Lice and Wart Matrix

Cryotherapy (dimethyl ether): products?

Wartner Wart Removal Systems, Compound W Freeze Off, Dr. Scholl's Freeze Away.

Cryotherapy (dimethyl ether): how many times and how often?

Apply once. If the wart is still present after 14 days, apply another treatment, up to 3-4 treatments max within 12 weeks (depending on product).

Cryotherapy (nitrous oxide): products and dosing?

Compound W Nitrofreeze. Apply once for 10-40 seconds depending on wart size and location. May retreat in 14 days if the wart persists, up to 3 times total.

Cryotherapy: maximum application time by wart location?

Max 20 seconds for common warts (hands/fingers/arms). Max 40 seconds for plantar warts (feet).

Cryotherapy: plantar wart preparation?

Soak the foot in warm water for 5 minutes, then file the wart down with a pumice stone before treating.

Cryotherapy: drug class and mechanism of action?

Keratolytic/destructive: destroys the wart by freezing tissue. As tissue freezes, microthrombi form, leading to ischemic necrosis and destruction of HPV-infected cells (keratinocytes). A blister may form under the wart and the wart may fall off after about 10 days.

Cryotherapy: irritant/immune mechanism?

Freezing also causes local irritation and inflammation that may clear the wart through a cell-mediated/immune response.

Cryotherapy: warts treated?

Plantar and common warts.

Cryotherapy: pain side effect?

Pain should last a few minutes up to 1 hour and go away on its own; can take ibuprofen if necessary. Pain increases with longer time on the wart (e.g., 40 sec vs 20 sec).

Cryotherapy: blistering and black dots?

Normal side effect; indicates tissue was damaged.

Cryotherapy: scarring/pigmentation, and how to prevent healthy tissue damage?

Scarring and hypo- or hyperpigmentation can occur. Only treat the wart area, apply a ring of Vaseline to protect healthy skin, and follow the time recommendations for the wart type.

Cryotherapy: serious side effects with aggressive treatment?

Tendon damage and/or nerve damage. Only use for the time recommended in the package insert.

Cryotherapy (dimethyl ether): pros?

May be cheaper than a doctor's appointment for liquid nitrogen; quicker and possibly more effective than salicylic acid; less frequent dosing than salicylic acid (1-3 treatments vs daily treatment).

Cryotherapy: age and pregnancy/lactation?

Indicated for children and adults age 4+. Pregnancy and lactation: no studies, but considered safe because there is no drug absorption.

Cryotherapy: cons?

Must follow instructions carefully to avoid damaging other tissue (especially in children and the elderly); may be more expensive than salicylic acid; pain increases with longer application.

Cryotherapy: flammability caution?

Products are flammable; keep away from flames.

Cryotherapy, salicylic acid: caution in which patients?

Patients who may not feel skin damage or who lack peripheral sensitivity: diabetes, peripheral neuropathy secondary to diabetes, peripheral vascular disease, and the immunocompromised.

Nitrous oxide vs dimethyl ether (DMEP) cryotherapy: efficacy?

Nitrous oxide gives a stronger freeze and is likely more effective. One study: with nitrous oxide 29% of warts resolved after one treatment and 71% after 3 treatments, vs 12% after one and 47% after 3 for DMEP.

Nitrous oxide cryotherapy: con vs dimethyl ether?

May be more painful because of the colder temperature.

Salicylic acid for warts: products by dosage form?

40% pads/plasters: Compound W Pads, Curad Mediplast, Dr. Scholl's clear strips/plantar discs/ultra thin disks, Duofilm Patch for Kids, PediFix Wart Stick. 17% gel/liquid: Compound W Fast Acting Gel/Liquid, Dr. Scholl's liquid, DuoFilm liquid.

Salicylic acid for warts: strengths and wart types?

Plantar warts: 40%. Common and plantar warts: 17% or 40%.

Salicylic acid for warts: frequency and duration?

Apply every 24-48 hours depending on the product, for up to 6-12 weeks.

Salicylic acid for warts: drug class and mechanism?

Keratolytic acid that SLOWLY destroys the virus-infected cells. Also an irritant: local irritation clears the wart through an immune response.

Salicylic acid for warts: side effects?

Skin color changes; potential systemic toxicity if overused or used on large surface areas; can kill healthy tissue/cause skin damage and scarring (use a ring of Vaseline to protect healthy skin).

Salicylic acid for warts: pros?

Available as plasters, patches, bandaids, and gels; inexpensive; few side effects if used as directed (not painful); effective (may be more effective on hands than feet).

Salicylic acid for warts: age and pregnancy/breastfeeding?

Kids and adults age 3+. Pregnancy and breastfeeding: compatible as long as applied only to the wart.

Salicylic acid for warts: cons?

Requires adherence and consistent, frequent application; can damage healthy tissue; slow onset (several weeks, and the wart may take several more to fully resolve; 6-12 weeks typical); if the wart is not gone in 12 weeks, treatment is likely ineffective; products are flammable.

Salicylic acid for warts: allergy caution?

Avoid if known allergy to ASA (aspirin).

Duct tape (silver) for warts: how to use it?

