Natural Insect Repellent

Picaridin and natural insect repellents

Clinical tests all conclude that insect repellents using DEET as their active ingredient are effective. However, DEET has an off-putting smell and doesn't feel good on the skin. DEET is also a solvent for which improper use is risky, and in higher concentrations, it can ruin clothing, plastic and paint finishes. Therefore, many question whether DEET is the safest thing to put on your skin. Some researchers and pediatricians warn that even using DEET according to the label instructions may pose health risks. Noting an association with seizure incidents among children, the Environmental Protection Agency (EPA) categorizes DEET as "slightly risky."

While DEET has been around for decades, scientists did not know exactly how it worked until recently. Researchers at Rockefeller University helped to discover that DEET blocks the odors that attract insects to humans. The importance of this discovery is significant both for understanding the chemical and fueling further research. Now that scientists know how the chemical affects insects, they will be able to develop better and more effective alternatives to DEET.

Some alternative insect repellents smell and feel better then DEET; they cause less damage and are more pleasant to use, but no alternative to DEET has been shown to be as effective, especially against mosquitoes. The main drawback to these DEET-free insect repellents is that you may need to reapply them more often, and that each ingredient has advantages and drawbacks.

Types of repellents

DEET: Chemical that's effective against mosquitoes, some flies, gnats and ticks. Safety is well-studied but controversial. It works well for most people but has a bad smell and doesn't feel great on the skin. It can damage plastics, paint and synthetic fabrics, and should be washed off after use.

Picaridin: Synthetic; effective against mosquitoes, but not gnats. Doesn't harm clothing or plastic and is safe for kids over two months old. Protects for about 2.5 hours and is odorless. Works better for some people than others.

Lemon eucalyptus oil: Natural insect repellent but can't be used by kids under 3 years old. Protects against mosquitoes, gnats and ticks. Lasts from four to eight hours. Doesn't damage plastic or fabric, but can stain leather. Some people don't like the smell, and it's more effective for some people than others.

Geranium/soybean oil: Natural mosquito repellent, safe for kids as young as 2 months old. Doesn't damage clothing or plastics, but isn't as effective as DEET, lemon eucalyptus oil or picaridin. Not everyone likes the smell, it can feel sticky, and herbal insect repellents do not work as well for some people as others.

One of the main advantages of insect repellents that use picaridin is that they don't smell bad, and they also feel better on the skin. Unlike DEET, picaridin-based mosquito repellent doesn't need to be washed off your skin when you return indoors, and it doesn't damage plastics or synthetic fabrics. Experts consider it safe for kids, pregnant women and even for babies at least two months old.

The World Health Organization recommends picaridin as the best mosquito repellent against malaria, because it's less apt to irritate skin than DEET. As with DEET, the length of time a picaridin insect repellent protects completely against bites depends on its concentration. Picaridin is derived from a pepper, and though it doesn't usually irritate the skin, it can cause eye irritation. The review at Slate magazine reports that it actually attracts gnats. The relatively low concentrations available in the United States don't protect as long as 25 to 35 percent DEET insect repellents, so for longer exposures you have to apply it more often.

Best non-DEET insect repellents

Although picaridin insect repellents available in other countries use higher concentrations, only low-concentration products are available in the United States. Cutter Advanced Sport (*Est. $5.50 for 6 oz.) has 15 percent picaridin, but it is only to be applied once a day. More reviews recommend the 7 percent picaridin version, Cutter Advanced (*Est. $6 for 6 oz.), which may be applied up to three times a day, making it a more versatile mosquito repellent. We found no reviews of OFF! FamilyCare Insect Repellent II Clean Feel (*Est. $5 for 6 oz.), which contains just 5 percent picaridin.

Some tests show that only the 15 percent picaridin Cutter Advanced Sport protects against the most aggressive Aedes mosquitoes (found mostly in the tropics, but in some parts of the southern United States as well). Both versions of Cutter Advanced are effective against Culex mosquitoes, the type that can carry the West Nile virus. Because the manufacturer recommends applying Cutter Advanced Sport mosquito repellent only once a day, while the 7 percent picaridin Cutter Advanced insect repellent may be applied up to three times, the 7 percent is a more versatile choice.

For stronger, longer-lasting protection, Repel Lemon Eucalyptus (*Est. $7.50 for 4 oz.) is a botanical (plant-based) insect repellent suitable for adults and children at least 3 years old. Repel Lemon Eucalyptus is a pump spray with 30 percent lemon eucalyptus oil plus a little alcohol (less than 10 percent); the other ingredients are unspecified.

