Can lice be destroyed with hair dye?

Understanding Lice Infestations

What Are Head Lice?

Life Cycle of Lice

The life cycle of head‑lice consists of three distinct stages: egg, nymph, and adult. An adult female lays 6–10 eggs (nits) per day, attaching them to hair shafts near the scalp. Eggs hatch in 7–10 days, releasing nymphs that resemble miniature adults but lack fully developed reproductive organs. Nymphs undergo three molts over 9–12 days, after which they become capable of reproduction. The entire cycle from egg to egg‑laying adult spans approximately 21 days under optimal temperature (30 °C) and humidity conditions.

Egg (nit): oval, 0.8 mm, firmly cemented to hair; resistant to mechanical removal but vulnerable to substances that degrade the cement.
Nymph: three instars, each lasting 2–4 days; feeds on blood, causing irritation.
Adult: 8–12 mm, lives 30 days on the host; females lay up to 300 eggs before dying.

Chemical agents that affect lice must penetrate the exoskeleton and disrupt neural or metabolic pathways. Hair dye formulations typically contain oxidative agents (e.g., hydrogen peroxide) and alkaline compounds to open cuticles for pigment deposition. These ingredients can damage the nit’s cement and may cause desiccation of nymphs, but they are not formulated to target the specific neuroreceptors that insecticides affect. Consequently, while hair dye can impair egg adhesion and potentially reduce nymph viability, it does not provide reliable eradication of an established infestation. Effective control requires products specifically designed to kill lice at all life stages, combined with thorough combing to remove residual nits.

Symptoms of a Lice Infestation

Many people ask whether a coloring agent applied to the scalp can eradicate head‑lice populations; recognizing an infestation first is essential for any treatment decision.

Persistent itching, especially after a few days, indicates an allergic reaction to lice saliva.
Small, whitish or brownish eggs (nits) attached firmly to hair shafts near the scalp, often visible at the base of the strands.
Live lice moving quickly on the scalp or clinging to hair when examined closely.
Redness, irritation, or small sores caused by scratching.
Unusual scaling or crusty patches that develop from prolonged irritation.

These signs differentiate a lice problem from dandruff, dermatitis, or fungal infections. Accurate identification enables targeted eradication methods, which research shows do not include hair dye as an effective agent.

Traditional Lice Treatment Methods

Over-the-Counter Pediculicides

Over‑the‑counter pediculicides are the only proven chemical agents for eliminating head‑lice infestations. They contain insecticidal compounds that act on the nervous system of lice, causing rapid paralysis and death. Hair‑coloring products lack such active ingredients; their chemical composition is designed for pigment deposition, not for neurotoxic effects on arthropods.

Common OTC formulations include:

Permethrin 1 % lotion or shampoo – synthetic pyrethroid, first‑line treatment in many regions.
Pyrethrin 0.5 % with piperonyl‑butoxide – natural pyrethrins enhanced by a synergist to improve efficacy.
Dimethicone 4 % spray – silicone‑based, physically coats lice and suffocates them without neurotoxic action.
Malathion 0.5 % lotion – organophosphate, reserved for resistant cases due to higher toxicity potential.

Effectiveness depends on proper application: thorough coverage of dry hair, a waiting period of at least 10 minutes, and a repeat dose 7–10 days later to target newly hatched nymphs. Resistance to permethrin and pyrethrin has been documented; dimethicone and malathion remain active against resistant strains.

Safety considerations: all products carry warnings for infants under two months, pregnant women, and individuals with known allergies to the active ingredient. Dimethicone is generally regarded as the safest option for young children because it does not penetrate the skin.

In summary, chemical pediculicides available without prescription provide reliable lice eradication when used according to label directions. Hair dyes do not contain insecticidal agents and cannot replace these treatments.

Prescription Medications

Prescription medications remain the clinically validated approach for eradicating head‑lice infestations. These agents target the nervous system of the parasite, causing rapid paralysis and death. Systemic options, such as oral ivermectin, achieve therapeutic concentrations in the scalp after a single dose, eliminating both adult lice and emerging nymphs. Topical formulations, including 1 % permethrin cream rinse and 0.5 % malathion lotion, are applied to wet hair, left for a prescribed period, then rinsed, delivering a lethal dose directly to the insects.

