It means that the producer declares twenty percent of total tetrahydrocannabinol in a gram of dried raw material, and the laboratory must confirm this value through measurement. The monograph allows for a ten percent difference between the measured and declared content, so under one number lies a range from eighteen to twenty-two percent, not a point.

The declaration includes total tetrahydrocannabinol, which is the sum of the neutral form and its acid counterpart converted to THC. The same notation applies to cannabidiol, as the monograph requires both values simultaneously. The measurement is performed by the laboratory using chromatographic methods on a sample taken from the batch, and the result refers to the mass of the dried raw material.

The number on the label is therefore a report of the composition measurement, not a promise of what the patient will feel. It describes one gram of the flower at the time of testing the batch. It says nothing about the dose, the method of administration, or the outcome of therapy, although in casual reading, it takes on all three roles at once.

This page is not a product list and does not mention any items from the offer. What is currently in circulation and with what declaration is shown to a compilation of currently available medical marijuana strains.. We also explain separately, why the ranges of neighboring declarations overlap.

How does tetrahydrocannabinol differ from its acid form?

They differ by one carboxyl group, and that is enough for them to be two separate compounds. In freshly harvested and dried flower, tetrahydrocannabinol primarily occurs as tetrahydrocannabinolic acid, abbreviated as THCA. Only the removal of this group, i.e., decarboxylation, converts the molecule into THC, which is discussed in the literature regarding the action of the raw material.

The plant does not produce the neutral form. An enzyme called tetrahydrocannabinolic acid synthase converts the common acid precursor into THCA, and it is this acid that accumulates in the glandular hairs of the flower. The neutral form is produced later, outside the plant's metabolism, in a reaction that does not require any enzyme but does require energy.

For reading the label, this has a straightforward and often overlooked consequence. If the laboratory provided only THC measured in the raw dried flower, the value would be significantly lower than what the producer declares, as most of the material is still in the acid form. The monograph resolves this by requiring both forms to be counted together, after converting the acid to its neutral counterpart. Therefore, the label describes the potential of the raw material, not the content of the active substance in the jar.

The result of the batch testing is sometimes presented in two columns: the neutral form separately, the acid separately. Those who read only the first one perceive a fraction of what the raw material actually carries. Those who sum both without conversion inflate the result by the mass that escapes as gas when heated and reaches no one.

Where does the conversion factor 0.877 come from?

From the ratio of the molecular masses of both forms. Tetrahydrocannabinol has the molecular formula C21H30O2, while its acid form is C22H30O4, meaning the same molecule enlarged by a carboxyl group. During decarboxylation, carbon dioxide is released from it, so from one gram of acid, less than 0.88 grams of THC remains, and the rest escapes as gas.

The calculation can be performed on paper. The masses from the table give a ratio of 314.47 divided by 358.48, which is 0.8772, rounded in regulations to 0.877. Checking from the other side yields the same result: 358.48 minus 44.01, which is the mass of carbon dioxide, gives exactly 314.47. The missing 12.28 percent of the mass is the gas that escapes when heated.

The same conversion factor works in two places at once. The pharmacopoeial designation counts the content of the neutral form together with its corresponding acid, correcting the result by the ratio of molecular weights. American cannabis regulations state this directly as a sum: the THC content increased by 0.877 of the THCA content. The molecular formulas of both compounds are provided by the public database PubChem, maintained by the National Center for Biotechnology Information.

Two things can easily be confused here. The ratio of 0.877 refers to molecular weights, not a measure of how efficiently the transformation occurs outside the laboratory. It indicates how much THC would be produced from the acid during complete transformation, not how much is produced in the patient's device or how much remains after six months in a jar. The label declaration is calculated using the first method, meaning it describes the upper limit, not the actual state at the moment of use.

Why does raw dried flower mainly contain the acidic form?

Because that is how it comes from the plant and nothing further processes it. The enzymes in hemp finish their work in the acidic form, and the transformation into THC occurs without their involvement: slowly during drying and storage, quickly when heated. Therefore, a freshly cut flower primarily carries THCA.

The transformation also occurs when no one initiates it. The acid breaks down over time, and heat and light accelerate this breakdown; with longer storage, some of the produced THC further oxidizes into cannabinol. Thus, measuring only the neutral form would yield different results on the day of packaging and six months later, even if the jar remained untouched.

The sum of both forms is resistant to this variability, which is why the label provides that number. However, it is important to know what this number does not include: it describes the potential of the raw material after complete transformation conducted under laboratory conditions. How much of this potential will be produced in the device and how much will reach the body is not disclosed by the declaration, as it is not its purpose.

Hence, there is another consequence for reading the label. The number describes the state from the day of testing the batch, not a permanent property of the strain: the same batch measured after a longer time will yield a different result, although the name on the package will remain unchanged. The expiration date is as important here as the percentage itself, and storage conditions affect both of these quantities simultaneously.

Can the number on the label indicate the dose for the patient?

No. The declaration describes the composition of one gram of raw material, not the amount the patient takes or the rate at which that amount reaches them. The decision on what raw material and in what form will be used is made by the attending physician, as dried flower is dispensed only by prescription in the Rpw category.

Percentage and amount are two different quantities, and confusing them is the most common mistake when reading the label. The declaration states what portion of the raw material's mass corresponds to total tetrahydrocannabinol. It does not say how much of that mass will be used or how much substance will enter the bloodstream. The same number with two different methods of administration indicates two different experiences.

