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Clinician’s Corner: Prescription Head Lice Treatment

Last week we covered the over-the-counter options for Head Lice Control.  Although safe and effective, resistance is becoming a problem and sometimes the need to bring out the “big guns” to take care of those pesky bugs.

Keep in mind though, a lot of treatment failures are due to inadequate environmental controls and are not so much as resistance as re-infestation. Other causes might be improper use of the products dispensed be it not completely covering the hair or not leaving the product on long enough.

OVIDE® (malathion)

Mechanism:  Widely used as a lawn and garden insecticide.  Has been on, and off the market for the past several years. Has “high” egg-killing activity.  This seems to be the “go to” product when concern of resistance to permethrins.

Malathion was first registered as an insecticide in 1956.  Became prescription product (Ovide®) in 1982.

Warnings/Precautions /Adverse Effects

Unpleasant odor, due to sulfhydryl groups


  1. Avoid any open flames-contains 78% alcohol
  2. Apply to dry hair, especially back of head and behind ears.
  3. Wash hands after application.
  4. Allow hair to air dry (no hairdryers!)
  5. After 8-12 hours wash hair with non-medicated shampoo
  6. Reapply in 7-9 days only if required.

ULESFIA®   (benzyl alcohol lotion)           

Mechanism: does not kill eggs but inhibits lice from closing their respiratory spiracles which allows the product to penetrate lice, causing them to asphyxiate. See  very little resistance to this product. Can be used on age 6 months and older. 

APPLICATION INFORMATION:  As with the other topical agents, two applications of Ulesfia, separated by at least seven days are necessary to eradicate lice. May be a good choice for parents concerned with “pediculicides”

NATROBA®  (spinosad)        

  • One treatment is usually needed with Natroba ® Repeat in 7 days only if live lice are seen again.
  • Mechanism: Spinosad is toxic to the nervous system of lice. After periods of excitation, the lice become paralyzed and die.
  • Use in patients at least 6 months of age.
  • DOSAGE: Apply to dry hair. Leave on 10 minutes. Rinse thoroughly. Combing not required.

STROMECTOL (ivermectin) 3mg tablets (usual dose 200mcg/kg)


Ivermectin causes paralysis in the lice and does not kill the eggs.

  • DOSAGE: used for certain parasitic infections (off-label for scabies or lice) use 400mcg/kg. a 15kg child would take about 2 tablets.
  • Repeat dose in 7 days to eradicate any newly hatched lice.

SKLICE (Ivermectin topical)

  • Can be used in patients 6 months of age and older.
  • Completely coat hair. Leave on 10 minutes, then rinse well. No combing needed

Lindane   old brand name was Kwell®, now only as a generic. Second-line treatment.

Trimethoprim-sulfamethoxazole — We think of Bactrim for infections in the lungs, bladder and skin.  This antibiotic does have lice killing capabilities.  Combination therapy with topical permethrin (Nix) and oral trimethoprim-sulfamethoxazole (Bactrim) may be more effective than treatment with permethrin alone. The mechanism of action of trimethoprim-sulfamethoxazole may involve the death of symbiotic bacteria in the louse gut that produce B vitamins necessary for louse survival. This combo is 92% effective compared with only 72% efficacy with permethrin alone.  By itself Trimeth/sulfa was shown to be 78% effective.  With risks of severe skin rash, and allergic reactions it is best to reserve this combo for resistant cases.

Head Lice Chart

Brand name Generic Name Minimum treatment age Ovicidal? (kills nits?) Major warnings/precautions
Nix crème rinse Permethrin 1% 2 months of age and older Good activity  
RID/ A-200 Pyrethrins/pipronyl butoxide Over 2 years of age NO Retreat in 7-9 days. Avoid if allergic to chrysanthemums or ragweed.
Ovide Malathion 0.5% Over 6 years of age. Contraindicated if under age-2 yrs Partially ovicidal Flammable. No hair dryers
Ulesfia Benzyl alcohol 5% Over 6 months of age NO, it suffocates live lice Retreat in 7 days
Sklice Ivermectin lotion 0.5% Over 6 months of age Prevents newly hatched nymphs from surviving. Single treatment only. No combing needed.
Natroba Spinosad 0.9% Over 6 months of age Kills live lice and unhatched eggs Nit combing not required
Lindane (Kwell) Lindane Must weigh over 110 lbs About 50% ovicidal Second line. Potent neurotoxin. avoid

Your Thompson Pharmacist is an excellent resource for treatment of headlice whether products come from over the counter or from the prescription department.  We’ll provide you with all the help you need to get your scholar back in the classroom. Go Ahead and ASK…at Thompson Pharmacy it’s all for YOU!