DEET-based insect repellents are the gold standard for insect repellents. But they have their downside. So are the alternatives catching up? We tested 4 DEET and 3 non-DEET products.
Snapshot: The Mosquito Band Anti-insect Band is a wrist-band insect repellent that uses citronella oil as the active ingredient. How long does it last?
Snapshot: The RID Medicated Repellent Plus Antiseptic Spray is an aerosol insect repellent that uses DEET as the active ingredient. How long does it last?
Snapshot: The Aerogard Odourless Low Irritant is an aerosol insect repellent that uses picaridin as the active ingredient. How long does it last?
Snapshot: The Bushman Plus Personal Insect Repellent 20% DEET with Sunscreen is an aerosol insect repellent that uses DEET as the active ingredient. How long does it last?
Snapshot: The Bushman Plus Personal Insect Repellent 40% DEET Heavy Duty is an aerosol insect repellent that uses DEET as the active ingredient. How long does it last?
Snapshot: The Aerogard Tropical Strength Insect Repellent is an aerosol insect repellent that uses DEET as the active ingredient. How long does it last?
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Two of the non-DEET products contained a synthetic repellent (picaridin) and one used a “natural” repellent, citronella oil.
6 insect repellents in our test were aerosol sprays and one was a wrist band. They claimed to be effective from 3 to 6 hours.
Each repellent was tested on 4 volunteers in a laboratory. Each volunteer had a specified amount of repellent spread evenly on one forearm, while their other arm was left untreated as a control. Both arms were placed in a cage containing around 50 hungry mosquitoes for a set number of exposures depending on the product’s claimed length of effectiveness.
At each exposure the lab counted the number of mosquito “landings” and “probing of the skin”. These exposures lasted 1 minute and took place at intervals of 15, 120, 180, 240 and 360 minutes depending on the claims of the repellent (the Bushman repellents claimed to last longer than 6 hours). Each mosquito was removed before biting took place.
DEET (N,N-diethyl-m-toluamide) is the most commonly used repellent. It has a long history of safe use and the EPA has found DEET safe when it’s used according to the product’s directions. The CDC says repellents containing DEET are safe to use on children over the age of 2 months. However, the American Academy of Pediatrics (AAP) has recommended DEET levels of no higher than 30 percent when used on children.
The concentration of DEET in a repellent can go as high as 80 percent (concentrations above 50 percent may last longer but provide no added protection). You shouldn’t use too much of it or for too long and you shouldn’t apply it over broken skin or under clothing. Never spray insect repellent directly to your face; instead spray it into your hands first and rub it on. Wash your skin with soap and water after coming indoors.
In more than 50 years’ use there have been fewer than 50 cases of significant reactions to DEET, and these are usually associated with swallowing the repellent or with long-term heavy or whole-body use. But some people could experience skin problems, especially if they use it in high concentrations or in large quantities for several days. DEET may damage synthetic fibres and plastics.
Picaridin is a relatively new repellent that’s less aggressive than DEET. It has little odour, doesn’t feel sticky or greasy, is less likely to irritate the skin, and doesn’t damage plastic.
Lemon eucalyptus oil is the most effective natural product. We weren’t able to include a lemon-eucalyptus-oil repellent in our test.
The CDC warns that its recommendation on lemon eucalyptus oil’s effectiveness applies only to repellents containing the oil as an ingredient – pure oil of lemon eucalyptus (essential oil not formulated as a repellent) hasn’t been tested for safety and efficacy.
Other natural repellents use plant oils with known or suspected insect-repelling capabilities – such as citronella, melaleuca, lemongrass, eucalyptus or lavender.
We’ve found in past tests that they have some initial repellent effect but it diminishes rapidly. If you prefer to use a natural product, you need to reapply it regularly. And never rely on it where there’s a risk of insect-borne disease such as malaria or dengue fever.
Caitlin Plummer from The Travel Doctor strongly advises travellers to use insect repellents and to follow techniques for insect avoidance.
This is to protect against insect-borne diseases like malaria, dengue fever and yellow fever. She recommends a 30 percent DEET product or a 20 percent picaridin product to her patients. In some cases she will suggest a product with higher doses of DEET depending on where the person is going.
The risks of travel in some parts of Asia, Africa and Central, South America and the Pacific Islands are well known.
Travellers in these areas should use DEET at a concentration of 30 to 50 percent. If you’re adventure-trekking or spending time away from resorts you’ll need even more protection. Clothing which covers as much of the body as possible – long-sleeved shirts and trousers – will reduce the amount of DEET you need to use.
For maximum protection, use permethrin on your clothing or mosquito nets as well as DEET on your body. Permethrin soaks into the fabric and kills insects on contact. Its protection is effective for up to 2 weeks, even through several washes. Permethrin soaks and sprays for treating clothing, tents and mosquito nets are sold by some tramping and outdoor supplies stores and by travel medicine clinics. You can buy mosquito nets pre-treated with permethrin.
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