Apply to the wart and leave in place for 6 days. Remove the tape on day 6 in the evening. On day 7 (morning), soak the wart in warm water for 5 minutes, remove the top layer of skin with a disposable emery board, and apply a new piece of duct tape. Repeat for up to 2-3 months or until resolved (approx. 4-12 weeks).

Duct tape for warts: mechanism and warts treated?

Local irritation clears the wart by inducing an immune response. Treats common and plantar warts.

Duct tape for warts: side effect?

Skin irritation.

Duct tape for warts: pros?

Inexpensive and easily accessible. Safe for everyone: pregnant, breastfeeding, children, elderly, and diabetics.

Duct tape for warts: cons?

Aesthetics (don't like the look); some people are allergic to adhesives; limited evidence with mixed results (some data indicate it may be more effective than cryotherapy).

Warts: compare cryotherapy, salicylic acid, and duct tape on age and frequency.

Cryotherapy: age 4+, 1-3 treatments (every 14 days, max 12 weeks). Salicylic acid: age 3+, every 24-48 h for 6-12 weeks. Duct tape: all ages, change weekly (6 days on) for up to 2-3 months.

Warts: which options are acceptable in pregnancy/lactation?

All three (cryotherapy: no absorption; salicylic acid: only on the wart; duct tape: safe).

Warts: which options are flammable?

Cryotherapy (dimethyl ether and nitrous oxide) and salicylic acid products.

Pyrethrins + piperonyl butoxide (Rid shampoo): strengths and age?

Pyrethrins 0.17-0.33% with piperonyl butoxide 2-4%. For children >2 years and adults.

Pyrethrins (Rid): patient instructions?

Apply to DRY hair, behind the ears and back of the neck. Leave in 10 minutes, rinse, then comb for lice to remove eggs. Retreat at day 9. Do not apply more than 2X in 24 hours.

Pyrethrins: mechanism of action?

Block nerve impulse transmission to paralyze and kill lice. Only works on LIVE ADULT lice.

Piperonyl butoxide: role?

Inhibits the breakdown of pyrethrin.

Pyrethrins: lice types treated and side effects?

Head and pubic lice. Irritation, erythema, itching, and swelling at the application site.

Pyrethrins: pros?

Many purchasing options (kit, shampoo, etc.); low toxicity when used as directed.

Pyrethrins: pregnancy and breastfeeding?

Breastfeeding: safe. Pregnancy: not contraindicated, but avoid because safer products exist.

Pyrethrins: cons and cautions?

Excessive contact time or scalp occlusion increases skin absorption; resistance is common (superlice). Avoid contact with eyes/mucous membranes. Avoid in patients allergic to pyrethrins, chrysanthemums, or ragweed.

Permethrin 1% (Nix) cream rinse: patient instructions?

Wash hair with shampoo and NO conditioner. Apply cream to hair, behind the ears and back of the neck. Leave in 10 minutes then rinse in the sink. Comb afterwards for lice to remove eggs. Due to resistance, retreat at day 9. Do not apply more than 2X in 24 hours.

Permethrin spray (Rid and Nix 0.25-0.5%): use?

For the home: upholstered furniture, carpet, curtains, mattresses. Vacuum with a HEPA filter first, then spray.

Permethrin: drug class and mechanism?

Synthetic pyrethroid. Blocks nerve impulse transmission to paralyze and kill lice. Only works on live adult lice.

Permethrin: lice types treated?

Head lice (NOT pubic lice).

Permethrin: side effects?

Greasiness on the scalp and hair; transient pruritus, burning, stinging, irritation. SEs occur in about 10% of patients.

Permethrin and chrysanthemum allergy?

Can be used: permethrin is synthetic (not plant-based), so it typically does not cause allergic reactions in patients with plant allergies, although the box still lists it.

Permethrin: pros?

Effects last up to 10 days; cheaper than Rx options; more effective than pyrethrins with one treatment, but similar efficacy when both are repeated twice, 9 days apart.

Permethrin: age?

Children > 2 months and adults.

Permethrin: pregnancy and breastfeeding?

Breastfeeding: safe. Pregnancy: has the most data and is regarded as the drug of choice for head lice in pregnancy by the CDC and AAP (despite what the book says). Dimethicone and the NuvoDSP method are also safe.

Permethrin: cons and cautions?

Conditioners and silicone-based additives (present in most shampoos) impair adherence to the hair shaft, reducing residual effect. Resistance can be high in certain areas. Avoid contact with eyes/mucous membranes.

Ivermectin 0.5% lotion (Sklice, Rid One & Done): approval and age?

FDA approved for OTC and Rx use for age 6 months and older.

Ivermectin lotion: patient instructions?

Apply the contents of 1 tube to dry hair, thoroughly coating the scalp and hair closest to the scalp. Let sit 10 minutes, rinse with water. Do NOT wash hair with shampoo for 24-48 hours.

Ivermectin lotion: mechanism of action?

Binds selectively and with high affinity to glutamate-gated chloride channels in invertebrate nerve and muscle cells, increasing chloride permeability, causing hyperpolarization, paralysis, and death of the parasite.

