Which products are the most effective at repelling mosquitoes and preventing dengue fever? Here’s what you should know about each. Make sure you do your part to prevent mosquito breeding, as well.
Pharmacists in Singapore recommend products containing Deet (diethyltoluamide), a chemical compound with a proven safety track record, which has been used for decades. It is highly effective against mosquitoes and also biting flies, fleas and ticks.
A newer compound, Picaridin, has been found to be as effective as Deet in protecting against mosquitoes.
Generally, when these are used as directed, they have proven to be safe and effective, even for pregnant and breastfeeding women.
Deet has been shown to be safe in the second and third trimester of pregnancy. However, during the first trimester, it should be sprayed onto the clothing instead of the skin to minimise absorption.
But, as with any product, there is a possibility of developing side effects when using mosquito repellent.
Side effects, including skin redness, rashes or a slight burning sensation, are usually temporary and will go away once you stop using the product.
You should avoid using products which contain ingredients you are allergic to. Inhalation of Deet and other repellents in large amounts can cause throat and bronchial (airway) irritation, as well as coughing.
To minimise these side effects, do not spray the insect repellent directly onto your face. Spray onto your hands first before applying it to your face.
Repellents should not be used on babies younger than two months old. Instead, cover the crib, stroller and baby carrier with mosquito netting.
For kids, avoid applying repellents to their hands as it is likely to make contact with their eyes or mouths.
The choice of mosquito repellent depends on the duration of time spent outdoors.
A higher concentration of repellent will have longer-lasting effectiveness. An insect repellent with 7 per cent Deet lasts about two hours, while one with 15 per cent Deet may last up to four hours.
(Also read: 6 dengue myths and facts every parent should know)
Citronella and other oils
They repel mosquitoes by masking body chemicals. They include plant-based oils such as lemon eucalyptus, cedar, peppermint and lemongrass.
These are not as effective as Deet-containing repellents. Such products may also irritate the skin.
Mosquito patches and wristbands
These are scented with citronella or similar oils, which helps to prevent mosquitoes from smelling humans.
It’s unclear how long such patches last, or how many patches a person needs. Different brands also come in different strengths.
(Also read: Mosquito bites on babies: How to treat and prevent)
Carbon dioxide traps
These attract and kill mosquitoes. People generally emit more carbon dioxide than a small trap, and mosquitoes may still be drawn towards them instead.
These emit repellents when burnt. They can be a fire hazard and can produce the same amount of PM2.5 pollutants as burning 75 to 137 cigarettes.
The smoke emitted may aggravate asthma conditions and trigger wheezing.
(Also read: 7 plants that repel mosquitoes naturally)
Ultrasonic mosquito repellents
These repel mosquitoes by emitting a high-pitched sound that humans cannot hear. At least 10 field studies have shown that these do not have any discernible effect.
A version of this article first appeared in The Straits Times.