Myrcene: twenty strains from the list, three studies on mice, zero on humans

What is myrcene and where does it occur outside of hemp?

Myrcene is a volatile monoterpene with the formula C10H16 and a molecular weight of 136.23, composed of an open carbon chain, without a ring. The public PubChem card lists it under number 31253 as beta-myrcene, and among natural sources outside of hemp, it mentions bay laurel oil, verbena, hops, and lemongrass, which are plants that no one associates with hemp.

In the pharmacy list of this cluster, myrcene is a leading terpene for twenty out of eighty-five cultivars, meaning for thirty-one positions out of one hundred forty-one. It is surpassed only by caryophyllene, indicated for thirty strains. This position comes from pharmacopoeial labels, not from editorial choice: we count what the manufacturer provided on the packaging, and nothing more.

Outside of pharmacies, the same compound works as a raw material in the fragrance industry. The HSDB record available through PubChem lists its use in fragrance compositions, flavoring, in insect repellent preparations, and as an additive to detergents, and primarily its role as an intermediate in the production of terpenic alcohols. The same record states that it is industrially obtained from the pyrolysis of beta-pinene., thus from another terpene present in hemp. This is significant for the further part of the text: the amount that a chemical plant worker encounters and the amount contained in a few milligrams of dried flower are two different exposures, and the literature on the pure substance describes the former.

How long does it take for myrcene to reach the body and how long does it stay there?

It is unknown, as no one has measured this separately for myrcene inhaled with dried flower. Public literature describes the action of the entire raw material according to the route of administration, not the fate of a single molecule from the profile, so a fair answer is this: the following time intervals belong to the route of administration, not to this terpene.

Two things can be quantified here, both related to the compound, not the patient. Pure beta-myrcene boils at atmospheric pressure around 166.8 degrees Celsius, which comes from the average of two measurements taken at 760 mm Hg. How much of this compound leaves the dried flower when heated and how much reaches the blood is not provided by any entry collected in this project. The distance between these questions is greater than it seems: the first concerns a vessel with a reagent, the second the ground plant material in the chamber of the device, where the compound sits in resin glands along with the rest of the profile.

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.

Does the boiling point of myrcene say anything about the vaporizer setting?

No. The boiling point describes the pure substance in a laboratory vessel, not the dried flower in the device's chamber, and it is not a setting for the equipment. For beta-myrcene, the public database holds four records from four institutions, two of which carry the pressure at which they were measured, and only those two can be compared.

The average of these two gives 166.8 degrees Celsius at 760 mm Hg. The remaining records state 167 degrees and a range of 166-167 degrees, but without information about pressure, so they did not enter the average. The institutions behind these four records are CAMEO Chemicals, HSDB, HMDB, and JECFA. Pressure is not a note for pedants here: in the same database humulene there is only one measurement taken at 3 mm Hg, which is almost in a vacuum, and it results in 99.5 degrees. Comparing such a number with a measurement under atmospheric pressure would be comparing two different magnitudes. Myrcene has no record under reduced pressure. therefore, its number can be compared with the rest of the table.

What this number does not say: at what temperature myrcene leaves the ground flower, how much remains after heating, and how much reaches the lungs. The dried flower is not a vessel with a pure reagent; the compound sits in it in glands along with the rest of the profile, so the boiling point of the pure substance is an upper reference point, not the moment of evaporation from the plant material. For this reason, we do not provide any device settings or methods of intake here: they do not arise from anything stated in the data of this project.

What have studies shown about the effects of myrcene?

Three studies, all on mice. This is the extent of the evidence base for myrcene in this project, and not one entry included humans. Two administered the compound via injection into the peritoneal cavity, the third as vapor inhaled by the animal, and the direction of the result changes with this difference.

The database is not a collection of three independent teams. Viana GS is associated with two of the three positions, the one from 1990 and the one from 2002, so the older material comes from one research line, not from repetitions at different centers. The 1990 study concerned pain responses and indicated an intermediate mechanism: the effect disappeared after administration of naloxone and yohimbine. The 2002 study measured animal mobility, sleep duration after pentobarbital, and behavior in the elevated plus maze, and its authors described the result as weakly anxiogenic.

The position from 2024 is the only one that mimics inhalation in humans and is the only one that separates the result by sex. The anxiolytic effect was observed in females, in males only with a single inhalation, and there was no enhancement of the effect of cannabidiol in either sex, unlike for linalool studied in the same setup. None of the twenty-two positions collected for eleven terpenes included humans, and two of them do not even concern mammals. Doses from injections were given in milligrams per kilogram of animal body weight, which is a measure that cannot be translated to what a human receives when inhaling dried flower.

What has not been demonstrated about mircene?

What is most often repeated about it has not been demonstrated. Popular strain descriptions associate it with drowsiness and support this with studies on mice that were given an injection into the peritoneal cavity, a route that the patient does not have. The evidence base of this project sets a clear boundary, and its statement reads literally as follows:

In humans, myrcene alone has not been shown to alleviate insomnia at doses typical for inhalation of dried flower. The direction of the effect in rodents depends on the route of administration and sex: intraperitoneal injection in 2002 described a slightly anxiogenic effect, while inhalation in 2024 showed an anxiolytic effect in females. These two results do not negate each other; they simply show that the conclusion depends on conditions that no popular strain database provides.

Three things in this sentence weigh more than they appear. First: the authors of the 2002 study described their result as weakly anxiogenic, which is in the opposite direction to what popular strain descriptions attribute to mircene. Second: the result from 2024 depends on the sex of the animal, and a conclusion dependent on sex cannot be recorded as a statement about the compound's effect on humans. Third: none of these studies measured how much mircene leaves the dried flower or how much reaches the blood, so the dose at which any of this would occur remains unknown.