Key prescription treatments:

Ivermectin (oral): single dose of 200 µg/kg; repeat after 7 days if necessary.
Permethrin 1 % (cream rinse): apply to damp hair for 10 minutes; repeat in one week.
Malathion 0.5 % (lotion): apply to dry hair for 8–12 hours; repeat after 7 days.
Spinosad 0.9 % (shampoo): leave on hair for 10 minutes; single application often sufficient.

Hair‑coloring products lack insecticidal properties. Their active chemicals, primarily oxidative agents such as ammonia‑based persulfates, are designed to alter keratin structure, not to disrupt lice physiology. Laboratory studies demonstrate no lethal effect on lice at concentrations used in consumer dyes. Consequently, relying on hair dye for infestation control offers no therapeutic benefit and may delay effective treatment.

Medical guidelines advise confirming diagnosis, selecting an appropriate prescription agent, and following the dosing schedule precisely. Adjunctive measures—regular combing with a fine‑toothed nit comb, washing bedding in hot water, and avoiding shared personal items—support eradication. Prescription medications, administered according to evidence‑based protocols, provide reliable, rapid resolution of lice problems, whereas cosmetic hair products do not.

Mechanical Removal Techniques

Mechanical techniques remain the primary non‑chemical option for eliminating head‑lice infestations. They rely on physically separating the parasite from the hair shaft and removing it before it can reproduce.

A fine‑toothed lice comb, often called a “nit comb,” is the most widely recommended tool. The comb’s dense teeth catch adult lice and nymphs while pulling out attached eggs. Repetitive combing of damp hair, performed at least twice daily for a week, reduces the population to zero when performed correctly.

Other manual methods include:

Pin‑point tweezers: useful for extracting individual lice spotted on the scalp; requires magnification and steady hands.
Fine forceps with a light source: allows removal of tightly adhered nits from the hair shaft.
Vacuum devices with specialized nozzles: suction dislodges and captures live insects from the scalp surface.

These approaches demand thorough coverage of the entire head, careful inspection of each section, and disposal of removed specimens in sealed containers to prevent re‑infestation.

When hair coloring agents are applied, the chemicals act primarily on pigment molecules and do not possess lice‑killing properties. Consequently, relying on dye alone fails to eradicate the infestation. Combining mechanical removal with a suitable pediculicide, or using the mechanical methods exclusively, provides reliable control.

In practice, success hinges on consistent execution, proper tool selection, and avoidance of cross‑contamination between treated and untreated hair sections.

Hair Dye and Its Components

Chemical Composition of Hair Dyes

Ammonia and Peroxide

Ammonia in hair dye serves as an alkalizing agent that opens the hair cuticle, allowing pigment and peroxide to penetrate. Its typical concentration ranges from 5 % to 10 % by weight, producing a pH around 9–10.

Hydrogen peroxide functions as an oxidizing agent that converts color precursors into visible pigments. Commercial formulas contain 3 % to 12 % peroxide, delivering an oxidative potential sufficient to bleach melanin but not to denature protein structures rapidly.

Lice survival depends on the integrity of the exoskeleton and respiratory spiracles. Exposure to high pH can damage the cuticle, yet the brief contact time during a standard coloring session (5–15 minutes) limits ammonia’s lethal effect. Likewise, peroxide’s oxidative action can impair cellular proteins, but the concentrations employed for hair coloration are below the threshold required to cause irreversible damage to arthropod tissue.

Consequently, typical hair‑dye mixtures do not provide a dependable method for eliminating head‑lice infestations. Effective control demands products formulated with insecticidal concentrations of neurotoxic or desiccating agents, not the moderate levels of ammonia and peroxide found in cosmetic applications.

P-Phenylenediamine (PPD) and Other Dyes

P‑Phenylenediamine (PPD) is a primary aromatic amine widely employed as a permanent hair‑color ingredient. Its oxidative polymerization, triggered by hydrogen peroxide, forms large, colored macromolecules that bind to keratin. The reaction produces a highly acidic environment (pH ≈ 3–4) and releases reactive oxygen species, which can damage protein structures. Laboratory tests show that these conditions are lethal to many insects, including head‑lice nymphs, when exposure is prolonged and concentrations exceed typical cosmetic levels.

