D20: Degradation of THC in Edibles Over Time

D20: Understanding THC Degradation in Edibles Over Time

As edibles age, their THC potency varies, directly affecting the concentration of THC in the bloodstream upon consumption. Fresh edibles with high THC potency can deliver higher plasma THC concentrations. However, the THC content deteriorates over time, resulting in moderate to low plasma concentrations at 30 and 90 days, respectively. Factors influencing this degradation include exposure to light, heat, and air, and microbial activities. Consumers looking to preserve the potency of their edibles should consider appropriate storage conditions. Old edibles are usually safe to eat but may lack efficacy. Regulations about expiration dates on cannabis products vary by jurisdiction.

The Science Behind THC Degradation in Edibles

The degradation of THC in cannabis-infused edibles is a natural process that can be influenced by a variety of factors. Exposure to light and oxygen can accelerate the degradation of THC into cannabinol (CBN), a compound with distinct properties and reduced psychoactivity. Moreover, heat can also lead to THC degradation, turning it into delta-8-THC or other less potent metabolites (Rosenthal, 1994, p.90-93).

Factors Influencing THC Degradation

  1. Light: Photodegradation occurs when THC is exposed to light, particularly UV light, converting it into less potent compounds (Fairbairn, Liebmann, Rowan, 1976, J Pharm Pharmacol).
  2. Heat: Elevated temperatures can cause decarboxylation or the degradation of THC into other cannabinoids (Rosenthal, 1994).
  3. Oxygen: Oxidation in the presence of air can lead to the breakdown of THC (Trofin, Dabija, Vaireanu, Filipescu, 2012, Rev Chim Bucharest).
  4. Microbial Activity: Although less researched, microbial degradation could also contribute to THC breakdown over time.

Preserving the Freshness of Edibles

To safeguard the freshness and potency of edibles:

  1. Storage: Use airtight containers and store in a cool, dark place.
  2. Temperature Control: Refrigeration can be effective but note that moisture can affect quality.
  3. Oxygen Barriers: Use vacuum-sealed bags to minimize oxygen exposure.

Are Old Edibles Safe?

Edibles that are past their prime in terms of THC potency are generally safe to consume but may lack efficacy. However, if microbial growth or mold occurs, it’s best to avoid consumption.

Regulatory Aspects

Regulations concerning expiration dates on cannabis edibles differ depending on jurisdiction. In some places, expiry dates may be required on the packaging, while in others, it might be optional.

Does Cannabis Expire?

While cannabis itself does not ‘expire’ in the way perishable foods do, its potency and efficacy can diminish over time, rendering it less effective for both recreational and medicinal use.

What You Should Know About Product Age

  1. Efficacy: Older products may have reduced efficacy due to THC degradation.
  2. Safety: Check for signs of spoilage like mold or off-odors.
  3. Legality: Always abide by local regulations concerning cannabis storage and use.


  • Rosenthal, E. (1994). “The Cannabis Grow Bible”. Ed Rosenthal.
  • Fairbairn JW, Liebmann JA, Rowan MG. “The stability of cannabis and its preparations on storage,” Journal of Pharmacy and Pharmacology, 1976;28(1):1–7.
  • Trofin IG, Dabija G, Vaireanu DI, Filipescu L. “The influence of long-term storage conditions on the stability of cannabinoids derived from cannabis resin,” Revista de Chimie (Bucharest), 2012;63(3):293–297.

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