Health & beauty

Insect repellents

Updated: 07 Dec 2009
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Introduction

What are the alternatives to DEET-based insect repellents and how effective are they?

DEET-based insect repellents have been widely used for more than 50 years – they’re the gold standard for insect repellents. But they have their disadvantages.

We compared 5 non-DEET insect repellents with a standard 30-percent DEET product to see how effective they were.

About our test

Mosquito

Some consumers have been concerned about DEET’s safety (despite few serious problems with its use recorded over the last 50 years). It can also damage plastic items such as sunglasses. And some people don’t like how it smells and feels on their skin.

So what are the alternatives? Two of the five non-DEET products we tested contained a synthetic repellent (picaridin) and the rest were natural. (See Types of repellent for more information.)

We tested:

  • Apex Repel New Era Ultra Pump Spray (picaridin)
  • Kiwicare Safari Organic Insect Repellent Wipes (natural)
  • MozzyOff Midge & Mosquito Repellent Liquid (natural)
  • Skin Technology New Generation Pump Spray (picaridin)
  • Tui Bug Balme (natural)

We haven’t named the DEET product, as DEET-based repellents of the same strength will generally perform similarly.

The test

The repellents were tested on four volunteers in a laboratory. To set a benchmark, each volunteer exposed an untreated arm in a cage containing 200 hungry mosquitoes before testing started.

A specified amount of repellent was then spread evenly on each volunteer’s forearm. The treated arm was exposed to the mosquitoes for three minutes within five minutes of application and then at hourly intervals. At each exposure the lab counted the number of mosquito “landings” and bites. Assessment of a product stopped when all volunteers had received at least one confirmed bite.

See the Test results table to see how all the product performed.

What we found

DEET is best

 

The DEET repellent was the most effective in our test. It was seven hours before any of the volunteers received a bite.

 

Picaridin products

 

The two products containing picaridin (Apex Repel New Era and Skin Technology New Generation) were the best of the non-DEET products. It was two hours before a mosquito attempted a bite on two of the volunteers and three hours before all four received a bite. These two products clearly outperformed the natural repellents.

 

Natural products

 

The natural products offered limited protection. The Kiwicare Safari wipes repelled the mozzies well for a short time after application but a bite was recorded within an hour. The MozzyOff and Tui Bug Balme products offered the least protection.

 

There was some protection, with fewer landings once the products were applied. While you could use them at a backyard barbecue, we wouldn’t advise taking them on the Milford Track – or on a South Pacific holiday during the rainy season.

This was a very demanding test – you’re unlikely to find so many mosquitoes in such close proximity in the wild. So our results should be treated as guidelines. How long a repellent’s effect lasts will depend on the conditions and on your activities – sweating will shorten your protection time.  

 

Where to find them

If you’re having trouble finding a product at a pharmacy, supermarket or health food store you can contact its distributor:

Test results

 Here's how all the products performed:

Insect repellent test results table

Guide to the table 

Our test was carried out in an independent laboratory in Australia. Price is based on a survey in Auckland, Wellington, Christchurch and online during October and November 2009.

Protection ratings are according to the product’s level of protection against the risk of insect-borne disease:

  • Four stars = good level of protection where there is a high risk of insect-borne disease.
  • Three stars = good level of protection where there is a low risk of insect-borne disease.
  • Two stars = should not be used to protect from insect-borne disease. 
  • One star = minimal protection.

 

Types of repellent

Using insect repellent

The US organisation Centers for Disease Control and Prevention (CDC) lists DEET, picaridin and lemon eucalyptus oil as effective insect repellents.

DEET

DEET (N,N-diethyl-m-toluamide) is the most commonly used repellent. It has a long history of safe use and the US Environmental Protection Agency (EPA) has found DEET safe when it’s used according to directions. The CDC says repellents containing 30 to 50 percent DEET are safe to use on children over the age of two months.

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.

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.

Tip: The EPA has expressed concern about products that combine DEET with sunscreen. DEET should be applied sparingly and not reapplied too often, while sunscreen products recommend frequent reapplication – so regular applications of sunscreen may mean you use more DEET than necessary. Mosquitoes are also generally more active in the early morning or evening, times when you are less likely to need sunscreen.

Picaridin

Picaridin is a relatively new repellent that’s less aggressive than DEET. It doesn’t feel sticky or greasy, is less likely to irritate the skin, and doesn’t damage plastic.

Lemon eucalyptus oil

Lemon eucalyptus oil is the most effective natural product. We weren’t able to find a lemon-eucalyptus-oil repellent to include in our test but a Consumer Reports test in the US found it to be as effective (against mosquitoes) as low-concentration DEET products.

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 hasn’t been tested for safety and efficacy.

Other natural repellents

Other natural repellents use plant oils with known or suspected insect-repelling capabilities – such as citronella, lemongrass, eucalyptus or lavender.

We’ve tested natural repellents before, in 2000. Both then and now we’ve found 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.

Protection overseas

Pacific island

Cheap airfares have made travel to faraway places popular, but in some destinations a mosquito bite is much more than an itchy irritation. Malaria, dengue fever, Japanese encephalitis and the West Nile virus are just some of the life-threatening illnesses spread by biting insects.

Pacific risk

The risks of travel in some parts of Asia, Africa and Central or South America are well known. But for Kiwi travellers the biggest risk of dengue fever is in the Pacific Islands. Of the 114 cases of dengue fever notified here in 2008, 32 were people who had been to Tonga, 20 in people returning from Fiji and 25 in those returning from Samoa.

Outbreaks of dengue fever have recently been reported in North Queensland (Cairns, Port Douglas and Townsville).

Staying protected

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 as well as DEET on your body. Permethrin soaks into the fabric and kills insects on contact. Its protection is effective for up to two 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.

More information

 

Report by Bev Frederikson.