Making comfrey oil is a simple process: you steep dried comfrey leaves or roots in a carrier oil for several weeks, strain the plant material out, and bottle the finished oil. The whole process takes about 4 to 6 weeks with the cold method, or 2 to 3 weeks if you use gentle heat. The result is a topical oil rich in allantoin, a compound that supports skin cell turnover and tissue repair.
Why Comfrey Works as an Infused Oil
Comfrey root contains between 0.6% and 4.7% allantoin, a compound that stimulates cell proliferation and helps skin repair itself faster. It also contains rosmarinic acid (up to 0.2%), which has anti-inflammatory properties. When you steep the plant material in oil, these fat-soluble compounds transfer into the carrier oil, creating a therapeutic preparation you can apply directly to skin for bruises, sprains, sore muscles, and minor irritation.
Comfrey oil is strictly for external use. The plant contains pyrrolizidine alkaloids that can damage the liver if ingested, and most herbalists recommend avoiding it on deep or puncture wounds. Allantoin speeds surface healing so effectively that it can cause the outer layer of skin to close before deeper tissue has healed underneath, potentially trapping infection.
Leaves, Roots, or Both
You can use comfrey leaves, roots, or a combination. Roots have a higher concentration of allantoin, making them the stronger choice for a repair-focused oil. Leaves are easier to harvest and dry, and they still produce an effective infusion. If you’re growing your own comfrey, leaves can be harvested multiple times per season without disturbing the plant. Roots require digging up part of the plant, so they’re typically harvested in fall when the plant is dormant and the root’s active compounds are most concentrated.
Whichever you choose, chop or grind the material finely before infusing. More surface area means better extraction.
Dried vs. Fresh: Moisture Matters
Dried comfrey is the safer choice for oil infusions. Fresh plant material introduces water into the oil, and that moisture creates conditions for mold and, more seriously, botulism. The anaerobic (oxygen-free) environment inside a sealed jar of oil is exactly where the botulism bacterium thrives when water is present.
If you want to use fresh leaves, there are workarounds. Let them wilt overnight to shed excess moisture. Some herbalists lightly spray fresh leaves with vodka and let them sit for an hour before adding them to oil, which helps displace water. Do not wash the leaves right before infusing, as that adds even more moisture. Cover the jar with cheesecloth or a piece of cotton fabric secured with a rubber band instead of a sealed lid. This lets residual moisture escape as the infusion sits. Make sure the plant material stays fully submerged in oil at all times.
For a first attempt, drying your comfrey completely eliminates these risks. Spread leaves on a screen or hang them in bundles in a warm, dry area with good airflow. They’re ready when they crumble easily between your fingers.
Choosing a Carrier Oil
Olive oil is the most common carrier for comfrey infusions. It’s shelf-stable, affordable, absorbs well into skin, and has a long tradition in herbal preparations. Other good options include sweet almond oil, jojoba oil, and sunflower oil. Jojoba has the longest shelf life since it’s technically a liquid wax and resists going rancid. Avoid oils that spoil quickly, like grapeseed or flaxseed, unless you plan to use the finished product within a few weeks and store it in the refrigerator.
Cold Infusion Method
This is the traditional approach and requires no equipment beyond a jar.
- Ratio: Place 4 ounces (113 grams) of finely chopped or ground dried comfrey in a clean, completely dry quart jar. Pour your carrier oil over the herb until the oil level sits 1 to 2 inches above the plant material.
- Seal and store: If using fully dried material, cap the jar tightly. Place it in a warm spot out of direct sunlight, like a cupboard near a heat source or on top of a refrigerator. A sunny windowsill works too, though direct light can degrade some compounds over time.
- Shake daily: Give the jar a gentle shake once a day to redistribute the plant material and encourage extraction.
- Duration: Let the infusion sit for 4 to 6 weeks.
- Strain: Pour the oil through cheesecloth or a fine mesh strainer into a clean, dry bottle. Squeeze the cheesecloth to get every last drop. Compost the spent plant material.
Check the jar periodically. If you see any fuzz, cloudiness, or off smell, the batch has gone bad and should be discarded. This almost always traces back to moisture contamination.
Warm Infusion Method
Heat speeds up extraction significantly, cutting the infusion time to 2 to 3 weeks or even a single day depending on how much heat you apply.
For a slow warm infusion, combine 2 cups of cut comfrey leaves with 4 cups of olive oil in a slow cooker, double boiler, or oven-safe jar set in a water bath. Maintain a steady temperature around 110°F (43°C). At this temperature, the oil stays well below its smoke point and the allantoin transfers gradually without being damaged by excess heat. Keep it at this temperature for anywhere from 2 to 3 weeks (checking the water level in your double boiler or slow cooker regularly) or for a concentrated single-day extraction of 6 to 8 hours.
For a faster stovetop method, use the lowest burner setting on a double boiler. Stir occasionally and monitor the temperature. You don’t want the oil to simmer or bubble. If it’s too hot to touch the outside of the jar comfortably, it’s too hot for the infusion. After several hours, the oil will darken to a deep green, signaling that extraction is well underway. Strain while the oil is still warm, as it flows more easily through cheesecloth.
Storage and Shelf Life
Pour your finished comfrey oil into dark glass bottles, amber or cobalt blue, to protect it from light degradation. Store in a cool, dark place. A properly made infusion in olive oil keeps for about one year. Adding a few drops of vitamin E oil (sold as a supplement in liquid form) acts as a natural antioxidant and can extend shelf life by a couple of months.
Label each bottle with the date, the plant material used, and the carrier oil. If the oil develops a rancid smell at any point, discard it.
Using Your Comfrey Oil
Apply comfrey oil directly to unbroken skin over sore muscles, stiff joints, bruises, or minor strains. Massage it in gently. Many people use it as the base for a homemade salve by melting beeswax into the warm oil (roughly 1 ounce of beeswax per cup of oil), which gives it a thicker, more portable consistency.
Keep applications to intact skin and limit use to a few weeks at a time. Avoid covering large areas of the body, and don’t use it on children under 12 without guidance from an herbalist or practitioner familiar with the plant.