Head Lice

• Detection of live lice is necessary to confirm diagnosis of head lice

• Lice are most commonly found behind the ears and at the back of the neck

• Patient may have an itchy scalp, but this is not diagnostic and detection combing should be performed on all family members and close contacts

• Treatment failure - live lice detected after 2 full courses of treatment

• Secondary infection of the scalp due to scratching (bacterial skin infections may present with clinical features such as weeping, oozing, crusting in tandem with systemic symptoms such as fever and malaise)

• A complete treatment course normally takes 7 days i.e. 2 applications, one week apart

• Prior to treatment, confirm presence of live lice (usually done via detection combing)

• Only treat family members with live lice and strive to do this at the same time (i.e. on the same day)

• Detection combing should also be performed 2-3 days and 9-10 days AFTER a complete course of treatment to confirm all lice have been eradicated. Remember that the presence of louse eggs alone does not necessarily equate to treatment failure

• Detection combing can be 'wet' (wet hair typically with something to make it easier for the comb to pass through the hair, such as hair condition) or 'dry' (dry hair) and involves dividing the hair into sections and methodically combing from the root to the tip. It might be useful to place a white piece of paper under the head to see any debris/lice dropping and to check the comb regularly for trapped lice

• Evidence-based treatment options include physical insecticides such as dimeticone 4% lotion (Hedrin^®), and isopropyl myristate and cyclomethicone solution (Full Marks Solution^®); or chemical insecticides such as malathion 0.5% aqueous liquid (Derbac-M^®). Systematic combing of wet hair with a detection/nit comb is a non-chemical alternative. Note the age limits: licensed head lice products are generally for infants aged 6 months and over, and children under 6 months should be treated only under medical supervision (check the individual product literature). See MHRA Drug Safety Update on risk of serious burns with flammable head lice eradication products below

• Dimeticone 4% lotion (Hedrin^®) is widely recommended as a first-line option due to its physical mode of action (which is less prone to resistance than chemical insecticides). Malathion is an alternative, though resistance has been reported in some areas. A second application should be made 7 days after the first (this constitutes one complete course of treatment)

• Hedrin^® lotion must be applied to dry hair (due to its mechanism of action)

• Pregnancy: in addition to wet-combing method, Hedrin^® lotion appears to be safe for use (check product literature at the point of sale)

MHRA Drug Safety Update

Head lice eradication products: risk of serious burns if treated hair is exposed to open flames or other sources of ignition, eg, cigarettes

• some products for the eradication of head lice infestations are combustible/flammable when on the hair and can ignite and cause serious harm in the presence of an open flame or other source of ignition such as when lighting cigarettes
• advise parents, caregivers and the person with head lice, if appropriate, that they should not smoke around treated hair and that it should be kept away from open flames or other sources of ignition, including in the morning after overnight application until hair is washed
• always advise parents and caregivers and the person with head lice to read the instructions that come with treatments to ensure that they are used safely and correctly
• report suspected adverse drug reactions, including burns, to the Yellow Card Scheme