Why Health Authorities Recommend Icaridin

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Written by: Dr. Hamza A. Khan, MBBS

Abstract

DEET was the first insect-repellent ever developed in the 1940s, and since then, it has dominated the market. However, some of its side effects were quite bothersome for many customers. As a result, it made companies look for alternatives. After searching for the other options for quite some time, the German company Bayer AG ultimately developed a product that came to be known as Icaridin. Developed in the 1980s and commercialized in the late 90s and early 2000s, Icaridin has become the insect repellent of the first choice for many health authorities worldwide. It offers better protection with fewer side effects than DEET and other insect repellents. This article discusses all the properties that make Icaridin unique and an equally effective alternative to DEET and why health organizations trust Icaridin.

Introduction

Vector-borne diseases remain one of the leading causes of death worldwide. Malaria, for example, was responsible for more than half-million deaths in 2020 alone! Although malaria is endemic in Africa, many insect-borne diseases are prevalent in developed countries. For example, Lyme disease transferred by ticks is widespread in the US and Canada. In addition, dengue fever, malaria, and other such disorders are very common in travelers and immigrants from mosquito-ridden countries.

These diseases are life-threatening; however, the good news is they are defeatable. Most vector-borne diseases like malaria and dengue fever have almost been eliminated from the US and many other countries - thanks to the various preventive strategies available today. One such strategy is the use of insect repellents on the skin, either in the form of spray, wipes, or lotion. They provide excellent protection against arthropods for many hours. And, in emergencies, these insect repellents become extremely crucial. 

Some of the most common repellents used are DEET, Icaridin, IR3535, PMD, etc. DEET was the first repellent ever developed by the US army in 1946. However, its drawbacks like greasy feel, unpleasant smell, and other side effects caused by long-term use prompted scientists to find alternatives. As a result, in the 1980s, the German company Bayer AG developed another insect repellent that came to be known as Icaridin - the active ingredient in TotalSTOP.

What Is Icaridin?

Also known as Picaridin, Icaridin is an insect-repelling synthetic chemical that mimics piperidine, a natural repellent found in pepper plants like black pepper. It was first sold under the trade name Bayrepel. It has been sold in Europe and many other countries like Australia since 1998. However, it was registered for use by the EPA in 2001 and became available in the US market in 2005. While Health Canada approved it in 2012.

It is better than DEET in many ways and, as a result, got wide recognition for its efficacy. For example, it is odourless, non-greasy, and does not dissolve plastics like DEET. Plus, it does not cause any skin irritation when used over a long period. Due to these qualities, most public health authorities and organizations recommend Icaridin as the best insect repellent. As a result, it has already taken a significant portion of the insect repellent market and continues to increase its share.

Health Organizations That Recommend Icaridin As The Best Insect Repellent

Icaridin is relatively new not only in the US and Canadian markets, but worldwide. Although developed in the 1980s, it became commercially available in the late 90s and early 2000s. Whereas, DEET was developed in 1946 and was commercialized in 1957. Thus, it has been in use for over six decades, and more than 30% of the US population uses DEET in one or more products. In addition, it gained more trust over the years as there were no compelling alternatives at that time and the natural repellents were very ineffective.

But as time passes, more and more research suggests Icaridin is far better than DEET. It has lesser side effects, more extended protection against insects, and is safe for children or pregnant women.

As a result, many public health authorities and world organizations recommend Icaridin as the substance of choice for insect-borne diseases. Some of them include:

• Since its registration, the EPA (Environmental Protection Agency) has recommended Icaridin as the best insect repellent for people who want an alternative to DEET for its efficacy, safety, and aesthetics.
• According to research by the Environmental Working Group (EWG), one of the largest non-profit organizations for environmental protection, Icaridin has consistently performed as the best bug repellent in today’s market. The organization recommends Icaridin as their top choice over DEET and many other products as it has the same advantages without the same disadvantages like neurotoxicity.
• The WHO has recommended Icaridin as the most reliable product for preventing vector-borne diseases for many years now. As a result, it has become their first-line insect repellent, along with DEET and IR3535, for places where diseases like malaria, are endemic, and travel increases to those areas.
• The CDC (Center For Disease Control) has also promoted Icaridin as an equally effective insect repellent with fewer disadvantages since its registration with the EPA.
• National Health Service (NHS) in the UK and Pest Management Regulatory Agency (PMRA) in Canada consider Icaridin the repellent of the first choice against insects.

Since Icaridin is gaining wide popularity around the globe, more and more research is emerging to support its claims. 

 How Does Icaridin Work?

The exact mechanism of action is unknown; however, Icaridin is believed to work in many ways. There are many theories as to how it works. It is believed that once an Icaridin-containing product, whether spray, wipes, or lotion, is applied to the skin, it forms a thin, invisible layer over it. This layer, in turn, does two things, it repels the insects as well as deters them. 

