I can’t remove lice: what should I do?

Why are lice so hard to get rid of?

Common reasons for treatment failure

Incorrect product application

Persistent lice after several attempts often indicate that the treatment was not applied correctly. Incorrect use of over‑the‑counter or prescription products reduces their efficacy and allows insects to survive.

Typical mistakes include:

Applying too little product, which leaves some lice untreated.
Using the medication on wet hair, which dilutes the formula.
Skipping the recommended contact time, causing premature removal.
Failing to treat the entire scalp and all hair lengths, creating untreated zones.
Ignoring the need for a second application, usually scheduled 7–10 days later.
Using an expired or improperly stored preparation, which may lose potency.

To achieve reliable results, follow these steps:

Read the label and verify the expiration date.
Apply the prescribed amount to dry, detangled hair, ensuring every strand is saturated from scalp to tip.
Cover the hair with a plastic cap or towel if instructed, and keep the product on for the exact duration specified.
After the contact period, rinse thoroughly and use a fine‑toothed nit comb to remove dead lice and eggs.
Perform the repeat treatment on the recommended day, even if no live lice are seen.
Store any remaining product in a cool, dry place, away from direct sunlight.

Complementary actions improve outcomes: wash bedding, clothing, and personal items in hot water; vacuum upholstered furniture; and avoid sharing combs, hats, or towels until the infestation clears. By eliminating the common errors in product application, the likelihood of eradicating lice increases dramatically.

Incomplete removal of nits

Persistent lice problems often stem from incomplete removal of nits. Nits adhere tightly to hair shafts and survive most treatments if not extracted correctly. Their presence guarantees re‑infestation because they hatch within a few days, releasing new lice.

To address residual nits, follow these steps:

Use a fine‑toothed nit comb on damp, conditioned hair. Comb from scalp outward, cleaning the comb after each pass.
Apply a pediculicide that kills lice but not eggs, then repeat the combing process 7–10 days later to catch newly hatched lice before they lay more eggs.
Inspect the entire scalp, focusing on behind ears and the nape of the neck, where nits are most common.
Remove any visible nits manually with tweezers, ensuring the hair strand is held firmly to avoid pulling.
Wash all bedding, clothing, and personal items in hot water (≥ 130 °F) or seal them in a plastic bag for two weeks to prevent hatching.

If nits remain after two treatment cycles, consider professional de‑lousing services or prescription‑strength products. Persistent egg remnants may indicate resistance to over‑the‑counter agents, requiring a different chemical class or a combined approach with manual removal.

Regular monitoring for at least three weeks after treatment confirms success; the absence of live lice and nits during this period indicates complete eradication.

Reinfestation from environment or contacts

Persistent head‑lice problems often result from re‑exposure rather than treatment failure. Infested individuals may regain parasites after contact with contaminated clothing, hats, hairbrushes, or bedding that has not been properly cleaned. Shared spaces such as schools, sports teams, and daycare centers also serve as reservoirs, allowing lice to move from one host to another through close head‑to‑head interaction.

To break the cycle, eliminate viable sources in the surroundings. Wash all clothing, pillowcases, and towels in hot water (minimum 130 °F) and dry on high heat for at least 20 minutes. Seal non‑washable items in a sealed plastic bag for two weeks, a period that exceeds the lice life cycle. Vacuum carpets, upholstered furniture, and car seats, focusing on seams and crevices where nits may hide. Disinfect combs, brushes, and hair accessories by soaking them in hot water for 10 minutes or using an alcohol‑based solution.

Prevent further introductions by enforcing these practices:

Keep personal items separate; avoid borrowing or lending hats, scarves, hair clips, or headphones.
Require children to maintain at least a six‑inch gap between heads during play.
Conduct weekly visual inspections of hair, especially after group activities.
Educate caregivers and staff about the need for immediate treatment of any identified case and for consistent environmental cleaning.

Consistent application of these measures reduces the likelihood that external contacts will re‑seed an infestation, supporting long‑term eradication.

Understanding the lice life cycle

Eggs (nits)

Nits are the tiny, oval‑shaped eggs laid by head‑lice and firmly attached to hair shafts close to the scalp. They appear as white or yellowish specks and can be mistaken for dandruff, but unlike debris they do not detach easily; a gentle tug on the hair will not dislodge them.

