Does Cannabis go out of date?
At CB1 Medical, we’re often asked: does cannabis go out of date? While cannabis doesn’t spoil like food, it can lose potency, flavour, and therapeutic value over time — and in some cases, even develop mould, which may pose health risks.
In this guide, we’ll cover how long cannabis typically stays fresh, signs of degradation, and how to store it properly to maintain its safety and effectiveness.
Contents
How long does Cannabis stay fresh?
When stored correctly, dried medical cannabis can remain potent and effective for six months to a year. After this point, cannabinoids like THC and CBD begin to break down, and the flower may lose its characteristic aroma and texture.
In a study published by the Journal of Pharmacy and Pharmacology, researchers found that THC content in dried cannabis decreased by:
- 16% after one year
- 26% after two years
- 34% after three years
- 41% after four years
This gradual loss of potency means that even well-cured cannabis will eventually become less effective — something especially important for patients using it to manage chronic conditions.
Can Cannabis expire?
Cannabis doesn’t have a formal expiry date, but it degrades over time — especially with exposure to air, light, heat, or moisture. This can lead to:
- Reduced effectiveness
- Harsher taste or texture
- Changes in smell
- Potential mould growth
While not harmful for most, degraded cannabis may offer less symptom relief. For immunocompromised patients or those with lung conditions, mouldy cannabis can pose health risks.
Signs that your Cannabis may be past its prime
- Smell: A stale, musty, or grassy smell may indicate degradation. Hay-like or damp odours could suggest mould.
- Appearance: Faded colour, loss of trichomes, or white/grey fuzzy spots can all be signs of age or contamination.
- Texture: Flower should be slightly sticky. Crumbly or damp textures indicate drying or moisture exposure.
How to check for mould on Cannabis
Mould may appear as white or grey fuzzy patches, and often smells musty. Inhaling mould spores can lead to:
- Coughing or throat irritation
- Nausea
- Respiratory infections (in rare cases)
If in doubt, do not use the medication. Dispose of it and contact your clinic for advice.
How to store Cannabis properly
Good storage helps maintain potency and prevent mould. Focus on controlling these four elements: light, heat, moisture, and oxygen.
- Use airtight glass containers: Avoid plastic. Airtight jars protect trichomes and cannabinoids.
- Keep it cool, dark, and dry: Store below 25°C, away from direct sunlight. Avoid fridges and freezers.
- Control humidity: Keep relative humidity between 59–63% to prevent mould or drying. Use humidity packs.
- Limit air exposure: Open packaging only when necessary and reseal tightly after use.
Why source and quality matter
Properly grown and cured cannabis from licensed medical clinics undergoes rigorous testing for potency, moisture, and contaminants like mould or heavy metals.
- Reliable consistency and potency
- Lower contamination risk
- Safer for long-term storage and use
Can you use old Cannabis?
Dry or slightly aged cannabis may still be effective, albeit with reduced potency. If there’s mould, discolouration, or a strong musty odour, it’s best to discard it.
Final thoughts
Stored correctly, cannabis can remain safe and effective for several months. But over time, it will naturally degrade.
At CB1 Medical, we encourage patients to routinely check their medication. If you ever have concerns about quality or safety, please reach out to your clinic.
Curious if you’re eligible?
Try our free eligibility checker to see if medical cannabis is right for you.
