Neem oil is a natural oil extracted from Azadirachta indica plants. Despite its pungent smell, this oil has many uses. It's found in shampoos, lotions, and soaps, particularly those for soothing skin. Though it's not suitable for cooking, very diluted neem oil does play a part in many traditional medicines, particularly for skin problems. Many farmers also use this oil as a natural selective pesticide, and its ability to repel bugs makes it a common ingredient in natural anti-lice and mosquito formulas.
How It's Made
All neem oil is made from the olive-like fruits and seeds of the neem tree. High quality oils are made by crushing the plant parts, while lower quality ones are made by using solvents to extract the oil. All parts of a neem tree are useful — for instance, neem leaves can also be included in a bath to ease skin conditions — but generally speaking products using one part of a neem tree can't be substituted for products that use other parts. For instance, neem toothpaste can only be made with the bark or leaf extracts of a neem tree, not the oil. This is because ingesting pure neem oil or lots of diluted oil can be toxic, though is generally safe for external use as long as it's used as directed.
Cosmetic and Medicinal Uses
There are neem-based products for both humans and animals. Many people use neem oil shampoo to repel lice and soothe scalp itching and inflammation. It's antibacterial and antiseptic, and will also discourage fungi and parasites, so it's also used in soaps and lotions to soothe and protect skin. These characteristics make neem oil a key part of many traditional medicines as well, particularly for skin conditions like eczema, ringworm, scabies, and athlete's foot. It is also massaged into arthritic joints to relieve pain, and into the scalp to treat dandruff.
A Natural Pesticide
Neem oil is quite popular as a natural pesticide, since it doesn't strongly affect humans, mammals, or beneficial bugs but can keep away pests white flies, aphids, mites, and weevils. It can also strengthen crops against rust, scab, mildew, and blight. Pesticides made with this oil work as "contact" insecticides, which means that they make plants taste bitter so pests won't eat them. Azadirachtin, a chemical in the oil, also interrupts insects' transitions between different stages of metamorphosis, such as growing from larvae to pupae, and prevents insects from developing a hardened exoskeleton. When the chemical gets absorbed through the roots of crops, it functions as a "systemic insecticide," which means crops don't need to be constantly re-sprayed.
The greatest benefit of using neem oil is that it doesn't harm beneficial insects. Butterflies, earthworms, and bees all help plants pollinate or absorb nutrients. Lacewings eat insects trying to feed on the crops. These bugs do not have a negative reaction to neem pesticides or azadirachtin.