#156 The louse is (no longer) in the house
CLINICAL QUESTION
What is the best treatment for head lice?
BOTTOM LINE
Dimeticone (or dimethicone) appears superior to traditional lice treatments (like permethrin or malathion), getting one more in 3-4 patients lice free with no increased adverse events. Dimeticone is a silicone-based product that suffocates lice and is applied to dry hair, left eight hours, and often repeated after one week.
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EVIDENCE
Statistically significant results:
- Dimeticone versus permethrin: Two Randomized Controlled Trials (RCTs):
- British RCT of 90 patients (age 2-45),1 4% dimeticone once or 1% permethrin twice (one week apart), found:
- More dimeticone patients lice free at day nine: 80% versus 36%, Number Needed to Treat (NNT)=3.
- Adverse events similar and none serious.
- Brazilian RCT of 145 children (age 5-15),2 two applications (one week apart) of 92% dimeticone or 1% permethrin found:
- More dimeticone patients lice free at day nine: 97% versus 68%, NNT=4.
- Adverse events: Two cases of ocular irritation from dimeticone.
- British RCT of 90 patients (age 2-45),1 4% dimeticone once or 1% permethrin twice (one week apart), found:
- Dimeticone versus malathion: One British RCT of 73 patients (age 1-48),3 two applications (one week apart) of 4% dimeticone or 0.5% malathion. Analysis (considering drop-outs to have lice) found:
- More dimeticone patients lice free at day nine: 70% versus 33%, NNT=3.
- Other European dimeticone RCTs found cure rates of 83-92%4 and 70% in patients predominantly with longstanding lice and previous failed treatments.5
- 99% of North American lice express genes associated with traditional pediculicide resistance.6
- Dimeticone is a silicone-based product that acts as an occlusive to suffocate lice.7
- Other occlusive agents like isopropyl myristrate also appear more effective than traditional pediculicides.8
- In one study <20% children with nits developed active lice.9
- Wet combing better than visual inspection for diagnosing lice.10
- Head lice primarily transmitted from head to head contact in play, sharing beds, and occasionally by sharing objects like hats, combs.11
- To decrease re-infestation: Wash clothes worn and linens used two days prior in hot water and dry with high heat. Put un-washable items in a sealed bag for two weeks.12,13
- Lice treatments: Cost ~$30 most covered by drug plans.14
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