What should you do if a person has lice?

«Understanding Head Lice»

«What are Head Lice?»

Head lice (Pediculus humanus capitis) are tiny, wing‑less insects that live on the human scalp and feed on blood. Adults measure 2–4 mm, are gray‑brown, and have six legs with clawed tarsi that enable them to cling to hair shafts. Nymphs, or “lice babies,” hatch from eggs (nits) and reach adult size after three molts over approximately ten days.

The life cycle consists of three stages: egg, nymph, and adult. Females lay up to 10 nits per day, attaching them near the base of hair strands with a cement‑like secretion. Eggs hatch in 7–10 days; nymphs mature after two to three days per molt. An infestation can develop rapidly, with a single female producing hundreds of offspring within a month.

Key identifying features:

Visible nits cemented to hair shafts, often within 1 mm of the scalp.
Live lice moving quickly when the head is examined.
Persistent itching caused by saliva injected during feeding.

Understanding these biological details is essential for selecting effective treatment measures when an infestation is detected.

«How are Head Lice Transmitted?»

Head lice spread primarily through direct head‑to‑head contact. The insects crawl from one scalp to another when hair brushes together, a common occurrence during play, sports, or close personal interaction.

Secondary transmission occurs when individuals share personal items that touch the hair. Items such as combs, brushes, hats, scarves, hair accessories, headphones, pillows, and bedding can harbor live lice or viable eggs. Even brief contact with contaminated fabric can transfer insects.

Fomite transmission, though less frequent, is possible when lice survive on objects for up to 48 hours. Lice do not jump or fly; they move by crawling, limiting spread to situations where hair or objects are in close proximity.

Environmental factors influence risk. Crowded settings, limited personal space, and inadequate hygiene practices increase the likelihood of head‑to‑head contact and sharing of contaminated items.

To reduce transmission:

Avoid head contact with individuals showing signs of infestation.
Do not share combs, hats, or other hair‑contact items.
Wash clothing, bedding, and personal accessories in hot water (≥130 °F) and dry on high heat.
Isolate personal items that cannot be laundered by sealing them in a plastic bag for two days.

Understanding these pathways clarifies preventive measures and informs appropriate response when infestation is identified.

«Symptoms of Head Lice Infestation»

Head lice infestations manifest primarily on the scalp and hair shafts. The most reliable indicator is the presence of live insects or viable eggs (nits) attached to hair strands close to the scalp. Additional signs include:

Intense itching, especially behind the ears and at the nape of the neck, caused by an allergic reaction to bite saliva.
Small, pale‑white or brownish specks (nits) that do not easily brush off; they appear as tiny shells cemented to hair shafts.
Visible adult lice, measuring about 2–3 mm, moving quickly across the scalp.
Red or irritated patches on the scalp, sometimes accompanied by secondary infection from scratching.

Detecting these symptoms enables prompt treatment and prevents further spread.

«Confirmation and Initial Steps»

«How to Confirm a Lice Infestation»

«Visual Inspection»

Visual inspection is the first reliable method for confirming an infestation. Begin by selecting a well‑lit area and a fine‑toothed comb or a magnifying glass. Separate the hair into small sections, starting at the scalp and moving outward. Examine each strand for live insects, which appear as gray‑brown, wingless bodies about the size of a sesame seed, and for nits—tiny, oval, firmly attached eggs resembling dandruff but immobile.

Key points for an effective examination:

Focus on the nape of the neck, behind the ears, and the crown, where lice most often congregate.
Check both hair and scalp skin for signs of irritation or redness.
Use a bright, natural light source or a headlamp to enhance visibility.
Run a fine‑tooth comb through each section; a single pass may miss eggs, so repeat the combing several times.
After combing, place the comb’s teeth on a white surface and inspect for any captured insects or nits.

If live lice or viable nits are identified, proceed with appropriate treatment protocols and preventive measures. If no evidence is found after thorough inspection, consider alternative diagnoses before initiating chemical remedies.

«Using a Fine-Toothed Comb»

A fine‑toothed comb is essential for removing lice and nits after a confirmed infestation. The device works by mechanically separating the parasite from the hair shaft, allowing visual confirmation of removal and reducing reliance on chemical treatments.