Effective removal requires a fine‑toothed nit comb, a steady supply of conditioner, and a systematic approach. The process is:

Apply a generous amount of conditioner to damp hair; this loosens the glue that secures the eggs.
Starting at the scalp, run the nit comb through a small section of hair, pulling the teeth from the scalp outward.
After each pass, wipe the comb on a tissue and repeat the motion until the entire head has been combed at least twice.
Dispose of collected nits by sealing them in a plastic bag or flushing them down the toilet.

Repeated combing over several days is necessary because newly hatched lice will lay fresh eggs. Complement the mechanical method with an approved topical treatment—such as a 1% permethrin lotion or a dimethicone‑based product—applied according to the label’s schedule. These agents kill active insects but do not affect nits, reinforcing the need for diligent combing.

Prevent re‑infestation by washing bedding, hats, and hair accessories in hot water (minimum 130 °F) and vacuuming upholstered furniture. Regularly inspect the hair, especially after contact with others, and repeat the combing routine every 2–3 days for at least two weeks to ensure all eggs have been eliminated.

Nymphs

Nymphs are the immature stage of head‑lice that follows hatching from eggs. They resemble adult lice but are smaller, lighter in color, and lack fully developed reproductive organs. Because they feed on blood, they cause itching and can quickly mature into adults if not eliminated.

Detection of nymphs requires close inspection of the scalp and hair shafts. Use a fine‑toothed comb on wet, conditioned hair; nymphs are visible as tiny, translucent insects moving slowly. Their presence indicates that treatment must target both living insects and newly hatched nymphs.

Effective control measures include:

Applying a pediculicide that remains active for at least 8 hours, covering the entire hair length to reach nymphs hidden near the scalp.
Re‑combining hair 7–10 days after the initial treatment to remove any nymphs that survived the first application.
Washing bedding, hats, and hair accessories in hot water (≥ 130 °F) or sealing them in plastic bags for two weeks to prevent re‑infestation from dormant eggs that could hatch into nymphs.
Avoiding the use of hair products that may coat the scalp and hinder the pediculicide’s contact with nymphs.

Monitoring after treatment should continue for two weeks. If nymphs persist, repeat the chemical application according to the product’s instructions, or consider a non‑chemical option such as a dimethicone‑based lotion that suffocates both nymphs and adults. Consistent removal of nymphs eliminates the breeding pool and halts the cycle of infestation.

Adult lice

Adult lice are the mature stage of the head‑lice life cycle, measuring about 2–3 mm and capable of reproducing quickly. Their presence indicates that earlier treatment has failed to eradicate both the insects and their eggs (nits). Understanding their characteristics is essential for successful removal.

The adult female lays up to eight eggs per day, attaching them firmly to hair shafts near the scalp. Eggs hatch in seven to ten days, producing nymphs that mature into adults within another six to nine days. Consequently, any residual adults can generate a new infestation within two weeks if not eliminated.

Effective steps when adult lice persist include:

Re‑application of a proven pediculicide: Follow the product label for a second treatment 7–10 days after the first application, targeting newly hatched lice that survived the initial dose.
Mechanical removal: Use a fine‑toothed nit comb on wet, conditioned hair. Comb from scalp to tip, rinsing the comb after each pass. Repeat the process daily for at least ten days.
Environmental decontamination: Wash clothing, bedding, and personal items in hot water (≥60 °C) or seal them in airtight containers for two weeks to kill any surviving lice or eggs.
Avoid resistance‑prone products: If the infestation does not improve after two treatment cycles, switch to a different class of insecticide (e.g., dimethicone‑based lotions) or consider a prescription‑only option.

If adult lice remain after these measures, consult a healthcare professional. Prescription treatments, such as oral ivermectin or topical spinosad, may be required, and a clinician can verify proper application and assess for secondary skin irritation.

Preventive practices reduce the likelihood of recurring adult lice:

Limit head‑to‑head contact, especially in crowded settings.
Do not share personal items such as hats, combs, or headphones.
Perform routine scalp inspections after exposure to potential sources.

By addressing adult lice directly with repeated chemical treatment, diligent combing, and thorough environmental control, most persistent infestations can be resolved without further escalation.

What to do if initial treatments fail

Re-evaluate your approach

Confirming a lice infestation

Confirming the presence of head lice requires a systematic visual inspection. Begin by separating the hair from the scalp, using a fine‑toothed comb, preferably a lice detection comb, on a well‑lit surface. Examine each section for live insects, nits, or eggs attached to the hair shaft within a half‑inch of the scalp.