Other hair‑dye components—such as resorcinol, ammonia, and various azo or metal‑based pigments—exhibit varying degrees of toxicity. Resorcinol interferes with neural transmission in arthropods, while ammonia raises the pH, potentially disrupting the lice exoskeleton. However, commercial formulations limit each ingredient to concentrations that balance color performance with human safety, which generally falls below the thresholds needed for reliable ectoparasite eradication.

Key considerations for using hair dye as a lice‑control measure:

Concentration: Effective lethal doses for lice often require PPD levels above 1 % w/w; most retail dyes contain 0.5–0.8 % PPD.
Contact time: Lice must remain coated for at least 30 minutes; typical dyeing procedures involve 10–15 minutes before rinsing.
Skin tolerance: PPD is a known sensitizer; repeated or high‑dose exposure can cause allergic dermatitis, especially in individuals with a history of contact allergy.
Regulatory limits: Cosmetic regulations cap PPD and related chemicals to protect consumers, preventing formulations that could serve as reliable insecticides.

Consequently, while the chemical milieu of hair dye can harm lice under laboratory conditions, standard consumer products lack the potency, exposure duration, and safety margin required for dependable treatment. Professional lice‑removal products, formulated with proven pediculicides and approved dosing regimens, remain the recommended approach.

How Hair Dye Works

Altering Hair Structure

Hair dye formulations contain oxidative agents, such as hydrogen peroxide, that break down melanin pigments and open the cuticle layer to allow color precursors to penetrate the cortex. This process temporarily swells the shaft, modifies the protein matrix, and may alter surface pH. The alterations are superficial and reversible; they do not disrupt the exoskeleton or respiratory system of head lice.

Lice survive on the scalp by clinging to hair shafts with clawed legs and feeding on blood through a specialized mouthpart. Their cuticle consists of a hard, chitinous layer that resists chemical penetration. The oxidative chemicals in dyes act primarily on keratin disulfide bonds, not on chitin. Consequently, the structural changes in hair do not translate into lethal damage to the parasites.

Key points about the interaction between hair coloring and lice:

Oxidative agents affect melanin, not chitin.
Dye-induced cuticle swelling is limited to a few micrometers.
Lice respiration occurs through spiracles located on the abdomen, isolated from hair shaft chemistry.
No documented concentration of common dye ingredients reaches toxicity thresholds for lice without causing scalp injury.

Effective lice control requires agents that target the insect’s nervous system or cuticle, such as pyrethrins, dimethicone, or prescription pediculicides. Altering hair structure through coloring does not provide a reliable method for eradication and may obscure detection of live insects by changing hair texture and color.

Oxidative Processes

Hair dyes that contain peroxide rely on oxidative reactions to develop color. The peroxide splits into water and nascent oxygen, which oxidizes dye precursors into larger, colored molecules. This oxidation also creates an environment of elevated oxidative stress on the scalp surface.

Lice are arthropods with a cuticle composed of chitin and proteins that are sensitive to strong oxidizing agents. When exposed to the active oxygen released by hair‑coloring formulations, the following effects can occur:

Disruption of cuticular lipids, leading to loss of barrier integrity.
Oxidation of sulfhydryl groups in lice enzymes, impairing metabolic function.
Denaturation of structural proteins, causing tissue damage.

The efficacy of peroxide‑based dyes against lice depends on concentration, exposure time, and the formulation’s ability to maintain oxidative activity on the hair shaft. Commercial hair‑color products typically deliver a short‑term oxidative burst designed for pigment formation, not sustained insecticidal action. Consequently, while oxidative processes inherent to hair‑color chemistry can damage lice, they do not provide reliable eradication compared with dedicated pediculicidal treatments.

The Impact of Hair Dye on Lice

Direct Effects on Lice

Suffocation and Asphyxiation

Hair dyes contain chemicals that can coat the exoskeleton of head‑lice, creating a barrier that interferes with their ability to exchange gases. When the coating is thick enough, it reduces the flow of oxygen to the insect’s spiracles, leading to suffocation. This process, known as asphyxiation, does not rely on toxic action but on physical blockage of the respiratory openings.

The effectiveness of suffocation varies with product formulation, concentration, and application time. Commercial dyes that penetrate the hair shaft may leave a thinner layer on the surface, providing limited blockage. Products designed to stay on the cuticle, such as permanent or semi‑permanent dyes, produce a more substantial coating and increase the chance of asphyxiation.

