Picaridin repels insects, ticks, and chiggers. It is a synthetic compound first made in the 1980s. It was made to resemble the natural compound piperine, which is found in the group of plants that are used to produce black pepper. Picaridin has been widely used as an insect repellent in Europe and Australia, but has only been available in the United States since 2005.

Picaridin can be used on human skin or clothing to repel mosquitoes, biting flies, ticks, fleas, and chiggers. These products may be pump sprays, liquids, aerosols, or wipes. There are about two dozen products with picaridin in them for sale in the United States.

Picaridin repels insects and makes them less likely to bite. It seems to block mosquitoes from sensing their prey. Picaridin doesn't kill insects.

There are four ways that people can be exposed to chemicals: contacting their skin, contacting their eyes, breathing them in, or eating them. Picaridin is often used directly on skin. It may also be inhaled when sprays are used around the body, especially in indoor spaces where the vapors may remain for some time. If someone doesn't wash their hands after applying an insect repellent and then smokes or handles food, it is possible that they may swallow some picaridin.

Risks can be reduced by always reading the entire label and following all instructions.

When researchers applied picaridin to the skin of rats, 60% of it went through the skin. In humans, less than 6% of the picaridin applied to skin was absorbed. Picaridin may be broken down once it is in the body. Rats and humans excrete almost all of it in their urine within a day of exposure.

Researchers did not see increases in cancer among laboratory animals after putting picaridin on the animals' skin for two years. The U.S. EPA decided that picaridin is not likely to cause cancer based on long-term skin exposure studies in rats and mice.

Researchers applied large amounts of picaridin to the skin of rats and rabbits for up to two years to evaluate any effects on the animals or their offspring. The parent animals' skin got thicker, became irritated, and developed dark spots. There were no effects on the offspring of the treated rats and rabbits. Rats given the highest doses of picaridin had heavier livers. There was no information available on long-term exposure to picaridin in people.

While children may be especially sensitive to pesticides compared to adults, there are currently no data to suggest that children have increased sensitivity specifically to picaridin.

Picaridin is moderately toxic to fish. It may build up in the tissues of some fish. Green algae grown in water with picaridin did not grow as well as algae grown in water without picaridin. Picaridin is considered to be nontoxic to birds.