​  Limonene is a monocyclic monoterpenoid and one of two major compounds formed from pinene. As the name suggests, varieties high in limonene have strong citrusy smells like oranges, lemons and limes. Strains high in limonene promote a general uplift in mood and attitude. This citrusy terpene is the major constituent in citrus fruit rinds, rosemary, juniper and peppermint, as well as in several pine needle oils.
Limonene is highly absorbed by inhalation and quickly appears in the bloodstream. It assists in the absorption of other terpenes through the skin and other body tissue. It is well documented that limonene suppresses the growth of many species of fungi and bacteria, making it an ideal antifungal agent for ailments such as toenail fungus. Limonene may be beneficial in protecting against various cancers, and orally administered limonene is currently undergoing clinical trials in the treatment of breast cancer. Limonene has been found to even help promote weight-loss.
Plants use limonene as a natural insecticide to ward off predators. Limonene was primarily used in food and perfumes until a couple of decades ago, when it became better known as the main active ingredient in citrus cleaner. It has very low toxicity and adverse effects are rarely associated with it.
  

WHAT DOES LIMONENE TREAT?
With its antifungal, antibacterial, antioxidant, and anti-inflammatory properties, there’s little limonene can’t treat. Here are just a few examples of health issues it helps with.
  • Heartburn and gastric reflux: In a study of 19 heartburn patients, 17 had no symptoms after swapping pharmaceutical medications for limonene.
  • Weight loss: By reducing blood pressure, heart rate, and blood sugar while increasing antioxidant levels, limonene cuts fat, cholesterol, and overall appetite to promote weight loss.
  • Skin repair: Though it can cause skin irritation in high doses, limonene generally reduces damage, inflammation, and rashes while improving circulation.
  • Gallstones: Taken every other day in high concentrations, limonene can dissolve gallstones completely.
  • Pain: In rats and mice, limonene reduces pain (and sensitivity to pain) in muscles and bones. Studies have also tested it as an aromatherapy agent for pregnant women, who report reduced pain, nausea, and vomiting.
  • Anxiety: By interacting with serotonin receptors in the brain, limonene can reduce anxiety and stress.
  • Cancer treatment and prevention: Like several other terpenes, limonene shows signs of blocking cancer-forming chemicals. Studies say it may slow the growth of prostate, breast, stomach, and liver cancers (but we still need more research).

Limonene is also added to medicinal ointments and creams to help other ingredients penetrate the skin.

Fragrance-wise, the interesting thing about limonene is that it’s highly volatile (jargon for “easily evaporates into a gas”). That’s what makes pure limonene oil ideal for inhaled aromatherapy, for those who’d rather not smoke it.
But in cannabis – whether you buy high-limonene strains or add pure limonene extracts to your flower – you get the added benefit of enhancing other parts of the plant to treat more (or more complex) health conditions. For example, limonene’s anti-inflammatory and antibacterial effects can boost similar properties in CBD.
Again, researchers are still figuring out how various cannabis components synergize with each other and the body’s own defenses, but terpenes show undeniable promise.