First, dampen the hair with water and a conditioner to soften strands and prevent breakage. Apply the conditioner liberally, then comb from the scalp outward, pulling the comb through each section in slow, deliberate strokes. After each pass, wipe the teeth on a clean tissue or rinse the comb in warm water to clear captured insects.

Repeat the process on all affected areas, typically every 2–3 days for two weeks, to interrupt the lice life cycle. Dispose of collected lice and nits by flushing them down the toilet or sealing them in a plastic bag before discarding. Clean the comb after each use with hot, soapy water, followed by a rinse in boiling water for at least five minutes to ensure sterility.

Key points for effective combing:

Use a comb with teeth spaced 0.2–0.3 mm apart.
Work on small sections (2–3 cm) to maintain thoroughness.
Perform combing on a well‑lit surface to spot remaining lice.
Combine with regular laundering of clothing and bedding at ≥60 °C.

When executed correctly, fine‑toothed combing eliminates live lice and most nits, providing a reliable, non‑chemical method for managing an infestation.

«Notifying Others»

When lice are detected, informing relevant parties prevents further spread and enables coordinated treatment.

Identify the individuals who need to be told. Typically include:

The person’s close contacts (family members, roommates, classmates).
The institution responsible for the environment where exposure occurred (school, daycare, workplace).
A healthcare professional if medical advice or prescription medication is required.

Communicate promptly and clearly. Use a direct message that states the diagnosis, outlines recommended actions (e.g., checking hair, applying treatment, washing bedding), and provides a timeline for re‑evaluation. Preserve privacy by limiting details to essential facts and using confidential channels such as sealed letters, secure emails, or private phone calls. Follow up with reminders and confirm that each party has taken the necessary steps.

«Treatment Options»

«Over-the-Counter Treatments»

«Pyrethrin-Based Treatments»

When an infestation of head lice is identified, pyrethrin‑based products are often the first option recommended because they act quickly on the nervous system of the insects. Pyrethrins are natural extracts from chrysanthemum flowers, combined with piperonyl‑butoxide to enhance penetration through the insect cuticle. The formulation kills live lice within minutes and disrupts egg development, though some nits may survive and require a second application.

Key considerations for effective use:

Apply the product to dry hair, ensuring complete coverage from scalp to tips.
Follow the manufacturer’s timing instructions, typically leaving the lotion or shampoo on for 10 minutes before rinsing.
Repeat the treatment after 7–10 days to eliminate newly hatched lice that were protected during the first application.
Comb the hair with a fine‑toothed lice comb after each treatment to remove dead insects and residual nits.
Avoid contact with eyes, broken skin, or mucous membranes; wash hands thoroughly after application.

Safety profile: Pyrethrin products are approved for children over 2 months and adults, but they may cause mild irritation, itching, or temporary redness. Individuals with a history of asthma or allergic reactions to chrysanthemum should be monitored closely or consider alternative therapies.

Resistance issues: Repeated use in some regions has led to reduced susceptibility of lice populations. If treatment fails after two cycles, switch to a prescription‑only option such as a spinosad or ivermectin preparation, and verify proper application technique.

In practice, combine pyrethrin treatment with environmental measures—wash bedding and clothing in hot water, vacuum upholstered furniture, and avoid sharing personal items—to prevent re‑infestation.

«Permethrin-Based Treatments»

Permethrin, a synthetic pyrethroid, is the most widely used topical agent for lice eradication. Over‑the‑counter preparations contain 1 % permethrin in a lotion or cream rinse, approved for individuals two months of age and older.

Application steps:

Wash hair with regular shampoo and towel‑dry.
Apply the full‑strength product to damp hair, covering the scalp and all hair shafts.
Leave the preparation on for the time specified on the label (typically 10 minutes).
Rinse thoroughly with warm water; do not use conditioner.
Comb wet hair with a fine‑toothed lice comb to remove dead insects and nits.
Repeat the entire process after 7–10 days to eliminate any newly hatched lice.

