Open a jar of properly fresh cannabis and sometimes the smell arrives before the flower is even close to your nose. Pungent, gassy, sharp and powerful enough to fill a room.
People call it loud, gas or skunk, and for years that smell was commonly attributed to terpenes, particularly myrcene.
That explanation is incomplete.
Terpenes are responsible for many of the citrus, pine, floral and earthy aromas found in cannabis, but the characteristic skunky pungency comes from a different family of molecules: volatile sulfur compounds (VSCs). These compounds can be present at extremely low concentrations while still having an enormous impact on what your nose detects.
That also helps explain why a jar can smell incredibly loud when first opened and noticeably quieter a couple of weeks later.
Terpenes Don't Explain Skunk
Cannabis contains more than 200 known aroma compounds. Terpenes and terpenoids make up the largest group and account for many of the familiar aromas associated with different cultivars.
For example:
- Limonene: citrus
- Pinene: pine and fresh notes
- Linalool: floral and lavender
- Caryophyllene: pepper and spice
- Myrcene: musky and earthy
Myrcene was often associated with cannabis's skunky character because of its musky profile.
The problem is that terpene concentrations don't consistently explain how pungent different flowers smell. Cultivars with similar terpene profiles can have dramatically different levels of skunky aroma.
Something else was responsible.
The Sulfur Compounds Behind the Smell
A 2021 study published in ACS Omega used highly sensitive gas chromatography with a sulfur-specific detector to investigate cannabis aroma.
Researchers identified a previously undocumented group of prenylated volatile sulfur compounds, commonly abbreviated as VSCs.
One of the most significant was 3-methyl-2-butene-1-thiol, also known as prenylthiol.
The cultivars rated as particularly pungent contained higher concentrations of this compound, while some cultivars with little skunky character had none detected.
Why the Comparison to Skunks Is Literal
Skunk spray contains thiols, which are sulfur-containing compounds.
The sulfur compounds identified in cannabis belong to the same broad chemical family. That's why the similarity between cannabis and actual skunk odour isn't simply a metaphor—it has a chemical basis.
The Beer Connection
Prenylthiol is also associated with "skunked" beer.
When beer in a clear bottle is exposed to ultraviolet light, compounds derived from hops can break down and produce the familiar skunk-like odour.
Cannabis and hops are also closely related botanically, making the chemical overlap particularly interesting.
The Garlic Connection
Some of these cannabis sulfur compounds are structurally similar to sulfur compounds found in garlic.
That helps explain why certain cannabis cultivars can produce savoury, garlic-like or onion-like aromas that don't show up clearly on conventional terpene reports.
Why Your Lab Report Doesn't Show the Skunk
This is one of the most practical implications for cannabis consumers.
Standard cannabis testing generally focuses on cannabinoids and, when available, a selection of common terpenes.
Volatile sulfur compounds aren't normally included in those panels. They occur at extremely low concentrations and require specialised equipment and analytical methods to detect.
The human nose, however, is extraordinarily sensitive to many sulfur compounds.
That's why a terpene report can accurately describe the citrus, pine and pepper notes in a flower while completely missing the characteristic smell that makes the jar seem "loud."
Why "Loud" Cannabis Smell Fades So Quickly
The research also helps explain something many cannabis consumers have experienced.
VSC concentrations can rise sharply toward the end of flowering, peak during curing and then decline substantially after roughly ten days of storage.
That means:
- A freshly opened jar can smell dramatically stronger than the same batch a few weeks later.
- The loud, gassy character can fade before potency changes noticeably.
- Two batches of the same strain can smell different depending on how recently they were packaged.
- Terpenes may remain after some of the strongest sulfur aromas have faded.
As the flower ages, the balance between aroma compounds changes. The sharp skunky character can disappear first, leaving more of the citrus, pine, earthy or floral notes behind.
What Does That Mean for Cannabis Buyers?
Pungency can be a useful freshness clue, but it isn't a perfect quality test.
A very loud jar was likely packaged relatively recently, assuming the cultivar naturally produces substantial VSCs.
A quiet jar, however, isn't automatically stale. Some cultivars simply produce fewer of these compounds in the first place.
Use additional checks, such as those in our guide on how to tell if flower was cured properly, before deciding whether older-smelling flower is actually poorly stored or cured.