Ivermectin lotion: what stages does it work on?

Works on adult lice; unclear about nymphs and nits.

Ivermectin lotion: lice treated and side effects?

Head lice. Better tolerated than pyrethrins/permethrin; very low side effect profile (itching 0.9%). Rarely conjunctivitis, ocular hyperemia, eye irritation, dandruff, dry skin, skin burning sensation.

Ivermectin lotion: pros?

Only ONE application required; no nit comb required (though still recommended to remove nits and dead lice); FDA approved; two US RCTs showed effectiveness of 71% and 76% at 14 days after a single application; may work on lice resistant to pyrethrins/permethrin.

Ivermectin lotion: pregnancy and breastfeeding?

Avoid use in pregnancy and breastfeeding as safer products exist and there are not enough data.

Ivermectin lotion: con?

More expensive than pyrethrins/permethrins.

Dimethicone solution (Nix Ultra Solution): patient instructions?

Apply to dry hair, leave on 10 minutes, rinse and shampoo, then use the nit comb. Do not apply conditioner. Most people need 2 doses 7-9 days apart.

Dimethicone: mechanism of action?

Silicone oil that physically occludes the louse respiratory system (clogs spiracles/breathing holes) and prevents excretion of water. Also lubricates hair to aid removal of nits and lice. Affects adult lice and nymphs; nits must be combed out.

Dimethicone: side effects?

Greasy feeling on hair; can be slippery (clean up immediately; inactive mineral oil). Rarely scalp erythema, irritation, flaking.

Dimethicone: pros?

Potentially more effective than Rid and Nix due to lice resistance to those and its PHYSICAL (non-neurotoxic) mechanism; less irritation; easier combing due to lubricated hair; may need 2 bottles but may work better on thick/curly/coarse hair.

Dimethicone: age and pregnancy/breastfeeding?

Labeled for children >2 years and adults. Pregnancy and breastfeeding: safe (not absorbed).

Dimethicone: cons?

Not FDA approved. RCT cure rates about 70-95% with 2 applications 1 week apart; kills live lice better than eggs.

Nuvo Method/DSP (dry-on, suffocation-based pediculicide) with Cetaphil cleansing lotion: patient instructions?

Apply to dry hair, dry the lotion with a hair dryer, leave on overnight or at least 8 hours, wash out the next morning. Repeat once weekly for 3-4 total treatments.

Nuvo Method/DSP: mechanism of action?

Cetaphil covers breathing holes to suffocate lice; once heated it acts like a shrink-wrap film to continue suffocation. Works on live adult lice and nymphs with a breathing hole.

Nuvo Method/DSP: efficacy and side effects?

An uncontrolled, nonrandomized study reported a 96% cure rate. Scalp irritation. Treats head lice.

Nuvo Method/DSP: pros and cons?

PROS: one study found it more effective than permethrins/pyrethrins; safe in pregnancy/breastfeeding (not absorbed); no age limit. CONS: not FDA approved; requires multiple applications.

Air Alle electronic nit comb: what is it?

Applies heat to dehydrate and kill lice and nits (90% effective against nits). Requires a 30-minute hot air application; expensive and requires a certified/trained technician; cannot use a regular hair dryer; limited efficacy data.

LiceMeister comb: what is it?

FDA-approved nit comb. Treats head lice and nits. Manufactured by the National Pediculosis Association; reusable, will not rust, can be boiled; more effective than plastic combs.

Lice: tea tree oil and lavender?

NOT recommended by the AAP due to toxicity (allergic reactions and possibly liver toxicity).

Lice: occlusive oil-based products (olive oil, mayonnaise, white petrolatum, tub margarine)?

NOT recommended: not very effective; only slow adult lice movement to make combing easier. No published data support them. Also no published data for Rid Super Max Advanced Shampoo, Rid SuperMax, or Rid SuperMax Sensitive Skin (occlusive agents such as hydrogenated didecene/polydecene).

Lice products that act on LIVE ADULT lice only (neurotoxic)?

Pyrethrins and permethrin (only live adult lice). Ivermectin works on adults (nymphs and nits unclear). Physical agents (dimethicone, Nuvo/DSP) work on adults and nymphs with spiracles; nits must be combed out.

Lice products for pregnancy/lactation?

Permethrin (CDC/AAP drug of choice for head lice in pregnancy), dimethicone (Nix Ultra), and Nuvo/DSP are safe. Pyrethrins: avoid in pregnancy (breastfeeding safe). Ivermectin: avoid in pregnancy and breastfeeding.

Lice products: which options address resistance?

Dimethicone (Nix Ultra), ivermectin, and the Nuvo/DSP method, or treat 2X with the neurotoxic agents (day 9 retreatment).

Lice products: ages ranked?

Nuvo/DSP: no age limit. Permethrin: >2 months. Ivermectin: 6 months+. Pyrethrins and dimethicone: >2 years.

Lice treatments: retreatment timing?

Pyrethrins and permethrin: retreat at day 9. Dimethicone: second dose 7-9 days apart. Nuvo/DSP: weekly for 3-4 treatments. Ivermectin: single application only.