Safety considerations:

Permethrin is generally well tolerated; mild skin irritation may occur.
Use with caution on infants under two months, on pregnant or nursing individuals, and on people with known hypersensitivity to pyrethroids.
Do not apply to broken or inflamed skin.

Resistance monitoring:

Document treatment failure; if lice persist after two correct applications, consider alternative agents such as ivermectin or dimethicone, as resistance to permethrin has been reported in some regions.

Environmental control:

Wash bedding, clothing, and towels used within 48 hours at 130 °F (54 °C) or seal them in a plastic bag for two weeks.
Vacuum carpets, upholstery, and car seats to remove stray nits.
Avoid sharing personal items such as combs, hats, and hair accessories during the treatment period.

«Prescription Medications»

«Ivermectin Lotion»

Ivermectin lotion is a topical pediculicide approved for treating head‑lice infestations. It belongs to the macrocyclic lactone class and works by disrupting nerve transmission in the parasite, leading to rapid paralysis and death.

Application procedure:

Apply a measured amount of lotion to dry, unwashed hair, ensuring coverage from scalp to tips.
Massage gently to distribute evenly; avoid contact with eyes and mucous membranes.
Leave the product on the scalp for the time specified in the product label, usually 10 minutes.
Rinse thoroughly with water; do not use shampoo immediately after treatment.
Repeat the application after seven days to eliminate any newly hatched lice.

Safety considerations:

Contraindicated in individuals with known hypersensitivity to ivermectin or any formulation component.
Not recommended for children under 12 kg unless a physician authorizes off‑label use.
Common adverse effects include mild scalp irritation, itching, or erythema; severe reactions are rare.
Pregnant or breastfeeding persons should consult a health professional before use.

Clinical data report cure rates above 90 % when the regimen is followed precisely, outperforming many traditional neurotoxic insecticides that face rising resistance. Ivermectin’s distinct mechanism reduces the likelihood of cross‑resistance, making it a reliable alternative when standard treatments fail.

Effective eradication also requires mechanical removal of nits with a fine‑tooth comb and regular laundering of clothing, bedding, and personal items at temperatures of at least 50 °C. Combining these measures with ivermectin lotion maximizes the probability of complete elimination and prevents reinfestation.

«Malathion Lotion»

Malathion lotion is a prescription‑strength pediculicide that contains 0.5 % malathion, an organophosphate insecticide effective against head‑lice infestations, including strains resistant to pyrethrins. The formulation is applied to dry hair, left for eight hours, then rinsed thoroughly; a second application after seven days eliminates newly hatched nymphs.

Key considerations when using Malathion lotion:

Verify that the patient is at least six months old; infants younger than this age are not candidates.
Confirm the absence of scalp wounds, dermatitis, or known hypersensitivity to organophosphates.
Avoid use on chemically treated hair (e.g., bleach, dye) because absorption may increase.
Do not combine with other lice‑killing products; simultaneous use can cause toxic interactions.
Pregnant or nursing individuals should discuss risks with a healthcare professional before treatment.

Safety information:

Mild irritation, itching, or a transient burning sensation may occur; these effects usually resolve without intervention.
Systemic toxicity is rare but possible if the product is ingested, applied to broken skin, or used excessively.
Store the lotion at room temperature, away from heat and direct sunlight; keep out of reach of children.

When Malathion lotion is selected as part of a lice‑management plan, follow the prescribed regimen, perform thorough combing with a fine‑toothed nit comb after each application, and launder bedding, clothing, and personal items in hot water to prevent reinfestation.

«Non-Chemical Approaches»

«Wet Combing Method»

The wet‑combing technique removes live lice and nits without chemicals. It requires a fine‑toothed comb, a tub of water, and a conditioner or detangling spray.

Begin by washing the scalp with regular shampoo, then apply a generous amount of conditioner. The conditioner loosens the egg shell, allowing the comb to glide through the hair. Keep the hair wet throughout the process; reapply conditioner as needed to maintain slip.

Divide the hair into sections no wider than one inch. Starting at the scalp, drag the comb down to the ends in a slow, steady motion. After each pass, wipe the comb on a white tissue or rinse it in the water to inspect captured material. Continue combing each section until no live insects or eggs appear on the comb.

