The 101 on Insect Repellent
With Japanese Encephalitis Virus (JEV) on the increase in Australia, Paediatric Registered Nurse Penny of @sick.happens joins me to review the evidence on Insect Repellents.
why use an insect repellent?
Because insects bite. Not only are these bites annoyingly itchy… they can also cause localized and systemic infections for us. A localized infection means that the site of the bite can be sore, hot to touch and red. More often than not this will resolve on its own, but in some cases the infection will need antibiotics depending on the location and the severity of the reaction to the bite. For some, they can be allergic to insect bites. These bites can also cause an anaphylactic reaction requiring life saving medications.
And- insects can carry infectious diseases. This can cause a systemic infection: aka an infection that spreads within the body. JEV and Dengue Fever are two examples of this. You can read more about Japanese Encephalitis Virus here and here.
Insect repellent can stop these insects from biting in the first place.
what are you looking for in an effective repellent?
Historically, people burned plants and essential oils to repel insects, these contributed to the development of more reliable products.
A registered product
All products that claim to provide protection against mosquitos have to be approved and registered by the Australian Pesticides and Veterinary Medicines Authority (APVMA). There are around 100 products registered - you can search to check that your product is registered at any time.
Method of application
The repellent must be applied to ALL the exposed areas - not just dabs on the skin.
The ingredients
DEET (diethyltoluamide) and Picaridin are the two most common active ingredients used in insect repellents.
DEET comes in varying strengths: from 10-80% of the active ingredient. 10% is ideal for most situations, however it is recommended to use higher DEET concentrations (~ 20%)when in high-risk areas (such as those exposed to malaria, Ross River fever etc). The % refers to how many hours the protection will last. 10% lasts roughly 2 hours.
Picaridin is as effective as DEET, however its effects at repelling insects is not as long lasting.
Extract of lemon eucalyptus are increasingly available on the Australian market. You may have heard this described as p-menthane-3,8-diol, PMD Or oil of lemon eucalyptus. Importantly, this is NOT eucalyptus based essential oil. A higher concentration is required to reach the effectiveness of DEET and picardin.
what about other alternatives?
Wristbands and Stickers - Wristbands and stickers are the least effective compared to typical repellents. This is largely because they don’t protect the entire body. Rather, they provide some protection to the location where the sticker or wristband is.
Electronics - Electronic Mosquito Repellents (the use of high pitched sounds) are not effective at repelling mosquitos. These include plug in repellents and the new and fancy phone-based apps.
Clothing - Some clothing provides some protection (in combination with repellents), check the product is registered.
Things to be mindful of when using insect repellents on children:
Follow manufacturers instructions
Check the labels for instructions on what age group the repellents are safe for (these vary greatly between products - e.g. DEET and picardin are recommended in Australia for 3 months and older, while PMD is recommended for 12months and older)
Be cautious of applying chemical repellents to children that still suck their hands / fingers, as we do not want them to ingest these or rub them into their eyes
Opt for roll on’s rather than sprays for young children as they may not willingly close their eyes or mouth upon application
Adverse reactions to DEET containing repellents are common in kids, but this is generally caused by improper use or accidents
Don’t apply over cuts and abrasions
Don’t neglect other preventative measures such as protective clothing, clearing water around the yard and in high-risk settings, vaccination.
For the pretty version of this blog, visit @j_stokesparish
Common questions:
I make essential oil mixes, don’t they work?
It’s not recommended to DIY repellents- “drops” is not a scientific measurement and there’s a great deal of variability in the final mix. While there are some EO mixes that might work, it’s best to buy registered versions of these as they have to pass quality & safety measures.
What about pre-made essential oil mixes?
There are some essential oil mixes that do work and are registered on the database. The problem with these is that they do not last as long & you end up having to reapply frequently (eg every 30mins). Additionally, higher concentrations are often required for these solutions to have the same effect.
I’ve heard DEET isn’t safe?
The safety of DEET has been extensively studied across the world. These safety measures take into account one off use and daily use, and have resulted in a “safe limit”. Any adverse event related to DEET use has been associated with inappropriate use - for example, ingesting DEET or overapplying. The small amount of risk is outweighed by the risk of disease.
For evidence supporting this blog, you can read the evidence here:
https://www.rch.org.au/kidsinfo/fact_sheets/Insect_repellents_guidelines_for_safe_use/
https://parasitesandvectors.biomedcentral.com/articles/10.1186/1756-3305-7-173
https://theconversation.com/aussies-vs-mozzies-a-users-guide-to-repellents-10964
https://theconversation.com/health-check-do-wrist-bands-work-to-repel-mozzies-50186
https://theconversation.com/what-can-i-eat-to-stop-mosquitoes-biting-me-87178
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011595.pub2/full
https://www.sciencedirect.com/science/article/pii/S0001706X12003452
http://npic.orst.edu/factsheets/DEETgen.html
https://portal.apvma.gov.au/pubcris
https://ww2.health.wa.gov.au/Articles/N_R/Personal-insect-repellents
