Insect
Repellent Use and Safety
See
also the Downloadable
Mosquito Repellent Fact Sheet.
Q.
Is DEET safe?
A. Yes, products containing DEET are very safe when used according
to the directions. The regulation of substances such as DEET is
determined by the U.S.
Environmental Protection Agency (EPA). Because DEET is so widely
used, a great deal of testing has been done. When manufacturers
seek registration with the EPA, laboratory testing regarding both
short-term and long-term health effects must be carried out. Over
the long history of DEET use, very few confirmed incidents of toxic
reactions to DEET have occurred when the product is used properly.
To read more information about DEET safety see the National Pesticide
Information Center [NPIC], EPA re-registration eligibility decision
fact sheet (npic.orst.edu/factsheets/DEETgen.pdf)
and the EPA
Re-registration eligibility decision (R.E.D.) fact sheet.
Q.
Why should I use insect repellent?
A. Insect repellents help people reduce their
exposure to mosquito bites that may carry potentially serious
viruses such as West Nile virus, and allow them to continue to
play and work outdoors.
Q.
When should I use mosquito repellent?
A. Apply repellent when you are going to
be outdoors and will be at risk for getting bitten by mosquitoes.
Q.
What time of day should I wear mosquito repellent?
A. Many of the mosquitoes that carry the
West Nile virus are especially likely to bite around dusk and
dawn. If you are outdoors around these times of the day, it is
important to apply repellent. In many parts of the country, there
are mosquitoes that also bite during the day, and these mosquitoes
have also been found to carry the West Nile virus. The safest
decision is to apply repellent whenever you are outdoors.
Q.
How often should repellent be reapplied?
A. Follow the directions on the product you
are using in order to determine how frequently you need to reapply
repellent. Sweating, perspiration or getting wet may mean that
you need to re-apply repellent more frequently. If you are not
being bitten, it is not necessary to re-apply repellent. Repellents
containing a higher concentration of active ingredient (such as
DEET) provide longer-lasting protection.
Q.
Should I wear repellent while I am indoors?
A. Probably not. If mosquitoes are biting
you while you are indoors, there are probably better ways to prevent
these bites instead of wearing repellent all the time. Check window
and door screens for holes that may be allowing mosquitoes inside.
If your house or apartment does not have screens, a quick solution
may be to staple or tack screening (available from a hardware
store) across the windows. In some areas community programs can
help older citizens or others who need assistance.
Q.
How does mosquito repellent work?
A. Female mosquitoes bite people and animals
because they need the protein found in blood to help develop their
eggs. Mosquitoes are attracted to people by skin odors and carbon
dioxide from breath. Many repellents contain a chemical, N,N-diethyl-m-toluamide
(DEET), which repels the mosquito, making the person unattractive
for feeding. DEET does not kill mosquitoes; it just makes them
unable to locate us. Repellents are effective only at short distances
from the treated surface, so you may still see mosquitoes flying
nearby. As long as you are not getting bitten, there is no reason
to apply more DEET.
Q.
Which mosquito repellent works the best?
A. The most effective repellents contain
DEET (N,N-diethyl-m-toluamide), which is an ingredient used to
repel pests like mosquitoes and ticks. DEET has been tested against
a variety of biting insects and has been shown to be very effective.
The more DEET a repellent contains the longer time it can protect
you from mosquito bites. A higher percentage of DEET in a repellent
does not mean that your protection is better—just that it
will last longer. DEET concentrations higher than 50% do not increase
the length of protection.
Q.
How does the percentage of DEET in a product relate to the amount
of protection it gives?
A. Based on a 2002 study:
-
A product containing 23.8% DEET provided an average of 5 hours
of protection from mosquito bites.
- A
product containing 20% DEET provided almost 4 hours of protection
-
A product with 6.65% DEET provided almost 2 hours of protection
-
Products with 4.75% DEET and 2% soybean oil were both able to
provide roughly 1 and a half hour of protection.
Choose
a repellent that provides protection for the amount of time that
you will be outdoors. A higher percentage of DEET should be used
if you will be outdoors for several hours while a lower percentage
of DEET can be used if time outdoors will be limited. You can
also re-apply a product if you are outdoors for a longer time
than expected and start to be bitten by mosquitoes. (For more
information, see Table 1: Fradin and Day, 2002. See Publications
page.)
Q.
