Infusing an herb in oil allows its active fat-soluble ingredients to be extracted. Hot infused oils are simmered, while cold infused oils are heated naturally in the sun. Both types of oil can be used externally as massage oils or added to creams and ointments.
Oil Infusion – Hot Method
Many herbs make effective hot infused oils, especially such spicy herbs as ginger, cayenne, and pepper. These oils can be rubbed into the skin to relieve rheumatic and arthritic pain, improve local blood flow, and relax muscles. Other hot infused oils from such leafy herbs as comfrey speed wound healing; mullein is used for earaches and ear infections; and chickweed ointment may also be produced from a hot infused oil.
Oil Infusion – Cold Method
Fill a clear, glass jar with an herb. Cover the herb completely with oil. Close the jar and shake well. Place in a sunny spot and leave for two to six weeks. Strain the oil through a jelly bag or wine press squeezing out as much of the oil as possible. Pour the infused oil into dark glass bottles and label.
This is a slow process and involves leaving a jar packed with herbs and oil to stand for several weeks. Sunlight encourages the plant to release its active constituents into the oil. It is the most suitable method for fresh plant material, especially the more delicate parts as flowers.
St. John’s wort (anti-inflammatory and analgesic) and calendula are the most commonly produced cold infused oils. Olive oil is particularly suitable for cold infusion as it rarely turns rancid. The intensity of the sunlight and length of time an herb is infused affect the concentration of its medicinal constituents. For greater strength, add the extracted oil to a fresh supply of herbs and infuse again.