Cannabis Aroma Families at a Glance
| What You Smell | Main Compound Class | Typical Lab Report? | Fades Quickly? |
|---|---|---|---|
| Skunk, gas, "loud" | Volatile sulfur compounds | No | Yes |
| Garlic, onion, savoury | Volatile sulfur compounds | No | Yes |
| Citrus | Limonene / terpenes | Sometimes | Gradually |
| Pine, fresh | Pinene / terpenes | Sometimes | Gradually |
| Pepper, spice | Caryophyllene / terpenes | Sometimes | Gradually |
| Floral, lavender | Linalool / terpenes | Sometimes | Gradually |
| Earthy, musky | Myrcene / terpenes | Sometimes | Gradually |
| Hay, grass | Chlorophyll / poor cure | No | Doesn't improve |
The important distinction is that not every cannabis smell comes from terpenes.
Genetics Decide Whether the Skunk Is There
Not every cannabis cultivar produces the same amount of volatile sulfur compounds.
The research found significant variation between cultivars. Some lines contained relatively high VSC concentrations, while others had none detectable.
That means the strain name alone can't tell you how skunky a particular batch will smell.
Different phenotypes of the same cross can vary, and growing conditions can also influence the compounds a plant develops. Our guide on why the same strain is different everywhere goes deeper into this variation.
How to Preserve Loud Cannabis Aroma
If you specifically value strong gassy or skunky aroma, storage matters.
Keep Flower in Airtight Glass
Less headspace means less room for volatile compounds to escape each time the container is opened.
Keep It Cool and Dark
Heat accelerates the loss of volatile compounds. Keep cannabis away from radiators, direct sunlight, windows and other warm locations.
Open the Jar Less Often
Every time you open a container, you exchange the air inside with the surrounding environment.
If you're storing a larger amount, consider keeping a smaller working jar separate from a sealed reserve.
Maintain Appropriate Humidity
A two-way 62% humidity pack can help prevent flower from drying out.
This can be particularly relevant during an Ottawa winter, when heated indoor air can become extremely dry. See our cannabis winter storage guide for more information.
The Odour Side of Loud Cannabis
The same compounds that make cannabis smell extremely pungent can also make the odour noticeable in shared spaces.
Sulfur compounds can be detected by the human nose at very low concentrations, which helps explain why a particularly loud jar can quickly become noticeable in an apartment.
If you live in a multi-unit building, airtight storage is one of the simplest ways to reduce unnecessary odour escaping from stored flower.
What Skunk Smell Doesn't Tell You
A loud smell can tell you something about aroma, genetics and potentially freshness, but it doesn't tell you how potent the flower is.
A very pungent flower isn't necessarily higher in THC, and a relatively quiet flower isn't necessarily weak.
Likewise, there isn't evidence in the source material that these sulfur compounds determine how cannabis feels. Claims connecting skunky aroma directly to a particular effect should therefore be treated cautiously.
Uper Weed lists aroma and batch information where available across its flower and AAAA weed categories. Weed delivery in Ottawa can also make it easier to purchase smaller amounts more frequently rather than storing a large quantity until its aroma fades.
Frequently Asked Questions
A family of volatile sulfur compounds, including 3-methyl-2-butene-1-thiol (prenylthiol), contributes to cannabis's characteristic skunky aroma. These compounds belong to the same broad chemical family as the sulfur-containing compounds responsible for skunk spray.
Myrcene contributes musky and earthy cannabis aromas, but it does not fully explain the characteristic skunky pungency. Research has identified volatile sulfur compounds as important contributors to that smell.
The volatile sulfur compounds responsible for much of the loud skunky character can decline substantially during storage. They can fade faster than many terpenes, leaving the flower with a quieter citrus, pine or earthy aroma.
Standard cannabis testing commonly focuses on cannabinoids and selected terpenes. Volatile sulfur compounds occur at very low concentrations and generally require specialised analytical equipment, so they are not typically included in standard terpene reports.
No. Skunky aroma is associated with volatile sulfur compounds, genetics and freshness rather than directly indicating cannabinoid potency. A very pungent flower can have moderate THC levels, while a quieter flower can be potent.
Some cannabis sulfur compounds are structurally similar to sulfur compounds found in garlic. Cultivars with higher concentrations can therefore produce savoury, garlic-like or onion-like aromas that aren't explained by their terpene profile alone.
The Short Version
The characteristic skunk smell in cannabis isn't simply a terpene effect. Volatile sulfur compounds are responsible for much of the loud, gassy and skunky character, and they can be detected by the human nose at concentrations too low for typical cannabis lab reports.
These compounds can peak during curing and decline substantially during storage, which is why a freshly packaged flower can smell dramatically louder than the same batch a few weeks later.
A loud jar can be a useful freshness clue, but smell alone doesn't tell you potency or effects. If strong aroma is important to you, buy quantities you'll use relatively quickly and keep the flower sealed, cool, dark and properly stored.
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