Key indicators to look for:

Live lice: brown or gray bodies, about the size of a sesame seed, moving quickly.
Nits: oval, white or yellowish, firmly glued to the hair shaft; unlike dandruff, they do not flake off.
Scratching or scalp irritation: persistent itching, especially after a night’s sleep, suggests a reaction to bites.
Small, red bumps: evidence of bite sites, often clustered near the neck and behind the ears.

If any of these signs appear, repeat the combing process at least three times over several days to rule out false negatives. Photographing the findings can provide documentation for healthcare providers or school officials. Once an infestation is confirmed, proceed to appropriate treatment protocols and environmental decontamination.

Checking for drug resistance

When lice survive several applications of a standard pediculicide, the possibility of resistance must be evaluated. Resistance occurs when head‑lice populations develop mutations that reduce the efficacy of the active ingredient, rendering typical over‑the‑counter products ineffective.

First, confirm that the treatment was applied according to the manufacturer’s instructions: correct dosage, thorough coverage of hair and scalp, and appropriate waiting time before removal. Incorrect use can mimic resistance and should be ruled out before proceeding.

If proper use is verified, consider the following actions to assess resistance:

Obtain a sample of live lice from the affected individual and send it to a laboratory that performs susceptibility testing. The lab will expose the insects to the product’s active ingredient and report survival rates.
Review recent treatment history. Multiple courses of the same class of pediculicide within a short period increase the likelihood of resistance.
Check for product expiration dates and storage conditions. Degraded formulations may appear ineffective even when resistance is absent.
Compare outcomes of different product classes (e.g., pyrethroids, dimethicone, ivermectin). Success with an alternative class suggests that the original agent is no longer effective.

Based on test results, select a medication from a different chemical class or a physical‑act mode such as silicone‑based lotions that immobilize lice without relying on neurotoxic mechanisms. Follow the new product’s protocol precisely, and repeat the treatment after 7–10 days to eliminate newly hatched nymphs. Continuous monitoring of treatment response will confirm whether resistance has been overcome.

Advanced treatment options

Prescription medications

Prescription medications become necessary when over‑the‑counter products fail to eradicate head lice. A physician can prescribe agents that are not available for self‑sale, providing higher concentrations or alternative mechanisms of action.

Commonly prescribed treatments include:

Malathion 0.5 % lotion – applied to dry hair for eight hours, then washed out; effective against resistant strains.
Benzyl‑alcohol 5 % lotion – kills lice on contact; requires a repeat application after seven days.
Ivermectin 200 µg/kg oral tablets – single dose, with a second dose one week later for confirmed eradication.
Spinosad 0.9 % suspension – applied for ten minutes; does not require a repeat dose.
Permethrin 5 % cream rinse (prescription strength) – higher concentration than OTC version; repeat treatment after seven days.

Prescribing physicians assess factors such as age, allergy history, and severity of infestation before selecting a medication. Dosage instructions must be followed precisely; improper use can reduce efficacy and increase resistance risk. After medication, a fine‑toothed comb should be used to remove dead lice and nits, and household items (bedding, hats, brushes) should be washed in hot water or sealed for two weeks.

If lice persist after a full course of a prescription drug, a second-line agent or combination therapy may be required. Consultation with a healthcare professional ensures appropriate monitoring and prevents unnecessary exposure to toxic substances.

Professional lice removal services

When over‑the‑counter treatments do not eliminate head‑lice, professional removal services become the most reliable option. Trained specialists apply calibrated equipment, such as fine‑toothed combs and FDA‑approved lice‑kill formulations, to eradicate both live insects and their eggs. Their protocols follow evidence‑based guidelines, reducing the risk of recurrence and minimizing chemical exposure.

Key components of a professional service include:

Thorough inspection of the scalp and hair to locate all stages of the parasite.
Application of a controlled, non‑toxic treatment that targets lice and nits simultaneously.
Manual removal of eggs with precision combs, ensuring no residual hatchlings remain.
Post‑treatment counseling on hygiene practices and environmental decontamination.

Choosing a reputable provider requires verification of credentials, such as certification from a recognized health authority, and confirmation that staff undergo regular training. Transparent pricing, clear explanation of the procedure, and a guarantee of follow‑up visits are additional indicators of quality.