Icaridin repels insects in the sense that they do not recognize human skin. It seems to block insects from sensing the prey by disrupting their sense of smell. It may also repel insects in other ways. For example, Icaridin may jam the activity of insect antennae. Antennae are the main organs of an insect used to detect smell, taste, touch, air pressure changes, and communication with other insects. Icaridin may also mask volatile chemicals released from the human skin by binding to them and preventing insects from detecting these chemicals.

But even if the insects find human skin and land on it, Icaridin deters them from biting it. Thus, it makes it difficult for the insects to locate the host and prevents them from biting even if they do.  

Icaridin Has a Long Protection Time

Just like other insect repellents, the protection time of Icaridin depends on its concentration. As a result, Icaridin formulations come in different concentrations. However, unlike others, Icaridin-based products are only available in 5% to 20% concentrations. DEET concentration, for example, ranges from 4% to 100%. The first Icaridin-based product in the US had a concentration of 7%. However, these days most of the products contain 20%. 

According to most research on the efficacy of Icaridin, its protection lasts an average of 12 hours. It is equal to or, in some cases, more than the other insect repellents like DEET, have to offer. The high thermal stability and low volatility allow Icaridin to provide more extended protection. According to research published in The Royal Society of Tropical Medicine and Hygiene, Icaridin had a half-life of 4.1 hours, while DEET and IR3535 had 2.9. Half-life is the time by which the amount of a substance is half what was in the beginning. Thus, Icaridin remained on the skin far longer than DEET and IR3535. 

Protection time also depends on the type of insect the human faces. For example, when it comes to mosquitos, Icaridin is far more effective than DEET and other products. According to research published in the European Journal of Tropical Medicine & International Health, compared to DEET, Icaridin was either equal or 1.1 to 2 times more potent against various mosquitoes. Another study conducted in Malaysia also found similar results.

The 12 or 14-hour protection period does not mean the protection is lost suddenly at the end of this time. Instead, as the vapor layer weakens, the insects increasingly begin to sense human skin and bite it. That is why, during research, the time of the first bite, second bite, and so on is very crucial. The time before the first bite is known as the complete protection time (CPT). According to a 2015 research, the median CPT of 20% DEET is 4 to 4.5 hours against the ticks that cause Lyme disease. On the other hand, the median CPT of only 10% Icaridin is 5 to 8 hours. Therefore, 20% Icaridin would be even more protective. Thus, Icaridin is not only more effective against mosquitos but also ticks and other arthropods. 

In Conclusion, Icaridin has a longer duration of safety and provides more robust protection.

Icaridin Offers Optimal Concentration

The concentration of the insect repellent chemical is crucial in determining its efficacy. As the concentration increases, the protection time and the potency of the chemical also increase. As a result, people tend to believe a product with a higher concentration of an active ingredient is more effective. However, this is not the case as, after a specific limit, a further increase in concentration does not lead to better protection. 

The optimal concentration for Icaridin is 20%, while for DEET is 50%. CDC specifically stresses that beyond 50%, DEET does not offer any additional protection. In fact, further increase in DEET concentration leads to side effects as more chemical absorbs into the body and causes neurotoxicity. According to a report by the CDC, between 10% and 20% of the applied DEET is absorbed through the skin. Whereas only 6% of the Icaridin gets absorbed into the human skin. Thus, Icaridin has the edge over the traditional DEET-based repellents.

Icaridin Is Safer To Use Than Other Products

Icaridin is safe to use and is free of the side affects other insect repellents like DEET and IR3535 cause. Research published in many renowned journals like the Journal of American Academy of Dermatology supports the claim that products containing Icaridin like TotalSTOP are less toxic while being equally or more effective than other insect repellents on the market in the following ways:

• Icaridin is approved by the EPA and recommended by CDC, EWG, NHS, WHO, and many more health organizations. 
• It does not cause skin irritation or rash if used for a long time like DEET.
• It also does not cause eye irritation, unlike DEET and IR3535.
• Icaridin does not dissolve plastics or degrade rubber. So if you wear contacts, glasses, or use hiking, camping, climbing gear, or any such thing, you do not need to worry.
• Unlike DEET, there is no incidence of neurotoxicity with Icaridin.
• In some instances, DEET has led to a skin condition called urticaria - red, itchy welts that result from a skin reaction to a trigger. However, Icaridin does not cause urticaria, even in the same individual.
• Only 6% of the applied Icaridin enters the skin, which too gets metabolized, and almost all of it is excreted in urine within a day.
• Icaridin is also safe for babies older than six months and children.
• It is safe to use during pregnancy as well as breastfeeding.

In Conclusion

All these qualities of Icaridin have made it the product of choice for many public health authorities and international organizations. As a result, Icaridin-based products like TotalSTOP are increasingly attracting many customers globally. The trend is also shifting in the US as more people become familiar with Icaridin and its benefits over other products. DEET dominated the market for a long while; however, Icaridin is now finding its way as well.