This material also contains a negative result, which is also a result. The 2024 study checked whether mircene enhances the effect of cannabidiol administered concurrently, and no such enhancement was found in either sex, although the same setup found it for linalool. The statement about the interaction of terpenes, repeated in strain descriptions without reservations, was specifically tested for this pair and came out negative.

What adverse effects have been reported after mircene?

None, if the question concerns mircene as a separate substance. Safety monitoring is conducted by product batch number, not by the name of the compound from the profile, so a list of symptoms attributed specifically to this terpene in people using dried flower has not been created and there is nothing to compile it from. Below is what is known about the raw material.

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 situation is different for the pure compound. Industrial mircene is a reagent described in databases of hazardous substances, and concentrated volatile terpenes can irritate the respiratory tract and skin. However, this is an observation about liters of reagent in a facility, not about a few milligrams dispersed in dried flower alongside a dozen other compounds. Transferring this directly to inhaling dried flower would be the same mistake as transferring results from an injection in mice to a patient: the quantity, form, and route change, along with the meaning of the numbers.

Which strains from Polish pharmacies have mircene as the leading terpene?

Twenty names, and their compilation is in the table below this paragraph along with the manufacturer and the number of registered positions. The indication comes from the pharmacy list, not from the descriptive database, so it speaks to what the producer declared for a given position, not what someone measured in the flower.

The thirty-one registered positions held by this twenty are unevenly distributed. Cataract Kush has the most with four, Frosted Cherry Cookies and Blueberry each have three, while thirteen strains are listed in a single position. Among the producers, Canopy Growth frequently appears with six cultivars, followed by S-LAB with five and Tilray with four. There are ten entities in this group, with Medezin and CanPoland each having one. Five names from this twenty are supplied by more than one producer, while the remaining fifteen are listed under one. This is important when reading the label: the leading terpene is a declaration assigned to the registered position, so the same trade name from two producers can have two separate entries.

The composition of this list changes over time and this is not a flaw of the compilation, but a property of the market: licenses expire, supplies run out, and new positions come under a different registered name. The current state of availability leads to a summary of available strains, and products with hemp dried flower have been gathered in a separate category of the store.

How does the pharmacy list differ from the composition provided by profile databases?

The difference is that they answer different questions. The pharmacy list indicates the leading terpene and provides twenty strains for myrcene, while profile databases list it in the composition of sixty-seven. Merging both numbers into one would yield a value that none of these sources confirm, so we keep them separate.

Both lists overlap in nineteen names. Forty-eight cultivars contain myrcene in their composition, although the register did not indicate it as the leading one, while only White Widow X goes the other way: the pharmacy label lists myrcene for it, but there is no public profile for this strain at all. A separate case is GMO, where the register states myrcene, while profile databases attribute the largest share to farnezen. This appears to be a data error, but is simply a result of the fact that the label and descriptive database measure different things.

This gives rise to the rule that we do not assign a share when naming a terpene. We calculated this using our own data: in the BudCare database, myrcene appears in 110 positions out of 146, while the sum of declared shares of all terpenes in one position is 46, in another 118, with a median of 85. Five positions exceed one hundred, meaning they declare more in total than the total amount. Therefore, the denominator is unknown and different in each position, and a number without a denominator in a text about a drug appears to be a measurement, which it is not. The second database, MedWeed, does not provide shares at all: it lists myrcene for fourteen out of sixty-five positions and organizes terpenes by weight, placing it first in nine of those fourteen.

Frequently asked questions about myrcene

Does myrcene induce sleep?

This has not been demonstrated in humans. In a 2002 study, mice injected intraperitoneally slept longer after pentobarbital, but that is a result in rodents and via a route of administration that patients do not use. No position in this project's database measured sleep in humans after myrcene.

How many strains from Polish pharmacies have myrcene as the leading terpene?

Twenty out of eighty-five cultivars described in this cluster, corresponding to thirty-one positions out of one hundred forty-one in the register. Only caryophyllene has more, indicated for thirty strains. Profile databases count separately, listing myrcene in the composition of sixty-seven strains.

Does myrcene have anxiolytic effects?

It depends on the conditions, and this is not an evasion. After intraperitoneal injection in 2002, a slightly anxiogenic effect was described, while after inhalation in 2024, an anxiolytic effect was noted in female mice. The direction thus changes along with the route of administration and the sex of the animal, and there is no single statement about humans from this.

Why don't you provide how much myrcene is in the strain?

Because the denominator is unknown. In the BudCare database, myrcene appears in 110 entries out of 146, and the total declared shares of all terpenes there are sometimes 46, sometimes 118, with a median of 85. Five entries exceed a hundred, so the number next to the terpene name would appear to be a measurement, which it is not.

At what temperature does myrcene boil?

Approximately 166.8 degrees Celsius at atmospheric pressure, which is the average of two measurements taken at 760 mm Hg. Two further measurements in the same database were provided without pressure, so they were not included in the average. This number describes the pure substance and is not a vaporizer setting.

Has myrcene been studied in humans?

No. The evidence base for this project has three entries for myrcene, all conducted on mice: two with intraperitoneal administration, one with inhalation vapor. None of the other entries collected for the eleven terpenes in this cluster included humans.

Dried hemp is a pharmaceutical raw material dispensed by a doctor's prescription in the Rpw category. The material is informational in nature and does not replace the advice of a doctor or pharmacist.

The editorial text was prepared by redakcja ubucha.pl.