Is Mosquito Repellent Safe?

Mosquito Repellent Safe - An Apple a Day

When you head away on safari (see above; this is not another South Africa piece, I promise), there are a few things to consider before you touch down – mosquito repellent being one of them.

As we all know I do my best to minimise my exposure to toxic chemicals – from make-up, to plastics, to hair products, even our fresh produce; so it may come as no surprise that before we embarked on our South African adventure, I went searching for some natural alternatives to the old sprays and roll-ons available in the supermarket. What I found, was somewhat concerning.

First things first…


It really depends on who you ask.

DEET or N,N-Diethyl-3-methylbenzamide is the most common, active chemical found in insect repellents and whether or it is considered safe, is fiercely debated. Medical literature discuss the following side effects, however depending on which one you read, some consider them ‘rare’1A, others consider them reason for further investigation:

  • Rashes
  • Skin irritation
  • Large painful blisters
  • Numb or burning lips
  • Nausea
  • Headaches
  • Dizziness
  • Difficulty concentrating
  • Conjunctiva damage
  • Psychosis

In addition, several cases of toxic encephalopathy (seizures) in children exposed to DEET have also been reported2. As such, the use of DEET in young children is not recommended.


Recent research suggests that mosquitos don’t like the smell of Deet so it acts as a deterrent3. However, an article published by BioMed Central4 discusses additional implications of the chemical:

“By using toxicological, biochemical and electrophysiological techniques, we show that deet is not simply a behaviour-modifying chemical but that it also inhibits cholinesterase activity, in both insect and mammalian neuronal preparations. Deet is commonly used in combination with insecticides and we show that Deet has the capacity to strengthen the toxicity of carbamates, a class of insecticides known to block acetylcholinesterase”


To avoid turning into a science nerd, Acetylcholinesterase (AChE) is found in many types of nerve and muscle tissues within the body. The act of blocking AChE can cause “disrupted neurotransmission” and other damaging effects to brain cells. Whilst the studies demonstrate disrupted neurotransmission (i.e. seizures, confusion, agitation, respiratory distress) as a result of Deet in rats, mice and insects, the effects on the human body are less conclusive. Maybe it’s just me, but the seizures in young children exposed to Deet don’t seem so isolated right now, do they?


Here I’ve copied the warnings printed on a bottle of popular mosquito repellent here in Australia:

Do not spray directly on exposed food, water, food preparation areas or food utensils. Do not spray near eyes. Avoid contact with spectacle frames, other plastics, leather and synthetic fabrics. Avoid inhaling spray mist. Will irritate the eyes. Avoid contact with eyes. Wash hands after use. If rash or irritation occurs, discontinue use. WARNING: May be dangerous, particularly to children, if you use large amounts on the skin, clothes or bedding or on large areas of the body, especially if you keep using it for a long time. BEWARE: INTENTIONAL MISUSE BY DELIBERATELY CONCENTRATING AND INHALING CONTENTS CAN BE HARMFUL OR FATAL.


It’s considered effective – 100% DEET was found to offer up to 12 hours of protection while several lower concentration DEET formulations (20%-34%) offered 3–6 hours of protection. Simple as that.


Whilst natural deterrents have been used for centuries, many argue that DEET will trump all natural alternatives on protection time (and they’re right). This is due to the accelerated evaporation rates of such oils, like citronella, that when applied topically, remain a deterrent from anywhere between 30 minutes – 2 hours. That means, re-apply regularly.


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Meet Alyse

I’m a qualified Nutritionist who believes an evidence-based approach to modern nutrition is severely under-rated. Patients are so often left in the dark when it comes to health-care and as a firm believer in the old saying “knowledge is power”, my ultimate goal is to provide my readers, students and patients with clear and actionable advice that ultimately helps you reach your full potential.