For fast convenient eradication of headlice, use an approved anti-lice medication according to label instructions. 

Because no product kills all eggs (no matter what the label claims!), you should retreat in 7-10 days. This will mop up any newly hatched baby headlice that, as eggs, survived the original treatment.  Don’t forget to eliminate risk of immediate re-infestation by changing pillow cases, pyjamas and towels, and preventing head-to-head contacts with possible headlice carriers. And remember, you must also treat all  infested family members and their friends. 

The wide range of approved pharmaceutical products fall within four major groups, based on their active ingredients. Look for their declaration on the label of all approved products. 

Treatment Categories
1)  Pyrethrins
2)  Synthetic pyrethrins (pyrethroids) like permethrin, bioallethrin, fenothrin.
3)  Organophosphates. Maldison (malathion) is the only one ‘safe’ enough.
4)  Natural products. Most are relatively new formulations containing essential oils and medicinal plant extracts.

Shampoos, lotions or creams 
Lotions, liquids or creams intended to be used neat (undiluted) are best. Shampoos are less effective, because (a) they are diluted too much in use, (b) they have a much shorter time in contact with hair & scalp, and (3) the active ingredient may be inactivated by hot water. If using a shampoo, ensure a minimum amount of water is used before the rinsing stage. Some ‘lotions’ are actually alcoholic solutions. Often, the only hint of alcohol is a warning of flammability. Water-based (aqueous) formulations are preferred for asthmatics, small children and people with eczema. 

Why do some lice treatments fail?
Problems in head lice eradication can occur for several reasons.

1) Not enough product and/or not enough time. Headlice products cannot work unless they come into contact with lice. No contact; No action! (And, if one pregnant female avoids contact, her eggs will develop into the next generation.) All hairs on the head should be covered with sufficient product to treat from roots to tips, particularly for long hair. To ensure proper coverage, comb it in with a normal comb (except for dreadlocks or tightly curled hair). The resulting detangled hair also facilitates fine-tooth combing at the end of the treatment. The product should remain in contact with the hair for about 30 minutes to ensure sufficient exposure.

2) Lice are resistant to the treatment. Head lice have become resistant to some insecticidal ingredients. Some lice are resistant to two ingredients simultaneously. Resistant lice look just the same as sensitive lice, and the best choice treatment will depend on resistance patterns in your area. If lice are moving at 4-8 hours after treatment, use a different insecticide class for a subsequent treatment. Resistance is more likely to occur with products such as malathion, pyrethrins, permethrin (& other synthetic pyrethroids) that leave a very small, non-fatal to lice, residue on the hair after washing. In the USA the CDC says "Treatment failures are common" with pyrethrins and permethrin. Malathion resistance is not a problem in the USA because, being restricted to prescription-only, head lice have not been widely exposed to it.

3) Failure to retreat to kill baby lice newly emerged from eggs. No matter what the product label says, NO product kills 100% of eggs. Eggs take 7-10 days to hatch. Therefore, starting from 1 day after treatment up to 7-10 days, nymphs (baby lice) may be emerging from eggs that survive the first treatment, or were not removed by fine-tooth combing. That's why re-treatment at 7-10 days is vital. If the treatment is effective, you would expect to find nymphs - but no adults - after the first treatment. The second treatment will mop up all remaining nymphs, well before they reach adulthood and reproduce.

4) Re-infection. Re-infection can give an impression that a treatment is not working. Don't forget that head lice can be 'caught' almost immediately after treatment if there is head-to-head contact with someone else who is already infected. (An exception is with oral medication that is not generally available.) Cross infection is likely if an adult louse is detected (with weekly detection combing) within a short time of a head being lice-free. Head lice is a 'communicable disease'. Therefore, to overcome constant re-infections, the challenge is to trace likely contacts, who should be checked for lice and treated if lousy.

5) Formulation and cosmetic elegance ("Yuk factor"). A product which is pleasant and easy-to-use is more likely to be used correctly than one which is not. For example, alcohol based products can cause problems such as stinging and burning, can trigger asthma and worsen eczema. Products with a low "yuk factor" are easier for children to accept on their heads for the full treatment time on both the first and follow-up application. (In the case of Electric Blue products, children approvingly report that it looks and smells like blue bubble gum.)  

Preventing re-infestation
Lice are most commonly spread by head-to-head contact (and indirectly though contaminated clothing or belongings). The best prevention is to trace infested contacts and eliminate headlice from them. Simultaneous treatment of all infested people is necessary to prevent spread-back. Teach your child to avoid activities that are likely to spread lice.

• Avoid head-to-head contact during play at school and at home (slumber parties, sports activities, at camp, on a playground).
• Do not share clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons.
• Do not share infested combs, brushes, or towels.
• Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.

• Dry clean clothing that is not washable, (coats, hats, scarves, etc.)
• Store all clothing, stuffed animals, fluffy comforters, etc., that cannot be washed or dry cleaned into a plastic bag and seal for 10 days at room temperature, or place in a freezer for several hours. 
• Soak combs and brushes for 1 hour in an alcoholic solution, or wash regularly with soap and hot ( above 55 degrees C) water.