Repeat the entire procedure every three to four days for two weeks. This schedule corresponds to the lice life cycle and prevents newly hatched nits from maturing.

After the final session, wash all clothing, bedding, and personal items in hot water (minimum 130 °F) or place them in a sealed plastic bag for two weeks. Vacuum carpets and upholstered furniture to eliminate stray insects.

The wet‑combing method offers a non‑toxic, cost‑effective solution when an infestation is detected. Regular execution according to the outlined schedule ensures complete eradication.

«Suffocating Agents (e.g., Petroleum Jelly, Mayonnaise)»

Suffocating agents create an airtight barrier over the scalp, preventing lice from breathing and forcing them to detach. Petroleum jelly and mayonnaise are common household options because they adhere well to hair and skin.

Apply a generous layer of petroleum jelly from the hairline to the tips of each strand.
Cover the head with a shower cap to maintain occlusion.
Leave the treatment on for 8–12 hours, preferably overnight.
Remove the product with a fine-tooth comb, then wash hair with mild shampoo.

Mayonnaise works similarly:

Warm mayonnaise to body temperature to increase spreadability.
Coat the entire scalp and hair, ensuring coverage of the nape and behind the ears.
Secure a plastic cap for 6–8 hours.
Comb out lice and nits, then rinse thoroughly.

Effectiveness depends on complete coverage and sufficient exposure time. Inadequate application leaves gaps where lice survive. Both substances may cause temporary greasiness; thorough washing eliminates residue.

Precautions include testing a small skin area for allergic reaction, avoiding use on infants under two months, and not applying to broken skin. Suffocating agents complement mechanical removal but should not replace regular combing and environmental cleaning.

«Environmental Cleaning and Prevention»

«Cleaning Personal Items»

«Laundering Clothes and Bedding»

Treat all clothing, towels, and bedding that have contacted the infested individual as potentially contaminated. Immediately place each item in a sealed plastic bag to prevent lice from escaping while preparing for laundering.

Use water temperature of at least 130 °F (54 °C) for washing. Hot water kills both lice and their eggs.
Add a full dose of laundry detergent. Detergent reduces surface tension, allowing heat to penetrate more effectively.
After washing, tumble‑dry on high heat for a minimum of 20 minutes. Dryer temperature above 130 °F eliminates any surviving nits.
For items that cannot be machine‑washed, seal in a plastic bag for two weeks. Lice cannot survive without a host for more than 48 hours; the extended period guarantees death.
Ironing or steaming non‑washable fabrics at temperatures above 150 °F (65 °C) provides an additional lethal exposure.
Discard or disinfect vacuum bags, brushes, and any cleaning tools used on the affected area. Soak them in hot water or run them through a dryer on high heat.

All cleaned items should be stored in clean, sealed containers until the infestation is fully resolved. This protocol removes the primary reservoir of lice, preventing re‑infestation after treatment.

«Cleaning Hairbrushes and Combs»

When an infestation is confirmed, every tool that contacts hair must be sterilized to prevent reinfestation. Hairbrushes and combs harbor viable nits and adult insects, making thorough decontamination a critical step in the eradication process.

Remove visible debris by rinsing the device under hot running water.
Submerge the brush or comb in a solution of 1 part household bleach to 9 parts water for at least 10 minutes. Alternative disinfectants such as 70 % isopropyl alcohol or a commercial lice‑killing spray are acceptable if bleach is unavailable.
Scrub the bristles or teeth with a stiff brush to dislodge any remaining particles.
Rinse thoroughly with hot water to eliminate chemical residues.
Allow the item to air‑dry on a clean surface; heat accelerates the killing of any surviving parasites.

If the equipment is made of plastic or metal, the same procedure applies. For wooden or delicate brushes, replace the disinfectant with a 0.5 % hydrogen peroxide solution and limit soak time to 5 minutes to avoid material damage.

Discard any brush or comb that shows signs of wear, broken teeth, or cannot withstand the cleaning process, as compromised tools may retain viable lice stages despite treatment. Replacing these items eliminates a potential source of recurrence.