After treatment, clients should monitor for any signs of re‑infestation for at least two weeks and follow the specialist’s recommendations on washing personal items and limiting close contact. Prompt re‑evaluation by the same service is typically offered at no extra cost if lice reappear, reinforcing the effectiveness of professional intervention.

Preventing reinfestation

Thorough cleaning of household items

Thorough cleaning of household items is essential when lice persist despite treatment. Lice eggs (nits) can attach to fabric, upholstery, and personal belongings, creating a reservoir for reinfestation. Eliminate this source by following a systematic approach.

Wash all clothing, bedding, and towels in hot water (minimum 130 °F / 54 °C) for at least 10 minutes. If the fabric cannot withstand high temperatures, seal items in a plastic bag for two weeks; the eggs will die without a host.
Dry washed items on the highest dryer setting for 30 minutes. Heat penetrates fibers and kills any surviving lice or nits.
Vacuum carpets, rugs, and upholstered furniture thoroughly. Pay special attention to seams, crevices, and areas where children sit or play. Empty the vacuum canister or bag into a sealed bag and discard it outside the home.
Clean hair accessories (combs, brushes, hats, headbands) by soaking them in hot, soapy water for 10 minutes, then rinsing and drying on high heat or in direct sunlight.
Disinfect hard surfaces (door handles, light switches, countertops) with an EPA‑registered disinfectant. While lice do not survive long on smooth surfaces, regular wiping reduces the chance of accidental transfer.

Repeat the washing and vacuuming cycle after seven days to capture any newly hatched lice that may have been missed initially. Maintaining this routine until no live lice are observed prevents recurrence and supports the overall eradication effort.

Informing close contacts

When head‑lice infestations persist despite treatment, notifying individuals who have had close physical contact is essential to prevent further spread and to coordinate effective eradication.

Inform each contact directly, using a clear and factual message. State that a confirmed infestation remains active, specify the date of the last treatment, and request that they examine themselves or their children within 24 hours. Provide concise instructions for detection, such as checking the scalp and behind the ears for live lice or viable nits within a half‑inch of the hair shaft.

Supply the following information to every contact:

The product or method currently being used and its failure to eliminate the infestation.
Recommended alternative treatments, including over‑the‑counter pediculicides, prescription options, or non‑chemical approaches (e.g., wet combing with a fine‑toothed comb).
A timeline for re‑inspection (typically 7 days after any new treatment) and criteria for confirming clearance.
Guidance on environmental measures: washing bedding, hats, and personal items in hot water, sealing non‑washable items in a sealed bag for two weeks, and avoiding head‑to‑head contact.
Contact details for follow‑up questions or assistance from a healthcare professional.

Document each notification, noting the date, recipient, and method of communication (e.g., text, email, phone call). Retain records for at least two weeks, as this period covers the lice life cycle and allows verification that no new cases emerge.

If a contact reports symptoms or confirms an infestation, arrange synchronized treatment to minimize reinfestation. Encourage all parties to repeat the treatment protocol according to the product’s instructions, typically a second application after 7–10 days, to target newly hatched lice.

By delivering precise, actionable information promptly, you reduce the risk of ongoing transmission and increase the likelihood of complete eradication.

Regular checks for lice and nits

When lice remain after treatment, systematic inspection of the scalp and hair becomes a decisive factor in breaking the infestation cycle.

Inspect the head at least once daily for the first week following treatment, then reduce to every other day for the next two weeks. Continue weekly checks for an additional month to confirm that no new nits have hatched.

Use a fine‑toothed nit comb on dry hair, working from the scalp outward. Separate sections with clips, pull each strand taut, and run the comb slowly to avoid tearing. After each pass, wipe the comb on a white paper towel; any specks of brown or gray indicate viable nits.

Maintain a record of findings to track progress:

Day of inspection
Number of live lice observed
Number of nits detected
Action taken (re‑treatment, manual removal, etc.)

If live lice appear after the initial treatment, repeat the recommended medication according to the product’s schedule and repeat the inspection routine. Consistent monitoring eliminates hidden eggs, prevents re‑infestation, and ensures that the eradication effort succeeds.

When to seek professional medical advice

Persistent infestation despite multiple treatments

Persistent head‑lice infestations after several treatment attempts usually indicate one or more underlying problems. Common causes include incomplete application of the product, resistance of the lice to the active ingredient, re‑infestation from untreated contacts, and failure to eliminate nits that are firmly attached to hair shafts.

