Head lice are tiny insects that live on the human scalp, feeding on small amounts of blood. These common pests can cause discomfort and are often a concern for parents and caregivers. While various treatments exist, understanding how temperature extremes affect lice and their eggs, known as nits, can provide effective strategies for managing an infestation. Utilizing high heat or extreme cold can be a practical approach to eradicating these resilient insects from household items.
Lice Vulnerability to Temperature Extremes
Head lice and nits are sensitive to temperatures outside their optimal living conditions on the human scalp. Both excessive heat and severe cold disrupt their biological functions. High temperatures cause proteins to denature and cellular structures to break down, leading to rapid dehydration and death. Conversely, extreme cold can cause ice crystals to form within their cells, damaging tissues and proving lethal.
Effective High Temperatures
High temperatures are an effective method for eliminating head lice and nits from fabrics and household items; exposing them to 130°F (54.4°C) for at least five minutes is sufficient. For practical application, machine washing clothing, bedding, and towels that have been in contact with an infested person in hot water at 130°F or higher is recommended. Drying these items in a hot dryer is often more effective, as lice can sometimes survive washing. A dryer set to a high heat, typically reaching 135°F to 150°F, can kill lice and nits within 20 to 30 minutes. Items like combs and hair clips can be disinfected by soaking them in hot water at least 130°F for 5 to 15 minutes.
Effective Low Temperatures
Extreme cold can also be used to kill head lice and nits, particularly for items that cannot be subjected to high heat. Freezing temperatures work by disrupting the lice’s physiology, although nits have a protective coating that makes them somewhat resilient. To effectively kill lice and nits, items should be placed in a freezer at 5°F (-15°C) or lower for at least 10 hours. Some sources suggest a longer duration, such as 48 hours, for optimal results. This method is suitable for non-washable items like stuffed animals, headphones, or certain hair accessories.
Treating Non-Washable Items and Safety
Treating Non-Washable Items
For items that cannot withstand extreme temperatures, such as delicate stuffed animals or certain hair accessories, alternative methods are available. Sealing these items in a plastic bag for a specified duration can effectively kill lice and nits by depriving them of their human host. Head lice cannot survive off the human body for more than 48 hours without feeding. Therefore, sealing items in a tightly closed plastic bag for at least two weeks ensures any remaining lice starve and nits hatch and die without a food source.
Safety Considerations
Prioritizing human safety is important for temperature-based treatments. Direct application of extreme heat or cold to the scalp or skin is unsafe and should be avoided. For instance, using a blow dryer at high heat close to the scalp is not recommended due to the risk of burns. All cleaning and treatment methods should focus on inanimate objects, and any lice treatment applied to the body should follow product instructions and medical advice.