Mozzies bite? Here’s how to choose a repellent (and how to use it for best protection)

Mosquitoes are an inevitable part of Australian summer. And this year, given COVID, we may be spending more time outside than usual.

Supermarkets and pharmacies are stocked with a wide range of insect repellents, including aerosols, creams, gels, sprays, covers and wipes. There are even bracelets, fabric sprays, coils, sticks, attachments and smartphone apps.

But not all products that protect us from mosquito bites are the same.

So how do you choose and use the repellent that best protects you and your family from mosquito bites?

Key ingredients

Health authorities across Australia recommend the use of insect repellents that you apply directly to exposed skin to prevent mosquito bites and reduce the risk of mosquito-borne diseases.

All insect repellents sold in Australia must be registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA), which checks that the products are safe and effective.

Despite the wide range of formulations available, there are only a small number of active ingredients registered for use. So every insect repellent on the shelves in Australia will contain at least one of these ingredients.

Spending more time outdoors means a greater chance of mosquito bites.
David Todd McCarty / Unsplash

Diethyltoumide (DEET) is one of the most commonly used and recommended repellents worldwide. It effectively prevents mosquito bites and has been repeatedly shown to have minimal harmful side effects if used as directed.

DEET formulations in Australia are available in various concentrations, from only 10% to products for “heavy use” or “tropical strength” which can be up to 80%.

Picaridin it is a common ingredient in topical mosquito formulations and effectively reduces mosquito bites. Like DEET, it has been estimated to be safe to use. Most formulations in Australia have concentrations of less than 20%.

Lemon eucalyptus oil is becoming more common with mosquito repellents. The chemical, p-methane-3,8-diol, is derived from the leaves of a lemon-scented rubber Corymbia citriodora.

This ingredient is a by-product of the distillation process, not an essential oil extracted from the leaves of the plant. This is important because this product is a much more effective repellent than essential oils (we will come up with these alternatives soon).

Formulations containing lemon eucalyptus oil provide comparable protection with DEET-based repellents.

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The active ingredient of the repellent will be listed on the package, along with the concentration.

Any insect repellent containing these products should provide protection against mosquito bites. But the stronger the formulation, the longer the protection will last.

If you’re only out for a few hours, say, in the backyard, you don’t really need a high-concentration formulation. But if you go on a long walk or fishing, choose a product of high concentration (regardless of the active ingredient).

Mosquitoes are one of the most common insect pests in Australia.
A / Prof Cameron Webb (NSW Health Pathology)

It also matters how you use it

Applying here and there, or spraying the repellent into the air around you, as you could perfume, will not provide much protection.

These products should be applied thinly and evenly to all exposed areas of the skin. Imagine repellents camouflaging us from mosquitoes in search of blood.

Although aerosol or pump spray can allow application directly from the container, you will need to rub creams, applications and gels into the skin.

That doesn’t necessarily mean one is better than the other. But when choosing a formulation, think about which one you will consider the easiest procedure.

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What about ‘natural’ alternatives?

Some “natural” preparations containing tea tree oil and other active plant-based ingredients have APVMA registration. Products sold in local markets or online may not be registered.

It is important that products containing plant-based repellents generally do not provide long-term protection against mosquito bites.

If you prefer to use products that contain tea tree oil or other botanical repellents, you must be prepared to re-apply much more often than with DEET, picaridine or lemon eucalyptus oil.

And avoid creating insect repellents from essential oils yourself. Without checks associated with repellents registered for APVMA, there may be a higher risk of adverse skin reactions.

Mosquito repellents come in a variety of formulations.
A / Prof Cameron Webb (NSW Health Pathology)

Can anything else help?

There is no evidence that bracelets will repel mosquitoes or that smartphone apps protect you from mosquito bites.

A range of candles, spools, sticks, plugs and fans and insecticide-treated clothing provide a variety of help in reducing mosquito bites. But unfortunately, none of them provide complete protection and are always best combined with local mosquito repellents.

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Some people pose a so-called “chemical” repellent to our health. But in most cases they can be safely applied to all persons older than 12 months. (It’s best to provide physical protection for babies, such as covering the stroller with a mosquito net.)

It is often said that these traditional repellents are uncomfortable to use. But while the active ingredients haven’t changed much, the cosmetic ingredients of insect repellents have greatly improved in recent years.

To spend the summer, choose a repellent formulation registered with APVMA. Choose the one that is easiest for you to spread on your skin to ensure complete protection. And always check the instructions on the label.