You can make oregano-infused oil at home with just fresh or dried oregano, a carrier oil like olive oil, and a few days of patience. The process extracts the herb’s active compounds into the oil, giving you a versatile product for topical use or culinary purposes. There are two main approaches: a slow cold infusion and a faster heat infusion.
Dried vs. Fresh Oregano
Dried oregano is the safer and more reliable choice for making infused oil. Fresh herbs carry moisture, and water trapped in oil creates conditions where harmful bacteria, including the kind that causes botulism, can grow. Low moisture content is essential for a stable, safe product. If you’re starting with fresh oregano from your garden, dry it thoroughly first by hanging bundles upside down in a warm, well-ventilated spot for one to two weeks, or using a dehydrator until the leaves crumble easily between your fingers.
Which Oregano Works Best
Not all oregano is equal. The compounds that give oregano oil its well-known properties, primarily carvacrol and thymol, vary dramatically depending on the species and growing conditions. Greek oregano (Origanum vulgare) is the most commonly available and a solid choice. Turkish oregano (Origanum onites) is another good option.
To give you a sense of how much variation exists: studies on Mexican oregano species found carvacrol content ranging from about 24% in cultivated winter plants to over 50% in wild autumn plants. Thymol ranged from roughly 6% to 16% depending on whether the plant was wild or cultivated and what season it was harvested. The takeaway is simple: buy oregano labeled as Origanum vulgare from a reputable source, and if possible, choose organic herbs that haven’t been irradiated, since the processing can reduce the potency of volatile compounds.
Cold Infusion Method
This is the easiest approach and requires no special equipment.
- Step 1: Lightly crush or bruise about half a cup of dried oregano leaves. This breaks open the plant cells and helps release the oils.
- Step 2: Place the crushed oregano in a clean, dry glass jar.
- Step 3: Pour in roughly one cup of carrier oil, enough to fully submerge the herbs with about an inch of oil above them. Extra virgin olive oil is the most popular choice because it’s shelf-stable and has its own mild antimicrobial properties, but grapeseed or sweet almond oil also work.
- Step 4: Seal the jar tightly and place it in a warm, sunny windowsill. Shake it once daily.
- Step 5: After two to three weeks, strain the oil through cheesecloth or a fine mesh strainer into a clean, dark-colored glass bottle. Squeeze the cheesecloth to extract every last drop.
The longer the herbs steep, the more concentrated the final product. Two weeks is the minimum for a reasonably potent infusion; three to four weeks produces a stronger oil.
Heat Infusion Method
If you don’t want to wait weeks, gentle heat speeds up extraction significantly. You can have a finished oil in a few hours.
- Step 1: Combine crushed dried oregano and carrier oil in the same ratio (roughly half a cup of herb to one cup of oil) in a double boiler or a heat-safe glass bowl set over a pot of simmering water.
- Step 2: Keep the oil at a low, steady temperature for two to three hours. You want it warm to the touch but never smoking or bubbling. If you have a thermometer, aim for around 100 to 150°F (38 to 65°C).
- Step 3: Remove from heat, let it cool completely, then strain into a dark glass bottle.
The heat method trades some subtlety for speed. High temperatures can degrade delicate volatile compounds, so keep the heat gentle. If the oil starts to smell burnt or acrid, the temperature is too high.
What Oregano Oil Actually Does
The two key active compounds in oregano, carvacrol and thymol, work by disrupting the outer membranes of bacteria. They essentially punch holes in the bacterial cell wall, causing the cell to lose its internal pressure and die. Lab studies have confirmed that both compounds at relatively low concentrations can inhibit common bacteria like E. coli by permeabilizing and depolarizing their cell membranes.
It’s worth noting that a homemade oregano-infused oil is significantly less concentrated than the commercial essential oil you’d buy in a small dropper bottle. Commercial oregano essential oil is produced through steam distillation, which isolates the volatile compounds in a highly concentrated form. Your homemade version is an infusion: the active compounds are dissolved into a carrier oil, making it milder and generally safer for direct use.
Storage and Shelf Life
How you store your oregano oil determines how long it lasts and whether it stays safe. According to the University of Georgia Cooperative Extension, non-acidified infused oils (which is what most homemade oregano oils are) should be refrigerated and used within four days. Alternatively, you can freeze the oil in small portions until you’re ready to use it.
That four-day guideline is conservative and geared toward food safety, particularly the botulism risk that comes with garlic and other low-acid ingredients in oil. Dried oregano carries less risk than fresh garlic, but the safest practice is still refrigeration. For longer shelf life, the University of Idaho developed an acidification method that brings the pH below 4.2, which allows room-temperature storage. This involves soaking the herbs in citric acid solution before infusing, though the added acidity slightly changes the flavor.
Regardless of method, store your finished oil in dark-colored glass bottles and keep it away from heat and light. Oils oxidize and turn rancid faster when exposed to either. If the oil smells off, looks cloudy, or develops any visible mold, discard it.
Safe Use on Skin
Oregano is one of the more irritating essential oil sources. Its high carvacrol content makes it a potential skin sensitizer, and undiluted oregano oil should never be applied directly to skin. Even your milder homemade infusion can cause redness or rash in sensitive individuals.
If you plan to use your infused oil topically, test a small amount on the inside of your forearm first and wait 24 hours. For body applications, general guidelines from the Tisserand Institute suggest essential oil dilutions of 1 to 3% for body oils and lotions. Since your homemade infusion is already diluted in a carrier oil, it’s inherently less concentrated than pure essential oil, but caution is still warranted if you have sensitive or broken skin.
Who Should Avoid Oregano Oil
Pregnant women should not use oregano oil in medicinal amounts, as the active compounds can potentially reach the fetus or stimulate uterine contractions. People taking blood thinners or diabetes medications should also be cautious, since oregano may interact with both. Anyone on lithium should avoid it entirely. And if you’re allergic to plants in the mint family (basil, lavender, marjoram, sage, thyme), you may react to oregano as well, since they’re closely related. In large doses, oregano oil can be toxic, so more is not better.