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Bug Sprays and Skin Safety: A Dermatologist’s Perspective

Why Use Bug Spray?

Bug sprays help keep insects like mosquitoes, ticks, and flies from biting you. This is important for several reasons including:

• Fewer bites and less scratching, which reduces the risk of skin infections.

• Lower chances of allergic skin reactions like hives or swelling [1].

• Protection from insect or tick-borne diseases that can show up as rashes such as the bull’s-eye rash from Lyme disease or widespread rashes from viruses like Zika or West Nile [3].

• Prevent repeated bites, which can lead to hyperpigmentation or scarring, especially in people with darker skin tones [4].

How Do Bug Sprays Work?

Bug sprays don’t actually kill bugs. Instead, they hide your scent or make your skin unappealing to insects. Many bugs find people by sensing body heat, sweat, or carbon dioxide from breathing. Bug spray ingredients block or confuse these signals, so insects can’t find and bite you as easily [5]. These repellents form a barrier on the skin or clothes, creating a "no-fly zone" that insects avoid. The ingredients in these sprays have different chemical structures but all aim to reduce contact between insects and your skin.

Common Bug Spray Ingredients

There are several active ingredients in bug sprays that have been scientifically proven to work. Each has its own benefits and potential downsides when it comes to how well it works, how long it lasts, and how safe it is for your skin. These repellents are applied to exposed skin or clothing and form a temporary barrier against mosquitoes, ticks, and other biting insects.

DEET

DEET is one of the most well-known and widely used bug spray ingredients. It was developed by the U.S. military in 1946 and has been used safely for decades. DEET works by interfering with insects' ability to detect human scent, effectively “hiding” you from bugs. The strength and duration of protection depend on the concentration–products with 10% DEET can last for about 2 hours, while 30% can provide protection for up to 6 hours, and 50% or more can last up to 12 hours [6]. DEET may reduce the efficacy of sunscreen, especially when applied at the same time. The CDC and EPA recommend applying sunscreen first, allowing it to absorb for about 15 minutes, then applying DEET.

Pros:

• Highly effective against mosquitoes, ticks, fleas, and biting flies

• Long-lasting protection (up to 12 hours with higher concentrations)

• Approved by the CDC and EPA for use, including in children over 2 months [7]

Cons:

• Can feel greasy or sticky on the skin

• Has a strong smell that some people dislike

• May damage plastic, synthetic fabrics, or painted surfaces

• May reduce effectiveness of sunscreen when applied together.

Picaridin

Picaridin is a synthetic compound developed in the 1980s and modeled after a natural compound in black pepper. It works by blocking the insect’s ability to detect human scent, similar to DEET. Picaridin is nearly odorless and doesn’t have the oily feel that DEET sometimes does. In studies, it has shown similar effectiveness to DEET, with protection lasting between 6 and 12 hours depending on the concentration [8].

Pros:

• As effective as DEET, but with a lighter, non-greasy feel

• Odorless or lightly scented

• Safe for children over 6 months

• Doesn’t damage plastic or synthetic materials

Cons:

• May be harder to find in some U.S. stores

• Less well known among consumers

Oil of Lemon Eucalyptus

Oil of Lemon Eucalyptus is a plant-based repellent derived from the lemon eucalyptus tree. Its active ingredient, PMD (para-menthane-3,8-diol), is what provides the bug-repelling power. PMD works similarly to synthetic repellents by interfering with how insects locate human hosts. It can provide protection for up to 6 hours and has been shown to be as effective as low concentrations of DEET in some studies [9].

Pros:

• Plant-derived and considered a more “natural” option

• Comparable effectiveness to 10–15% DEET

• Registered with the EPA and approved for adults and children over 3 years [10]

Cons:

• Not recommended for children under 3 years old

• May cause mild skin irritation in people with sensitive skin

• Shorter protection time than DEET or picaridin

IR3535

IR3535 (Ethyl butylacetylaminopropionate) is a synthetic insect repellent first used in Europe over 30 years ago. It mimics the structure of a natural amino acid, confusing insects and keeping them away. It is often found in combination products that include sunscreen, which makes it a convenient option for outdoor activities. Protection typically lasts up to 8 hours, although it may not be quite as strong against ticks as DEET or picaridin [11].