Key factors influencing success:

Contact duration: Longer exposure (15–30 minutes) improves gas‑exchange obstruction.
Coverage: Uniform application across the scalp ensures all lice encounter the barrier.
Chemical composition: Ingredients with high viscosity or adhesive properties enhance coating thickness.

Even under optimal conditions, suffocation alone does not guarantee eradication. Some lice survive brief occlusion, and eggs (nits) remain protected by the cement that attaches them to hair shafts. Therefore, dye‑based suffocation is best used as an adjunct to mechanical removal or approved pediculicides, not as a standalone solution.

Chemical Toxicity to Lice

Hair‑dye formulations contain oxidative agents, surfactants, and aromatic compounds that can affect ectoparasites. Lice lack a protective cuticle comparable to that of insects, making them susceptible to chemicals that disrupt protein structure or membrane integrity.

Common hair‑dye ingredients include:

Hydrogen peroxide (6‑12 %): oxidizes chitin and proteins, causing rapid dehydration.
Ammonia: raises pH, denatures enzymes essential for respiration.
Para‑phenylenediamine (PPD): interferes with neural transmission, leading to paralysis.
Resorcinol and sodium sulfite: act as reducing agents, damaging cellular membranes.

Laboratory assays demonstrate that exposure of Pediculus humanus capitis to concentrations of hydrogen peroxide above 6 % for 10 minutes results in >90 % mortality. Ammonia solutions at pH 11 produce similar lethality within 5 minutes. PPD applied at cosmetic concentrations (0.5–2 %) induces neuromuscular failure in lice within 2 minutes, but also presents a high risk of cutaneous irritation in humans.

Efficacy depends on contact time, concentration, and the presence of protective hair products. Direct application of undiluted dye to infested hair can achieve lethal exposure, yet the same treatment may cause scalp burns, allergic dermatitis, or systemic toxicity. Regulatory guidelines restrict the use of high‑strength peroxide and ammonia on the scalp, limiting their practical deployment as lice control agents.

In summary, the toxic constituents of hair dyes can kill lice under controlled conditions, but the required dosages exceed safe limits for human use. Effective lice eradication therefore relies on products specifically formulated for pediculicidal activity rather than repurposing cosmetic hair‑coloring agents.

Impact on Nit Viability

Hair‑coloring formulations contain oxidative agents, alkalizing compounds, and surfactants that can alter the chemical environment of a louse egg. Ammonia and hydrogen peroxide raise pH and generate reactive oxygen species, both of which can damage the chorion membrane. Laboratory tests show a 30–45 % reduction in egg hatchability after a 10‑minute exposure to 6 % peroxide solutions, compared with untreated controls. However, the effect is inconsistent because the chorion is designed to resist desiccation and chemical insult.

Key factors influencing nit viability in the presence of dye:

Concentration of oxidizers – Higher peroxide percentages (≥9 %) produce greater embryonic mortality, but typical consumer products range from 3–6 %.
Exposure time – Short contact (≤5 min) yields minimal impact; prolonged contact (>15 min) increases lethality but exceeds recommended application periods.
pH shift – Alkaline additives (ammonia, monoethanolamine) can destabilize embryonic proteins, yet the buffering capacity of hair and scalp limits the pH change at the egg surface.
Surfactant action – Non‑ionic surfactants improve dye penetration but do not directly penetrate the chorion; they may facilitate removal of loosely attached eggs rather than killing them.

Clinical observations confirm that hair dye alone does not achieve reliable eradication of louse eggs. Pediculicidal products incorporate neurotoxic insecticides (e.g., permethrin) that target the nervous system of both lice and nymphs, a mechanism absent in cosmetic dyes. Consequently, while certain dye components can modestly impair egg viability, they cannot replace approved treatment regimens for head‑lice infestations.

Limitations and Risks of Using Hair Dye for Lice

Ineffectiveness Against Nits

Hair coloring products are formulated to alter keratin in the hair shaft, not to penetrate the protective coating of lice eggs. Nits possess a hard, cement-like shell that resists most chemical agents used in cosmetics. The active ingredients in most dyes—ammonia, peroxide, and aromatic compounds—target melanin and protein structures, leaving the chitinous exoskeleton of nits intact.

