With two new options available and mosquito season approaching, experts say they want consumers to understand what's available to them. Below are the choices, as well as a roundup of evidence.
Has generally been found to be safe for human use; few adverse effects from exposure to DEET have been found, according to the National Pesticide Information Center. The maximum DEET concentration suggested for infants and children is 30 percent, according to recommendations issued by the American Academy of Pediatrics.
A 2002 study published in the New England Journal of Medicine found that higher concentrations of DEET worked for longer periods than lower concentrations. For example, a product containing 6.65 percent DEET lasted about two hours, while one with 23.8 percent DEET lasted about five hours. The authors concluded that DEET provided "complete protection for the longest duration" compared with 12 non-DEET products.
Oil of lemon eucalyptus (p-menthane 3,8-diol or PMD)
A plant-based ingredient that protects as effectively as low-concentration DEET repellents, according to the Centers for Disease Control and Prevention. Not approved for children under 3. Has a more pleasant odor than DEET. The evidence backing oil of lemon eucalyptus as a repellent is not as strong as the data supporting picaridin and DEET. It may need to be reapplied every few hours.
A 2003 study published in Phytotherapy Research comparing the effectiveness of oil of lemon eucalyptus and DEET with other ingredients found that the plant repellent and DEET performed better at 75 percent concentration than two others.
Picaridin (KBR 3023)
Has been used in Europe, Australia, Latin America and Asia for several years. One U.S. product, Cutter Advanced Insect Repellent, contains 7 percent picaridin. It is considered as safe and effective as DEET products at similar concentrations, according to the CDC. It doesn't have an odor.
A University of Rome study, published in the Transactions of the Royal Society of Tropical Medicine and Hygiene last year, found that picaridin outperformed DEET repellents after 10 hours of exposure to four species of mosquitoes. An Australian study published last year in the Journal of Medical Entomology found that 19.2 percent picaridin performed nearly as well as a gel containing 35 percent DEET and a solution with 20 percent DEET.