Choosing the amount in small steps and how the patient's tolerance changes over time, is described at the neighboring shelf of declarations. Here, one note is sufficient: comparing declarations between manufacturers makes sense only when both were derived from the same method of calculation, meaning both are total tetrahydrocannabinol, not just the neutral form.

The declaration refers to dry mass, not to volume or appearance of the material. Two packages described by the same number may differ in fragmentation, moisture, and weight of a single flower, which changes how much raw material is actually measured in the pharmacy, even though the percentage on both labels remains the same.

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

No, it does not change. The declaration determines how much substance corresponds to a gram of raw material, not when the effect begins or how long it lasts; the route of administration determines the timing. The following description therefore pertains to routes of administration, not this or any other shelf of the declaration.

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.

For the label reader, the conclusion is that the percentage number and the timing of effects are two separate things that can easily be conflated. The declaration describes the composition of the material before administration, while the above intervals describe what happens afterward and what depends on the route, not the label.

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

What is mainly known is about the harms, not the benefits. Four reviews that can be referenced here primarily deal with non-medical use, and the studies on therapeutic applications are few and divergent. None of these reviews uses the label declaration as a measure of exposure.

The closest to the question of potency itself are Petrilli and colleagues (The Lancet Psychiatry, 2022, PMID:35901795). The study model is worth noting: it is a systematic review that only included observational studies conducted on humans. The filter allowed 20 entries out of 4171 reviewed articles; eight described psychosis, eight anxiety, seven depression, and six cannabis dependence. For the first two areas, the direction was consistent: using material with higher concentration was associated with more frequent psychosis and more frequent dependence than using weaker material. The picture diverged for depression and anxiety.

The authors added a caveat that weighs more for this page than the result itself: there is a lack of a standardized measure of exposure. Since studies do not measure potency in one way, the pharmacy declaration has no equivalent in this literature, and transferring conclusions directly to one percentage shelf is a guess, not a reading.

The same problem is evident in Lake’s and colleagues' work (The American Journal of Psychiatry, 2025, PMID:40134269). The authors reviewed 4545 records, leaving 42 positions and covering observational and experimental studies. The clearest signal concerned problematic cannabis use; apart from this one area, the results were weaker, leaning towards the worse side where the material was stronger. There were few studies on therapeutic use, and they reported different things, with the authors determining the overall certainty of the evidence as very low. We address the division of the material into strength ranges they used, in the higher declaration.

The fourth study concerns not so much the effect as the raw material itself. Freeman and colleagues (Addiction, 2021, PMID:33160291) compiled a meta-analysis of subsequent measurement years and showed that the concentration of tetrahydrocannabinol in cannabis has increased over the years, so older studies describe material weaker than what is currently on the market; this thread is developed in the highest declaration.

What adverse effects are associated with higher potency raw material?

There is no separate compilation for the twenty percent declaration. Evidence regarding the potency of raw material describes broad ranges at once and primarily discusses psychosis and problematic cannabis use, which are consequences of long-term non-medical use, not symptoms that the patient notes during therapy conducted by a physician.

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 from the reviews are not frequencies of symptoms, but percentages of studies in which a given association occurred at all. Rittiphairoj and colleagues (Annals of Internal Medicine, 2025, PMID:40854216) collected 99 studies involving 221,097 people, with randomization applied in 42 percent; this is a systematic review, not a single clinical trial. Where non-medical use was assessed, high tetrahydrocannabinol concentration material performed poorly in terms of psychosis or schizophrenia in 70 percent of studies, and in terms of cannabis dependence in 75 percent. For anxiety, this percentage was 53, for depression 41, and this mainly concerned healthy individuals.

In studies on therapeutic use, the picture only partially reverses: 47 percent noted benefits for anxiety, 48 for depression, while 24 and 30 percent of the same studies found concurrently unfavorable associations. The risk of systematic error was assessed as moderate or high in over 95 percent of the included studies, so none of these numbers can be read as a measure of risk for an individual patient. How these observations look at even higher declarations, opisujemy osobno.

Frequently Asked Questions

Does a higher declared percentage mean stronger therapeutic effects?

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.

What does the abbreviation THCA mean in the dried flower analysis?

THCA stands for tetrahydrocannabinolic acid, which is the form in which the plant actually stores tetrahydrocannabinol. It differs from THC by one carboxyl group, which it loses when heated. In the raw, dried flower, this is the majority of the content.

Why does the label provide total tetrahydrocannabinol instead of just THC?

Because both forms coexist in the raw material, and their ratio changes over time and under the influence of heat and light. The sum of both, after converting the acid with a factor of 0.877, is a stable quantity, while the neutral form would yield a different result with each measurement.

Where does the number 0.877 come from?

From the ratio of molecular weights: 314.47 for THC versus 358.48 for its acidic form. The difference is carbon dioxide with a mass of 44.01, which is released during decarboxylation. The ratio is 0.8772 and in this rounded form it is used in the calculation of total content.

Do two dried flowers with the same declaration have the same content?

Not necessarily. The allowable difference between the measured and declared value is ten percent, so two items described the same way may lie at opposite ends of the same range. Comparison makes sense only if both numbers were derived from the same method of calculation.

Does the content change during storage?

The ratio of both forms does change: the acid slowly loses its carboxyl group, and the resulting THC oxidizes over time to cannabinol. Heat and light accelerate this process. The declaration covering both forms at once is precisely to prevent such a passage of time from skewing the result.

Hemp dried flower is a pharmaceutical raw material dispensed by prescription in the Rpw category, and its use is determined by the attending physician. The material is for informational purposes and does not replace medical or pharmaceutical advice. Editorial text: ubocha.