Pros:

• Gentle on skin and safe for children over 6 months

• Nearly odorless and non-greasy

• Often found in combination products with sunscreen

• Safe for use on clothing and plastics

Cons:

• Slightly less effective than DEET against ticks

• Shorter protection duration compared to higher-strength DEET or picaridin

Natural Essential Oils (e.g., Citronella, Soybean Oil, Peppermint, Lemongrass)

Some people prefer using sprays made with essential oils because they are considered more natural. Common ingredients include citronella, peppermint oil, and soybean oil. These oils can help repel insects by masking the human scent, but their effectiveness is usually limited. Most provide only 30 minutes to 2 hours of protection and require frequent reapplication [12].

Pros:

• May be suitable for very short outdoor exposure (e.g., gardening)

Cons:

• Less effective and short-lasting

• Require frequent reapplication

• Can cause allergic reactions or irritation, especially in sensitive or eczema-prone skin

• Not all are EPA-registered, so effectiveness and safety may vary

Safety Tips for Using Bug Spray

• Always follow the instructions on the product label.

• Don’t apply on broken or irritated skin.

• Avoid spraying near the eyes and mouth; apply to hands first, then rub on the face if needed.

• Use only the amount you need–more isn’t better.

• Wash treated skin after returning indoors.

• Keep sprays out of reach of young children.

Bug sprays are a valuable tool to protect your skin from bites, rashes, and infections. They also help prevent more serious health problems caused by insect-borne illnesses. Each ingredient has pros and cons, and choosing the right one depends on your needs and skin type. Whether you’re hiking through the woods or sitting in your backyard, a good bug spray can help keep your skin healthy and bite-free.

Book a virtual visit with a Tono Health dermatologist today to get a personalized skin care plan that fits your goals and lifestyle.

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References

1. Weir, E. (2002). How to manage insect bites. CMAJ, 167(1), 53. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC117145/

2. Centers for Disease Control and Prevention. Impetigo. https://www.cdc.gov/groupastrep/diseases-public/impetigo.html

3. CDC. Tickborne Diseases of the United States. https://www.cdc.gov/ticks/diseases/index.html

4. Alexis, A. F., & Sergay, A. B. (2020). Acne and post-inflammatory hyperpigmentation in skin of color. Dermatologic Clinics, 38(2), 223-229.

5. Syed, Z. A., & Leal, W. S. (2008). Mosquitoes smell DEET only when they try to bite. PNAS, 105(36), 13598–13603. https://doi.org/10.1073/pnas.0805312105

6. Fradin, M. S., & Day, J. F. (2002). Comparative efficacy of insect repellents against mosquito bites. NEJM, 347(1), 13–18. https://doi.org/10.1056/NEJMoa011699

7. Osimitz, T. G., & Murphy, J. V. (1997). Neurological effects of DEET. Journal of Toxicology: Clinical Toxicology, 35(5), 435–441.

8. EPA. Picaridin. https://www.epa.gov/insect-repellents/picaridin

9. EPA. Oil of Lemon Eucalyptus. https://www.epa.gov/insect-repellents/oil-lemon-eucalyptus

10. Consumer Reports. Best insect repellents of 2023. https://www.consumerreports.org/insect-repellents/best-insect-repellents-a1613222640/

11. EPA. IR3535. https://www.epa.gov/insect-repellents/ir3535

12. Zug, K. A., et al. (2009). Contact allergy to essential oils: patch-test results. Dermatitis, 20(5), 282–289.

This article is for informational purposes only. If you are experiencing a medical emergency, visit an ER or call 911 right away.