To break the cycle, follow a systematic protocol:

Verify that the chosen medication is appropriate for the local lice population; consider a prescription‑strength option or a product with a different mode of action if resistance is suspected.
Apply the treatment exactly as instructed, covering the entire scalp and hair length; leave the product on for the required duration, even if it feels uncomfortable.
After 7–10 days, repeat the application to target newly hatched lice; this second dose is essential for most regimens.
Remove all visible nits using a fine‑toothed comb on wet, conditioned hair; comb every 2–3 days for at least two weeks.
Wash bedding, clothing, and personal items in hot water (≥ 130 °F) or seal them in plastic bags for two weeks to prevent hatching.
Inspect and treat all close contacts—family members, classmates, caregivers—simultaneously to eliminate external sources.

If the infestation persists despite strict adherence to the above steps, seek professional evaluation. A healthcare provider can prescribe oral ivermectin, topical spinosad, or other advanced therapies, and can assess for secondary skin conditions that may complicate treatment. Continuous monitoring and coordination with schools or childcare facilities reduce the risk of recurring outbreaks.

Scalp irritation or infection

Persistent lice infestations often lead to scalp irritation or secondary infection. Recognizing the signs and responding promptly reduces discomfort and prevents complications.

Typical indicators include redness, swelling, tenderness, crusting, or pus formation. Fever, swollen lymph nodes, or a foul odor suggest bacterial involvement that may require medical intervention.

Management steps:

Cleanse the scalp: Apply a gentle, antiseptic shampoo (e.g., chlorhexidine‑based) twice daily for three days. Rinse thoroughly to remove debris and dead lice.
Topical antibiotics: Use over‑the‑counter mupirocin or bacitracin ointment on affected areas after washing. Continue application for five to seven days unless instructed otherwise.
Oral antibiotics: Seek a prescription if inflammation spreads, pus accumulates, or systemic symptoms appear. Common choices include cephalexin or clindamycin, dosage determined by a healthcare professional.
Anti‑itch relief: Apply a low‑dose hydrocortisone cream (1%) to diminish itching. Limit use to 48 hours to avoid skin thinning.
Avoid irritants: Discontinue hair products containing alcohol, fragrance, or harsh chemicals until healing is complete.
Monitor progress: Re‑evaluate the scalp after 48 hours. If irritation persists or worsens, schedule a follow‑up appointment for possible culture and targeted therapy.

Preventive measures remain essential: maintain regular lice combing, wash bedding at 130 °F (54 °C), and limit head‑to‑head contact. Addressing scalp irritation promptly supports successful lice eradication and restores skin integrity.

Allergic reactions to treatments

Allergic reactions to lice‑treatment products can halt progress and worsen discomfort. Recognize the signs—redness, swelling, itching, hives, or breathing difficulty—within minutes to hours after application. Immediate steps include rinsing the affected area with cool water, removing any remaining product, and applying a hypoallergenic soothing agent such as calamine lotion. If respiratory symptoms appear, seek emergency medical care without delay.

When a reaction occurs, discontinue the offending preparation and consult a healthcare professional. The clinician may prescribe a short course of oral antihistamines to control itching and inflammation, and, if necessary, a corticosteroid cream for localized swelling. For severe cases, systemic steroids might be required.

Alternative lice‑control strategies avoid common allergens:

Manual removal with a fine‑toothed comb on wet hair, repeated every 2‑3 days.
Prescription‑grade, non‑pesticidal topical agents such as dimethicone, which coat lice and impede movement without chemical irritants.
Occlusive treatments (e.g., petroleum jelly) applied for several hours to smother lice, followed by thorough combing.

Before selecting any product, verify the ingredient list for known allergens (e.g., pyrethrins, permethrin, lindane, essential oils). Patch testing a small scalp area for 24‑48 hours can identify sensitivity without exposing the entire scalp.

If allergic responses persist despite switching to milder options, a dermatologist may conduct skin‑prick testing to pinpoint specific allergens and recommend long‑term avoidance strategies. Document all reactions and treatments in a personal health record to assist future care providers.

In summary, prompt identification, cessation of the irritant, medical intervention, and selection of hypoallergenic alternatives constitute the essential response to treatment‑induced allergies when lice removal proves difficult.