Why does CDC recommend using DEET?
A. DEET is the most effective and best-studied
insect repellent available. (Fradin, 1998). Studies using humans
and mosquitoes report that among
those tested only products containing DEET offer
long-lasting protection after a single application. (Fradin and
Day, 2002. See Publications
page.)
Q.
Are non-DEET repellents effective (e.g. Skin-So-Soft, plant-based
repellents)?
A. Some non-DEET repellent products which
are intended to be applied directly to skin also provide some
protection from mosquito bites. However, studies have suggested
that other products do not offer the same level of protection,
or that protection does not last as long as products containing
DEET. A soybean-oil-based product has been shown to provide protection
for a period of time similar to a product with a low concentration
of DEET (4.75%) (Fradin and Day, 2002. See Publications
page.).
People
should choose a repellent that they will be likely to use consistently
and that will provide sufficient protection for the amount of
time that they will be spending outdoors. Product labels often
indicate the length of time that protection that can be expected
from a product. Persons who are concerned about using DEET may
wish to consult their health care provider for advice. The National
Pesticide Information Center (NPIC) can also provide information
through a toll-free number, 1-800-858-7378 or npic.orst.edu.
Q.
I'm confused. Which products contain "DEET"?
A. Most insect repellents that are available
in stores are now labeled with the word "DEET" as well as labeled
with the chemical name. Look for N,N-diethyl-m-toluamide or, sometimes,
N,N-diethyl-3-methylbenzamide. Choose a repellent that offers
appropriate protection for the amount of time you will be outdoors
(see above). A higher percentage of DEET should be used if you
will be outdoors for several hours while a lower percentage of
DEET can be used if time outdoors will be limited.
Using
Repellents Safely
Q.
What are some general considerations to remember in order to use
products containing DEET safely?
A. Always follow the recommendations appearing on the product
label.
- Use
enough repellent to cover exposed skin or clothing. Don't apply
repellent to skin that is under clothing. Heavy application
is not necessary to achieve protection.
- Do
not apply repellent to cuts, wounds, or irritated skin.
- After
returning indoors, wash treated skin with soap and water.
- Do
not spray aerosol or pump products in enclosed areas.
- Do
not apply aerosol or pump products directly to your face. Spray
your hands and then rub them carefully over the face, avoiding
eyes and mouth.
Q.
How should products containing DEET be used on children?
A. No definitive studies exist in the scientific literature
about what concentration of DEET is safe for children. No serious
illness has been linked to the use of DEET in children when used
according the product recommendations. The American
Academy of Pediatrics (AAP) Committee on Environmental Health
has recently updated their recommendation for use of DEET products
on children, citing: "Insect repellents containing DEET (N,N-diethyl-m-toluamide,
also known as N,N-diethyl-3-methylbenzamide) with a concentration
of 10% appear to be as safe as products with a concentration of
30% when used according to the directions on the product labels."
The AAP and other experts suggest that it is acceptable to apply
repellent with low concentrations of DEET to infants over 2 months
old. Other guidelines cite that it is acceptable to use repellents
containing DEET on children over 2 years of age.
Repellent
products that do not contain DEET are not likely to offer the
same degree of protection from mosquito bites as products containing
DEET. Non-DEET repellents have not necessarily been as thoroughly
studied as DEET, and may not be safer for use on children.
Parents
should choose the type and concentration of repellent to be used
by taking into account the amount of time that a child will be
outdoors, exposure to mosquitoes, and the risk of mosquito-transmitted
disease in the area. Persons who are concerned about using DEET
or other products on children may wish to consult their health
care provider for advice. The National Pesticide Information Center
(NPIC) can also provide information through a toll-free number,
1-800-858-7378 or npic.orst.edu.
Always
follow the recommendations appearing on the product label when
using repellent.
- When
using repellent on a child, apply it to your own hands and then
rub them on your child. Avoid children's eyes and mouth and
use it sparingly around their ears.
- Do
not apply repellent to children's hands. (Children may tend
to put their hands in their mouths.)
- Do
not allow young children to apply insect repellent to themselves;
have an adult do it for them. Keep repellents out of reach of
children.
- Do
not apply repellent to skin under clothing. If repellent is
applied to clothing, wash treated clothing before wearing again.
Using
repellents on the skin is not the only way to avoid mosquito bites.