«Cleaning the Home Environment»

«Vacuuming»

When lice are present, eliminating the insects from the surrounding environment reduces the chance of re‑infestation. Vacuuming removes live lice, nits, and shed hairs that may harbor eggs, thereby breaking the life cycle outside the host’s body.

Vacuuming targets the areas most likely to contain detached parasites. The process must be thorough and repeated to capture newly hatched insects that emerge after the initial sweep.

Use a vacuum equipped with a high‑efficiency filter (HEPA or equivalent).
Run the machine over carpets, rugs, and floor mats for at least two minutes per square meter.
Clean upholstered furniture, including cushions, armrests, and backs.
Treat mattresses, box springs, and bedding by vacuuming every surface, then fold and vacuum the edges of the mattress.
Vacuum curtains, drapes, and any fabric that contacts the head or shoulders.

After each session, seal the vacuum bag or empty the canister into a disposable bag, close it tightly, and discard it in an outdoor trash container. Clean or replace the filter according to the manufacturer’s instructions. Repeat the entire procedure every 2–3 days for two weeks, as nits may hatch during this period. This systematic approach diminishes the environmental reservoir of lice and supports overall eradication efforts.

«Sealing Non-Washable Items»

When a person is infested with lice, any clothing, accessories, or personal items that cannot be laundered must be isolated to prevent re‑infestation. Lice lose viability after 24–48 hours without a host; sealing creates an environment that exceeds this survival window.

Identify every non‑washable article that has contacted the affected individual—silk scarves, delicate hats, costume jewelry, upholstered cushions, or plush toys. Place each item in a resealable plastic bag or airtight container. Remove excess air, seal tightly, and label with the date of containment. Store the sealed packages in a cool, dry location for at least 14 days; this period guarantees that any remaining lice or nits will die.

After the isolation period, open each bag in a clean area. Inspect the contents for live insects; if none are detected, the items may be returned to regular use. If live lice are observed, repeat the sealing process or consider professional disposal.

Additional precautions include keeping sealed items away from untreated clothing, washing hands after handling bags, and avoiding direct contact with the infested person until treatment is complete. These steps minimize the risk that non‑washable belongings become a source of recurrence.

«Preventative Measures»

«Avoiding Head-to-Head Contact»

Avoiding direct contact between heads is a primary measure for interrupting the spread of lice. The insects move primarily by crawling from one hair shaft to another, so any situation that brings scalps together creates an immediate transfer pathway.

Practical actions:

Keep children and adults apart during play, sports, or close‑range activities that involve leaning heads together.
Encourage the use of individual seating arrangements in classrooms, buses, and other shared spaces; place chairs at least an arm’s length apart.
Discourage activities that involve resting heads on shared surfaces such as pillows, helmets, or caps without a protective barrier.
In group settings, schedule breaks that allow participants to step away from each other, reducing prolonged proximity.

Additional precautions:

Do not share hats, scarves, hair accessories, or headphones. Assign personal items to each individual.
Wash and dry any shared fabric items on high heat if they must be reused.
Monitor environments for inadvertent head‑to‑head contact and intervene promptly when it occurs.

By maintaining physical separation of heads and limiting shared objects, the likelihood of lice transmission drops dramatically, supporting effective containment and treatment efforts.

«Regular Checks»

Regular monitoring after an initial treatment is essential for confirming that the infestation has been eliminated and for catching any new hatchlings before they spread. Conduct examinations at least once a week for three weeks, then reduce to bi‑weekly for another month. Use a fine‑toothed comb on damp, conditioned hair, working from the scalp outward. Examine the comb after each pass; nits appear as tiny, oval, brownish specks attached to the shaft, while live lice are larger, grayish insects that move quickly.

Key actions during each check:

Separate hair into manageable sections.
Run the comb slowly, ensuring the teeth reach the scalp.
Wipe the comb on a white surface to improve visibility.
Record any findings and note the location of detected insects.
If live lice or nits are found, repeat treatment immediately and continue weekly checks for another two weeks.