The main advantage of Repel Lemon Eucalyptus over picaridin insect repellents is that it repels gnats as well as ticks and mosquitoes, and because it's available in the United States in higher concentrations, it offers longer protection per application. Protection time averages about as long as a 25 percent DEET mosquito repellent -- four to eight hours, depending on the species of mosquito. However, comparison reviews show that protection time varies more among individuals than with DEET, which pretty much works for everyone. Although lemon eucalyptus oil does not damage plastics, paint finish or synthetic fabrics the way DEET does, it can stain leather. Most, but not all reviewers, like the fragrance of Repel Lemon Eucalyptus, although it doesn't feel as clean on the skin as picaridin; some say it has a tacky feel.

No health problems have been associated with lemon eucalyptus oil, and the Centers for Disease Control recommend this natural insect repellent for protection against mosquito-borne diseases. Like any insect repellent (natural or otherwise), it should first be tested on a small area of skin to make sure it doesn't cause an allergic reaction.

Although reviews say an active ingredient called IR3535 is reasonably effective as an insect repellent, it's easier to find in Europe. In the United States, Avon combines it with sunscreen in Avon Skin So Soft Bug Guard Plus IR3535 (*Est. $11.50 for 4 oz. lotion). But the EPA and other experts recommend using two separate products instead of one that combines sunscreen with insect repellent. A University of Florida study shows that the repellent in combination products gets absorbed into the skin more than in repellent-only products. Because this Avon insect repellent uses IR3535 rather than DEET, that reasoning may not apply here. However, experts also say that sunscreen should be applied more often than insect repellent, in order to minimize exposure to the latter.

Quite a few other active ingredients are being studied by various researchers. Neem oil looks promising, for example, but it is not available in the United States as a commercial insect repellent product. Isolongifolenone, a natural compound found in South American Tauroniro trees, has been shown to be as effective as DEET in repelling mosquitoes and ticks in preliminary tests. It has not yet been approved, however, for use in the U.S.

Comparison tests that include botanical insect repellents show that while some work well for some people, it's impossible to predict before trying one whether or not it will prove worth the money. (Lemon eucalyptus oil and Bite Blocker are the best plant-based bets for most people.) And just because a product is plant-based doesn't make it safe -- think of poison ivy and deadly nightshade.

In fact, botanical repellents are as apt to cause allergic reactions as any other insect repellent. For example, Canada is phasing out the use of both citronella and oil of lavender, because of established health risks. Experts say it's especially important to avoid plant oils that are apt to be "sensitizers," meaning that they may cause a heightened allergic reaction to many other substances as well. This is how chemically sensitive people become allergic to ingredients that caused them no problems earlier.

Natural insect repellent for kids

For children as well as adults, Canadian health authorities recommend soybean-oil-based insect repellents like Bite Blocker (*Est. $8.50 for 4.7 oz.), which is also recommended by the American Pediatrics Academy. Bite Blocker is the most recommended natural insect repellent, because it uses only food-grade, renewable, plant-based ingredients. Although soybean oil itself has some ability to repel insects, Bite Blocker adds quite a few other ingredients to enhance its effectiveness, including vanillin and geranium oil. In comparison tests, Bite Blocker's proprietary mix consistently outperforms other natural insect repellents, except for Repel Lemon Eucalyptus. However, as with Repel, Bite Blocker is more effective for some people than others.

Reviews say Bite Blocker natural mosquito repellent is approximately as effective as a 7 percent DEET repellent against ticks and Culex mosquitoes -- about 90 minutes to two hours -- but is safe to reapply. Tests against more aggressive Aedes mosquitoes give mixed results. One review shows no protection, while the U.S. Department of Agriculture test against four different species shows Bite Blocker protects as long as Repel Lemon Eucalyptus. The informal review at Slate.com notes that while Bite Blocker feels cool when applied, it also feels sticky (not surprising, because it's oil-based), and it stings on cuts. (Most reviews warn against applying any insect repellent over cuts.)

We found more than one review recommending Buzz Away Extreme natural insect repellent (*Est. $7 for 4 oz.), which uses a different blend of soybean and geranium oils than Bite Blocker, and Burt's Bees Herbal insect repellent (*Est. $8 for 4 oz.), which uses lemongrass and citronella oil. In user reviews, some people report that the Burt's Bees mosquito repellent has an unpleasant oily feeling, and others claimed that while it helped repel mosquitoes, it attracted other insects.