Head lice are tiny insects that live on the scalp and feed on human blood. An infestation of head lice, while not dangerous, can be extremely irritating. Getting rid of head lice quickly and efficiently is important to provide relief from the itching and prevent spreading lice to others. Many home remedies and over-the-counter products claim to kill head lice instantly, but not all of these treatments are effective or safe.
Can you kill head lice instantly?
It is very difficult to kill head lice instantly at home. Lice are resilient insects that have protective mechanisms to survive on the human scalp. There is no magic instant fix that will immediately kill all head lice.
Most pesticide treatments require leaving the product on for 10 minutes or longer to kill lice. Drowning lice by submerging hair in water can take even longer. Home remedies like mayonnaise and oils work by suffocating lice over time, not instantly.
The closest thing to an instant lice treatment is using a device that desiccates or overheats lice, such as a specialized blow dryer. But even these mechanical treatments take minutes of directed heat or airflow to have an effect.
How to safely get rid of head lice fast at home
While instant results aren’t realistic, you can still kill head lice relatively quickly at home using proven, safe methods. Some of the fastest, most effective home treatments for head lice include:
- Medicated shampoo. Products containing pesticides like pyrethrins or permethrin can kill lice with 10 minutes of contact.
- Wet combing. Using a nit comb on wet, conditioned hair removes lice and eggs.
- Dimethicone lotion. This silicone-based product asphyxiates lice and acts quickly.
- Desiccation devices. Specialized blow dryers and heated air devices rapidly dehydrate lice.
- Prescription medication. Oral ivermectin kills lice by paralyzing their nervous system.
Medicated shampoo
Medicated pediculicidal shampoos contain chemicals that are toxic to lice. Products with pyrethrins or pyrethroids can begin killing live lice within 10 minutes. Permethrin, a synthetic pyrethroid, is one of the most common active ingredients in anti-lice shampoos. While not completely instantaneous, these shampoos offer some of the fastest results outside of a clinic setting.
Wet combing
Wet combing involves applying hair conditioner to saturate locks, then systematically combing sections of hair with a fine-toothed nit comb. The conditioner immobilizes lice and eggs, allowing them to be removed with the comb. While wet combing doesn’t kill lice instantly, it offers a chemical-free way to rapidly remove live lice and nits attached less than 1⁄4 inch from the scalp.
Dimethicone lotion
Dimethicone, a silicone-based product, kills head lice by coating them and interfering with their waxy outer layer that protects them from water loss. This causes the lice to rapidly dehydrate. Applying a dimethicone lotion thoroughly and leaving it on for the recommended time can begin killing lice within minutes through this physical desiccation.
Desiccation devices
There are special devices designed to dry out lice using directed hot air. The LouseBuster and AirAllé devices use one or two handheld bonnet attachments that blow heated air onto sections of hair to desiccate lice. Clinical studies have shown these devices can kill 80-100% of lice in a single 30 minute treatment when used correctly.
Oral medication
Ivermectin is an oral prescription medication sometimes used to treat severe head lice cases. It works by paralyzing and killing lice that ingest blood from a treated person. While not immediate, ivermectin begins working very quickly and can eliminate a lice infestation with a single dose.
Household remedies that don’t kill lice instantly
Many household products are touted online as instant lice killers. However, most of these home remedies take much longer to work than commercial treatments, if they are effective at all.
Mayonnaise
Applying mayonnaise or other oil-based products can begin suffocating head lice after prolonged contact. However, studies show leaving mayonnaise on hair overnight only results in about 15% mortality.
Vinegar
There is no scientific evidence that vinegar kills head lice at all. Vinegar may help loosen nits from hair shafts but does not kill live lice.
Essential oils
Oils like tea tree, eucalyptus, and lavender have limited pediculicidal effects. Leaving these oils on for at least 12 hours is required to kill lice, with less than 50% mortality.
Petroleum jelly
Applying petroleum jelly like Vaseline can begin to smother lice eventually, but leaves hair extremely greasy. This remedy can take over 8 hours to kill lice.
Rubbing alcohol
There is little evidence that rubbing alcohol kills head lice at all. Pure alcohol can dry out lice given extended, repeated contact, but is not a standalone treatment.
How to maximize results from lice treatments
Following some best practices can help improve the efficacy and speed of head lice treatments:
- Carefully follow all instructions for any commercial lice product, including leaving it on for the full recommended time. Do not rinse off early.
- Use a fine-tooth lice comb to remove nits and lice from hair during treatment and after rinsing products out.
- Concentrate on saturating the hair roots rather than length of hair with any liquids or oils.
- Separate hair into sections during treatment to make sure all areas of the scalp are reached.
- Have another person help apply treatments to make sure the back of the head and neck is fully treated.
- Use a hair dryer on a cool setting to help dry wet combing and oil-based treatments more quickly.
- Repeat treatment 9-10 days later to kill newly hatched lice before they can reproduce.
Prescription treatments for severe cases
For severe lice cases that don’t respond to home treatment, prescription options are available:
- Ivermectin – This oral medication paralyzes and kills lice. It has a high success rate with one dose but can require a second.
- Malathion – Malathion lotion kills lice through chemical toxicity. Two treatments a week apart are required.
- Benzyl alcohol – This pediculicide asphyxiates lice and can be used more frequently than other treatments.
- Spinosad – Spinosad quickly paralyzes nerve receptors in lice. It requires two treatments spaced a week apart.
Prescription lice medications are stronger than over-the-counter options and may work when other treatments have failed. Talk to your health care provider if you still have live lice after trying OTC and home remedies.
How to prevent reinfestation after treatment
After completing treatment to get rid of lice, taking steps to prevent a new infestation is key. Recommended prevention measures include:
- Avoid head-to-head contact with anyone who has lice.
- Do not share combs, brushes, hats, helmets, hair ties or other personal headgear items.
- Soak combs and brushes in rubbing alcohol or antibacterial soap after each use.
- Machine wash and dry clothing, bed linens and towels worn or used in the last 2 days using hot water and high heat.
- Items that can’t be washed can be bagged for 2 weeks or ironed using a hot setting.
- Vacuum carpets, furniture, mattresses and car seats thoroughly.
- Retreat hair with a pediculicide if live lice are spotted 10 days after finishing treatment.
Conclusion
While no home remedy can instantly eliminate a head lice infestation, safe and effective treatment options exist that can kill lice relatively quickly. Using pediculicidal rinses, oils or medicines according to package directions, along with manual lice removal and prevention methods, can provide relief from itching and get rid of live lice in several hours to days. Prescription treatments are also available for difficult infestations. With diligence using proper elimination methods and steps to avoid reinfestation, head lice can be effectively treated and controlled without exposing yourself to risky, unproven home remedies.