Children and adults can wear clothing with long pants and long
sleeves while outdoors. DEET or other repellents such as permethrin
can also be applied to clothing (don’t use permethrin on
skin), as mosquitoes may bite through thin fabric. Mosquito netting
can be used over infant carriers. Finally, it may be possible
to reduce the number of mosquitoes in the area by getting rid
of containers with standing water that provide breeding places
for the mosquitoes.
Q.
Is DEET safe for pregnant or nursing women?
A. There are no reported adverse events following
use of repellents containing DEET in pregnant or breastfeeding
women.
Q.
Are there any risks due to using repellents containing DEET?
A. Use of these products may cause skin reactions
in rare cases. If you suspect a reaction to this product, discontinue
use, wash the treated skin, and call your local poison control
center. There is a new national number to reach a Poison Control
Center near you: 1-800-222-1222.
If
you go to a doctor, take the product with you. Cases of serious
reactions to products containing DEET have often been related
to occasions where the product was not used as directed, such
as swallowing, using over broken skin, or using for multiple days
without washing skin in between use, for example. Always follow
the instructions on the product label.
Insect
Repellents and Sunscreen
Q.
Can I use an insect repellent containing DEET and a product containing
sunscreen at the same time?
A. Yes. People can and should use both sunscreen and DEET
when they are outdoors to protect their health. Follow the instructions
on the package for proper application of each product. Apply sunscreen
first, followed by repellent containing DEET.
To protect from sun exposure and insect bites, you can also wear
long sleeves and long pants. You can also apply insect repellent
containing DEET or permethrin to your clothing, rather than directly
to your skin.
Q.
Has CDC changed its recommendations for use of DEET and sunscreen?
A. No. Based on available research, CDC believes it is safe
to use both products at the same time. Follow the instructions
on the package for proper application of each product. Apply sunscreen
first, then insect repellent containing DEET, to be sure that
each product works as specified.
Q.
Should I use a combination sunscreen/DEET-based insect repellent?
A. Because the instructions for safe use of DEET and safe
use of sunscreen are different, CDC does not recommend using products
that combine DEET with sunscreen.
In most situations, DEET does not need to be reapplied as frequently
as sunscreen. DEET is safe when applied correctly. The rare adverse
reactions to DEET have generally occurred in situations where
people do not follow the product instructions. Sunscreen often
requires frequent reapplication, so using a combined product is
not recommended. You do not need to reapply insect repellent every
time you reapply sunscreen. Follow the instructions on the package
for each product to get the best results.
Q.
I heard about a study saying that there may be some type of interaction
between repellents containing DEET and sunscreen. Is this true?
A. There has been attention to a study concerning the chemicals
in DEET and sunscreen presented at a scientific meeting. This
is an in vitro study, which means that it is a laboratory study
that did not include human or animal testing. The goal of the
study was to examine absorption of these chemicals, and it did
not evaluate or make conclusions about health effects related
to this issue. The study authors stated that further evaluation
of the interaction of these chemicals should be conducted. The
study has not yet been published (as of July 2003).
Evaluation
by the EPA, which regulates products such as DEET, indicates that
it is safe to use insect repellents containing DEET and sunscreen
at the same time. CDC recommends using two separate products because
sunscreen requires frequent applications while DEET should be
used sparingly. Follow the directions on the package for each
product, and consult your physician or pharmacist if you have
questions. CDC's recommendations for the safe use of insect repellents
on children and adults remain unchanged.
More
information
Q.
Where can I get more information about repellents?
A. For more information about using repellents
safely, please consult the Environmental
Protection Agency (EPA) Web site or consult the National Pesticide
Information Center (NPIC), which is cooperatively sponsored by
Oregon State University and the U.S. EPA. NPIC can be reached
at: npic.orst.edu
or 1-800-858-7378.
Additional
Information:
Home
West Nile Virus and Dead Birds
West Nile Virus, Pregnancy and Breast-Feeding
West Nile Virus Is A Risk You Can Do Something
About With A Few Simple Steps.
Cases of West Nile Human Disease
West Nile Virus and Dogs and Cats
West Nile Virus: Information and Guidance
for Clinicians
Insect Repellent Use and Safety
Symptoms of West Nile Virus
Testing and Treating West Nile
Virus in Humans
Blood Transfusion, Organ Donation and
Blood Donation Screening Information
Transmission of the West Nile Virus
