Tick repellents deter ticks from attaching to skin or clothing, creating a protective barrier that reduces the risk of tick bites. This is an important public health measure, as it helps prevent the transmission of various tick-borne illnesses such as Lyme disease, Rocky Mountain spotted fever, and Powassan encephalitis.
How Ticks Locate Their Hosts
Ticks locate hosts using various sensory mechanisms. They detect carbon dioxide exhaled by humans and animals from a distance, and sense body heat. Specific body odors and sweat components, such as lactic acid and ammonia, further guide ticks. Beyond chemical and thermal cues, ticks can detect vibrations, including footsteps, and some species perceive changes in light or shadows. Understanding these inputs is fundamental to how repellents disrupt a tick’s ability to find and attach to a host.
The Science Behind Repellent Action
Tick repellents function by interfering with the sensory systems ticks use to find hosts.
DEET (N,N-Diethyl-meta-toluamide) is a widely used spatial repellent. It confuses ticks’ olfactory receptors, making hosts undetectable or unpleasant. DEET interferes with a tick’s ability to detect attractants like lactic acid and carbon dioxide, creating a vapor barrier around the user that prevents ticks from recognizing human scent cues.
Picaridin (KBR 3023 or Icaridin) operates through a similar mechanism, masking human odors and disorienting ticks. This synthetic compound mimics piperine, a natural property found in black pepper plants. Picaridin is odorless, non-greasy, and typically does not damage plastics or synthetic materials, unlike DEET. It blocks insect sensory receptors, making a host less appealing.
Oil of Lemon Eucalyptus (OLE), with its active compound para-menthane-diol (PMD), provides another effective repellent. PMD creates a scent barrier that ticks actively avoid, deterring them through its distinct odor. IR3535 (Ethyl butylacetylaminopropionate) also acts on tick sensory receptors, interfering with their ability to locate hosts. Its mechanism likely involves an intolerance to its odor, disrupting the tick’s detection system.
Repellents deter ticks, while permethrin works as a contact insecticide, killing ticks upon exposure. Permethrin is for clothing and gear, not directly to skin, as skin enzymes quickly deactivate it. Repellents create an invisible shield, whereas permethrin eliminates ticks that come into contact with treated items.
Optimizing Repellent Use
Effective tick repellent use involves proper application and reapplication. The active ingredient’s concentration influences protection duration; higher percentages generally provide longer-lasting effects. For instance, 20-30% DEET is often recommended for effective protection, though concentrations above 50% do not necessarily offer additional time.
Proper application involves covering all exposed skin. Do not spray repellent directly onto the face; instead, spray onto hands and then carefully apply to the face, avoiding eyes and mouth. Applying repellent over clothing, especially on lower extremities like legs and ankles, can also enhance protection. Reapplication is necessary after activities that might reduce its effectiveness, such as heavy sweating or swimming. Always refer to the product label for specific reapplication instructions.
Combining skin repellent with permethrin-treated clothing offers enhanced protection. Permethrin can be applied to boots, clothing, and camping gear, providing a durable barrier that kills ticks upon contact. This dual approach leverages both deterrence and insecticidal action to maximize safety.
Safety Considerations and Proper Use
Using tick repellents safely requires adherence to specific guidelines. Always read and follow product label instructions, which contain important information on application methods and precautions. Apply repellents to exposed skin, avoiding areas with cuts, wounds, or irritation. Apply outdoors for proper ventilation and to prevent chemical inhalation.
When applying repellent to children, an adult should apply it to their own hands first, then rub it onto the child’s skin. Avoid applying repellent to a child’s hands, as they might put them in their mouth. Products containing OLE or PMD should not be used on children younger than three. For infants under two months, use protective clothing instead of repellent. Pregnant or breastfeeding individuals can generally use EPA-registered repellents safely as directed, but consulting a healthcare provider is recommended.
After returning indoors, wash treated skin with soap and water. Store repellent products away from children and pets to prevent accidental exposure. Following these safety measures helps prevent tick-borne illnesses.