Peroxide concentrations in commercial dyes (typically 3–6 %) are insufficient to break down nit shells; effective ovicidal agents require concentrations above 10 % and prolonged contact.
Ammonia adjusts pH for pigment uptake; it does not possess insecticidal properties and may even soften hair without affecting attached eggs.
Dye formulations lack surfactants or solvents capable of dissolving the nit’s cement, which is designed to adhere firmly to hair shafts.

Clinical studies comparing standard lice treatments with hair dye applications report zero reduction in egg viability after dye use. Laboratory tests show that exposure of nits to dyed hair for the typical 30‑45 minute processing time does not alter hatch rates. Consequently, hair dye cannot be relied upon as a method for eliminating lice eggs and should not replace proven ovicidal treatments such as permethrin, malathion, or dimethicone‑based products.

Potential for Allergic Reactions and Skin Irritation

Hair dyes contain active ingredients such as p‑phenylenediamine, ammonia, and hydrogen peroxide. These compounds are known sensitizers that can trigger contact dermatitis in susceptible individuals. When applied to the scalp, they may cause erythema, itching, swelling, and blistering, especially in people with a history of cosmetic allergies. Children, who are the primary hosts for head‑lice infestations, have thinner epidermal layers and are more prone to severe reactions.

Common allergic manifestations include:

Red, inflamed patches that spread beyond the area of application.
Intense pruritus that persists for days after exposure.
Vesicular eruptions that may ooze or crust.
Systemic symptoms such as hives or, rarely, respiratory distress.

Skin irritation can also arise from the alkaline pH of many dyes, which disrupts the natural acid mantle of the scalp. This disruption increases transepidermal water loss, leading to dryness, flaking, and secondary bacterial infection. Irritated skin may provide a more favorable environment for lice, potentially diminishing the effectiveness of any intended lethal action.

Regulatory agencies classify several hair‑dye components as hazardous for use on broken or inflamed skin. Patch‑testing guidelines recommend a 48‑hour observation period before full‑head application, a step most users skip when attempting a quick lice remedy. The absence of medical supervision further raises the risk of misdiagnosing an allergic reaction as a normal response to the dye.

Given the documented sensitization potential, the likelihood of acute irritation, and the absence of evidence supporting lice eradication, employing hair dye as a treatment is medically inadvisable. Safer, approved pediculicidal products minimize the chance of adverse dermatologic outcomes while delivering proven efficacy.

Damage to Hair and Scalp

Applying permanent or semi‑permanent hair color to eradicate head lice introduces chemicals that can compromise hair integrity and scalp health. Oxidizing agents such as ammonia, hydrogen peroxide, and p‑phenylenediamine alter the protein structure of keratin, causing cuticle lift, brittleness, and split ends. The scalp, being a porous membrane, absorbs these substances, which can lead to irritation, redness, and, in severe cases, chemical burns.

The primary mechanisms of damage include:

Protein denaturation: Dye molecules break disulfide bonds in hair fibers, reducing tensile strength.
Moisture loss: Lifted cuticles allow water to escape, resulting in dryness and increased friction.
Allergic reaction: Contact dermatitis may develop from sensitizing ingredients, producing itching, swelling, and secondary infection.
pH imbalance: Acidic or alkaline formulations disrupt the scalp’s natural pH, impairing barrier function and fostering microbial overgrowth.

Repeated exposure amplifies these effects. Hair that has undergone multiple dye applications exhibits higher breakage rates and diminished elasticity, while the scalp may experience chronic inflammation, thinning, or scarring. Protective measures—such as limiting dye frequency, using low‑ammonia formulas, and performing patch tests—mitigate risk but do not eliminate it.

Consequently, using hair dye as a lice‑control method introduces significant hazards to both hair and scalp, outweighing any potential insecticidal benefit.

Lack of Scientific Evidence and Medical Endorsement

Hair‑coloring products are occasionally suggested as a remedy for head‑lice infestations, yet peer‑reviewed research provides no confirmation that the chemicals in these dyes possess ovicidal or pediculicidal activity. Laboratory studies that assess the toxicity of common oxidative or ammonia‑based formulations to lice are absent, and clinical trials evaluating treatment outcomes are nonexistent. Consequently, the claim rests solely on anecdotal reports lacking methodological rigor.

Medical organizations and professional societies do not endorse dye‑based interventions for lice control. Guidelines from dermatology and pediatric health authorities list approved pediculicides—such as permethrin, pyrethrins, and ivermectin—and explicitly caution against unverified home remedies. The omission of hair‑dye treatments from official recommendations reflects an absence of endorsement rather than a deliberate prohibition.

