Terpenes play a major role in the therapeutic effects of cannabis, but the same terpenes in cannabis are also found in other plants. Linalool, for example, is found in some cultivars of cannabis but is also produced in high percentages by lavender. Limonene tends to give some cannabis a citrusy aroma, which makes sense, considering it’s also found in lemons and oranges.
The therapeutic benefits of these and other terpenes are well documented. Many studies have proven that terpenes from cannabis and other plants have anti-inflammatory, anti-plasmodial, antiviral, anticancer, antidiabetic, antidepressant, and several other beneficial properties.  Because of the important medical benefits of terpenes, and the fact that natural cannabis terpenes are often degraded or lost during many extraction methods, terpenes extracted from other plants, like lavender and lemons, are often added into products like edibles, oils, and concentrates.
Terpenes seem to have the same effects on consumers regardless of being sourced from either cannabis or other botanicals, but there is little-to-no research comparing the effectiveness of cannabis terpenes against non-cannabis terpenes, like measuring and comparing the effectiveness of a specific enantiomer of linalool extracted from lavender against the same enantiomer of linalool extracted from cannabis. Without any definitive research, it’s difficult to say with certainty whether or not terpene source matters for blends and infusions, but the general consensus is that the therapeutic effects are essentially the same from plant to plant, so long as we’re discussing the same terpene stereochemistry.
The debate generally centers on the fact that it is easier to create standardized blends with outsourced terpenes. Terpene composition can vary, after all, within the same plant and cultivar due to volatility, plant complexity, and the plant’s growing environment. Terpenes from other plants can provide higher concentrations and bolder, distinct flavors, some even imitating cannabis cultivars. They are also more affordable; as True Terpenes points, out, “Pine needles are far cheaper than cannabis and hemp.” On the other hand, high concentrations of isolated terpenes may not match the full spectrum and flavor of a cultivar’s terpenes; they may be considered unnatural and even unsafe.
Phytol is a terpene commonly used in the vape industry. It’s found in cannabis and other plants. It’s often added to vape oils as a thinning agent. A recent study, published this year, found that inhalation of 5 mg/L phytol (but not propylene glycol) in vivo resulted in body weight loss and mortality in rats after one or two exposure days; researchers noted increased lung weight and tissue damage, “demonstrating dose-responsive tissue degeneration, necrosis, edema, hemorrhage and inflammation.”  For this reason, phytol is not recommended for use in vaping products. The study did not confirm whether the phytol used in the study was extracted from cannabis or another botanical.
This danger with phytol in vaping products is enough evidence to confirm that ingestion of certain terpenes in sufficient quantities can have negative side effects and should be further studied. The source of terpenes could present another variable affecting the potential positive or negative side effects of consuming terpenes, and more research is warranted.
1- Cox-Georgian D, et al. Therapeutic and medicinal uses of terpenes. In: Joshee N, Dhekney S, Parajuli P, eds. Medicinal Plants: From Farm to Pharmacy. 2019:333–359. https://doi.org/10.1007/978-3-030-31269-5_15 Times Cited: 25 (Semantic Scholar)
2- Schwotzer D, et al. Phytol, not propylene glycol, causes severe pulmonary injury after inhalation dosing in Sprague-Dawley rats. Inhalation Toxicology.2021;33(1):33-40. https://pubmed.ncbi.nlm.nih.gov/33441006/ Times Cited: 1 (Semantic Scholar) Journal Impact Factor: 2.266