Neem oil
Fats and Glyceridic oils, margosa
Neem oil, pressed from the seeds of Azadirachta indica, is best known as a larvicide and plant-protection agent. As a skin repellent for people its record is modest and inconsistent, stronger in some village field trials than in controlled lab tests.
How it works
Neem's activity comes from azadirachtin and related limonoids, which act mostly as insect growth regulators and feeding deterrents rather than as a vapor that keeps mosquitoes away. On skin, any repellency depends heavily on the carrier and concentration.
Safety around dogs & cats
Neem is used in some pet products and is relatively well tolerated topically on dogs at proper dilution, but concentrated oil can cause drooling and stomach upset if ingested, and cats will groom it off, so keep it off cats. Species-specific safety data are limited; dilute and patch test if a vet approves any on-animal use.
Low confidence. Ratings from ASPCA Animal Poison Control, the Pet Poison Helpline, and published veterinary toxicology. This is general information, not veterinary advice. If your pet is exposed, call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.
The evidence
The most-cited human study, a 1995 field trial in India, found 1 to 4% neem in coconut oil gave 81 to 91% protection through a 12-hour night against Anopheles. Later trials report far shorter and more scattered protection, often just a couple of hours, which points to formulation more than a strong intrinsic repellent. Neem's firmer evidence is as a larvicide, not skin protection.
Products using it
Regulatory notes
Source: EPA SRS active ingredient list export. Minimum risk (25(b)) status is applied separately when applicable.
Safety notes
Low-percentage neem is tolerated by most people, but concentrated oil is a known irritant. Undiluted neem can sicken dogs and cats if ingested or heavily applied, so keep it off pets.