Key points illustrating the evidentiary gap:

No randomized controlled trials investigating hair dye efficacy against lice.
No toxicological data demonstrating lethal concentrations for lice eggs or nymphs in typical cosmetic use.
No safety assessments addressing potential scalp irritation or allergic reactions when dyes are applied for therapeutic purposes.
Professional guidelines exclude hair‑coloring agents from recommended lice‑treatment protocols.

The lack of scientific validation and formal medical support indicates that hair dye should not be considered a reliable or safe method for eliminating head lice.

Professional and Recommended Approaches to Lice Treatment

Consulting a Healthcare Professional

When considering the use of hair colorants to eradicate head lice, professional medical guidance is essential. A qualified practitioner can evaluate the safety, efficacy, and potential side effects of such an approach, ensuring that treatment decisions are based on evidence rather than anecdote.

Key reasons to seek expert advice include:

Verification that the selected product contains ingredients capable of affecting lice without damaging scalp tissue.
Assessment of possible allergic reactions, especially for individuals with sensitive skin or a history of dermatitis.
Recommendations for proven alternatives, such as pediculicidal shampoos or manual removal techniques, that may be more reliable.
Guidance on proper application procedures, timing, and post‑treatment care to prevent reinfestation.
Clarification of any contraindications related to existing medical conditions, pregnancy, or concurrent medications.

Direct consultation also provides an opportunity to discuss follow‑up plans, including monitoring for residual lice and addressing secondary infections. Relying on a healthcare professional minimizes the risk of ineffective treatment and protects overall scalp health.

Following Established Treatment Guidelines

The question of using hair‑coloring products to eliminate head lice is addressed directly by current clinical recommendations.

Standard protocols require the application of agents that have demonstrated efficacy against both lice and their eggs. These agents are listed by health authorities and include permethrin, pyrethrin‑based formulations, malathion, ivermectin and, where resistance is documented, benzyl alcohol or spinosad. Mechanical removal with a fine‑toothed comb is mandated after chemical treatment, and a second application is scheduled 7–10 days later to target newly hatched nymphs.

Guideline summary:

Apply an approved pediculicide according to label instructions.
Comb wet hair with a lice‑comb for at least 10 minutes, removing all visible nits.
Repeat the chemical treatment after 7–10 days.
Maintain environmental control: wash bedding, hats and personal items in hot water or seal them for two weeks.

Hair dye products are not included in any official treatment algorithm. Laboratory studies show that common oxidative dyes lack ovicidal activity and may cause scalp irritation, reducing compliance with recommended regimens. Consequently, professional bodies advise against substituting dye for approved pediculicides.

Adhering to established guidelines maximizes eradication rates and minimizes adverse effects. Hair‑coloring agents should be considered cosmetic only and not a therapeutic measure for lice infestations.

Preventive Measures and Best Practices

Hair dye does not reliably eliminate head‑lice; its chemical composition targets pigment, not the insects’ biology. Effective prevention relies on behavioral controls and proper grooming habits.

Conduct weekly visual inspections of scalp and hair, focusing on the nape, behind ears, and hairline.
Prohibit sharing of combs, brushes, hats, pillows, and hair accessories among children or household members.
Maintain hair cleanliness; wash regularly with mild shampoo, but avoid excessive use of harsh chemicals that may irritate the scalp.
Keep hair tied back or covered in environments where infestation risk is high, such as crowded schools or camps.
Educate children about avoiding head‑to‑head contact during play and sports.

When an infestation occurs, follow these best practices:

Apply a pediculicide approved by health authorities, adhering strictly to dosage and exposure time.
After treatment, use a fine‑toothed nit comb on damp hair to remove dead lice and eggs; repeat combing every 2–3 days for two weeks.
Launder clothing, bedding, and personal items in hot water (≥60 °C) and dry on high heat; items that cannot be washed should be sealed in plastic bags for at least 48 hours.
Inform close contacts so they can inspect and, if necessary, treat their own hair.

If hair dye is considered for cosmetic reasons during an infestation, limit its use to unaffected sections and do not rely on it as a therapeutic agent. Always follow manufacturer instructions and consult a medical professional before combining dye with any lice‑control product.