Parents, caregivers, and affected individuals should perform the checks themselves or enlist a trained professional. Maintaining a consistent schedule reduces the risk of a secondary outbreak and supports a swift return to normal activities.

«When to Seek Professional Help»

«Persistent Infestations»

Persistent lice infestations indicate that initial treatment failed to eliminate all parasites or their eggs. Common reasons include inadequate application of medication, resistance to commonly used pediculicides, re‑infestation from untreated contacts, and surviving nits hidden in dense hair. Identifying the underlying cause is essential before proceeding with additional measures.

To break the cycle, follow a systematic approach:

Verify that the product was used exactly as directed, including recommended exposure time and repeat dosing schedule.
Inspect the scalp and hair with a fine‑toothed comb under bright light to locate remaining live lice or viable nits.
Remove all detectable nits manually; each nits’ removal reduces future hatch rates.
Treat all close contacts—family members, classmates, caregivers—with the same regimen or an alternative approved medication.
Wash clothing, bedding, and personal items in hot water (≥130 °F/54 °C) or seal them in airtight containers for two weeks to prevent resurgence.
Consider a prescription‑strength agent (e.g., ivermectin, malathion) if resistance to over‑the‑counter products is suspected; obtain it under medical supervision.

Monitor the situation for at least two weeks after the final treatment. Conduct weekly comb checks; any detection of live lice warrants immediate retreatment. Document the timeline of interventions to provide clear information for healthcare providers if professional assistance becomes necessary.

«Allergic Reactions or Scalp Irritation»

Lice treatments often contain chemicals that may trigger allergic responses or irritate the scalp. Redness, swelling, itching, or a burning sensation after applying a pediculicide signals a reaction that requires prompt attention.

Typical indicators include:

Localized rash or hives on the treated area
Excessive tearing or watery eyes
Swelling that extends beyond the hairline
Persistent pain or throbbing that does not subside within an hour

If any of these symptoms appear, follow these steps:

Rinse the scalp thoroughly with lukewarm water to remove residual product.
Apply a gentle, fragrance‑free moisturizer or a pediatric‑safe soothing gel to alleviate irritation.
Administer an oral antihistamine (e.g., diphenhydramine) according to the package dosage, unless contraindicated.
Document the reaction and the product used for future reference.

Seek medical evaluation when:

Symptoms intensify after the initial rinse
Breathing difficulties, wheezing, or facial swelling develop
The reaction persists beyond 24 hours despite self‑care measures
The individual has a known history of severe allergic responses

Healthcare providers may prescribe a corticosteroid cream, adjust the treatment regimen, or recommend an alternative non‑chemical approach such as manual removal. Recording the incident helps prevent repeat exposure and ensures safer management of future infestations.

«Infants and Young Children»

When lice are discovered on an infant or young child, immediate action protects the child’s health and prevents spread to others.

First, confirm the infestation by examining the scalp and hair for live insects or nits attached close to the scalp. Use a fine-toothed comb under bright light; move the comb slowly to avoid missing hidden nits.

Next, treat the child with an approved pediculicide. Choose a product specifically labeled for use on infants or toddlers, following the manufacturer’s dosage and application instructions precisely. After the recommended contact time, rinse thoroughly with lukewarm water.

After treatment, remove remaining nits manually. Comb the hair in sections, starting at the scalp and working toward the ends. Dispose of each combed-out nits in sealed plastic bags to eliminate re‑infestation.

Implement environmental controls:

Wash all bedding, clothing, and towels used by the child in hot water (≥130 °F) and dry on high heat.
Vacuum carpets, upholstered furniture, and car seats; discard vacuum bags or clean canisters immediately.
Seal non‑washable items (e.g., stuffed animals) in a sealed bag for two weeks, the typical lifespan of a louse away from a host.

Monitor the child daily for two weeks. If live lice reappear or irritation persists, repeat treatment according to the product’s guidelines or consult a pediatric healthcare professional for alternative therapy.

Educate caregivers on preventive measures: avoid head-to-head contact with other children, discourage sharing of hats, hair accessories, or bedding, and conduct regular scalp checks during outbreaks. These steps minimize the risk of future infestations in infants and young children.